JP2017054755A - Battery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery device including a method capable of softening the severity of a thermal runaway reaction so as to prevent battery inner pressure from excessively rising due to battery cell expansion or the like and thereby reducing an effect of thermal/mechanical damage.SOLUTION: In a battery device, a battery cell 11 having a flat shape is held in a case 14 while being restricted, a ratchet 17 is provided to plates 15, 16 that restrict one side of the battery cell 11, and, when an internal pressure of the battery cell 11 exceeds a predetermined pressure that is lower than a pressure at which a battery is opened, the ratchet 17 is deformed to be disengaged from the case 14 so that a pressure restricting the battery cell 11 in a lamination direction P is released.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an improvement in a battery device that holds a flat battery in a case in a restrained state.

  For example, a battery device mounted on an electric vehicle or a hybrid vehicle has a structure in which a flat battery is housed and held in a case in a state in which the battery is constrained in the stacking direction along the plate thickness direction (patent) Reference 1).

  In such a battery device, in order to prevent an excessive increase in the internal pressure of the battery due to expansion of the battery cell or the like, a pressure relief valve (cleaving valve) that opens when the internal pressure exceeds a predetermined pressure and reduces the internal pressure is provided. The provided structure is known.

JP 2006-260975 A

  However, as a result of diligent research, we have discovered a phenomenon in which the energy release time is shortened if the battery is pressurized and restrained in the stacking direction when it runs out of heat.

  The object of the present invention is to make the intensity of the thermal runaway reaction mild by increasing the energy release time, and to reduce the influence of thermal mechanical damage.

  Therefore, the present invention provides a battery device in which at least one flat-shaped battery is held in a case in a restrained state, and the battery has a predetermined pressure that is lower than the pressure at which the battery is released. The pressure reducing means for reducing or releasing the pressure for restraining the battery is provided.

  As an example of the pressure reducing means, the case includes a plate that restrains one side of the battery, and the plate is spanned by a frame that forms a peripheral portion of the plate, and the both ends of the plate. A beam locked to a locking portion formed on the inner peripheral edge of the frame, and when the internal pressure of the battery exceeds the predetermined pressure, the beam is released from the locking portion, The pressure for restraining the battery is configured to be reduced or released.

  As another example of the pressure reducing means, the case includes a pair of plates that restrain both sides of the battery, and a fixing bolt that fixes the pair of plates with the battery cell sandwiched between peripheral edges of the pair of plates. And fixing the battery to at least one of the pair of plates and the fixture so as to allow movement of the plate when the internal pressure of the battery exceeds the predetermined pressure. A fragile portion that reduces or releases the pressure for restraining is provided.

  The fragile portion is preferably provided only at the end of the case opposite to the side where the battery terminal is provided. As a result, deformation in the vicinity of the battery terminal on the current attachment side is suppressed, and it is possible to suppress or avoid the occurrence of adverse effects such as a short circuit.

  Alternatively, a detection unit such as a pressure sensor that positively detects or estimates a detection value corresponding to the internal pressure of the battery is provided, and when the detection value exceeds a predetermined pressure, the pressure reduction unit is operated, You may comprise so that the pressure for restraining the said battery may be reduced or released.

  According to the present invention, by increasing the energy release time, the intensity of the thermal runaway reaction can be made mild, and the influence of thermal mechanical damage can be reduced.

The side view which shows the electric vehicle to which a battery apparatus is applied. The top view which shows this electric vehicle. 1 is a cross-sectional view showing a battery device (battery module) according to a first embodiment of the present invention. Cross-sectional view showing a battery device (battery pack) according to a second embodiment of the present invention. The top view which shows the upper side plate of the said 2nd Example. Explanatory drawing which exaggerated and drawn the state at the time of the internal pressure rise of the battery apparatus (battery pack) of the said 2nd Example. Explanatory drawing which exaggerated and depicted the aspect which the beam of the upper side plate of the said 2nd Example remove | deviates from a frame. The cross-sectional view which shows the battery device (battery pack) of the modification 1 of 2nd Example of this invention. Explanatory drawing which exaggerated and drawn the state at the time of the pressure release of the battery apparatus (battery pack) of the modification 1 of the said 2nd Example. The top view which shows the modification of the plate of the battery apparatus (battery pack) which concerns on 2nd Example of this invention or its modification 1,2. The cross-sectional view which shows the battery apparatus (battery module) which concerns on 3rd Example of this invention.

  Hereinafter, embodiments in which the present invention is applied to a battery device for an electric vehicle will be described in detail with reference to the drawings.

  1 and 2 schematically show an electric vehicle 2 to which a battery pack 1 of an embodiment described later is applied. The electric vehicle 2 has a configuration in which a drive motor unit 4 is mounted on a front portion of a vehicle body 3 and drives front wheels 5. The battery pack 1 serving as the energy source of the drive motor unit 4 has, for example, a substantially rectangular box shape as a whole, and is attached to the lower surface of the vehicle body floor 3a from the lower side at a position in front of the rear wheel 6.

  FIG. 3 shows a battery module 10 as a “battery device” according to the first embodiment of the present invention. In the following description, for the sake of convenience, the direction along the stacking direction P (see FIG. 3) is described as the vertical direction, but this does not necessarily mean the vertical direction in the in-vehicle state.

  The battery module 10 is configured as a stack in which a plurality of battery cells 11 as “batteries” according to the first embodiment are stacked and fixed to each other. (See FIGS. 1 and 2). For example, a total of several tens of battery modules 10 are accommodated in the battery pack 1 and connected in series to obtain a voltage of several hundred volts necessary for driving the vehicle.

  The battery module 10 is formed by laminating a plurality of (for example, four) battery cells 11 having a flat shape in a stacking direction P (vertical direction in FIG. 3) along the plate thickness direction, and in the stacking direction P. It is housed and held in the case 14 in a pressurized and restrained state.

The battery cell 11 can use, for example, a general laminated film type lithium ion secondary battery (not shown). For example, it is a flat lithium ion secondary battery in which a power generation element formed by laminating a sheet-like positive electrode plate and a negative electrode plate via a separator is sealed inside an exterior body made of a flexible laminate film together with an electrolyte. A plurality (four in FIG. 3) of the lithium ion secondary batteries are stacked, and positive and negative terminals 12 serving as current extraction portions are led out from one side. Although not shown, the positive / negative terminal 12 is connected in series, parallel, or series-parallel to form a unit.
Further, the battery cell 11 may be provided with a pressure relief valve that peels off the seal portion and releases the internal pressure when the internal pressure rises.

  The case 14 includes a side wall 13, a lower plate 15 and an upper plate 16 that are a pair of plates that restrain and pressurize both the upper and lower sides in the stacking direction P of the plurality of battery cells 11, a claw portion 17, a claw portion and a side wall 13. It is constituted by bolts and nuts for fixing the plate 16 and 17 and is fixed to each other in the laminating direction P by the claw portion 17 at the inclined portion of the periphery of the plates 16 and 17 (expanding toward the outside of the case 14). Yes. The claw portion 17 is a mechanism that is bent when the internal pressure of the battery cell 11 is increased, the upper plate or the lower plate is removed, and thereafter no binding force is applied.

  In this embodiment, when the internal pressure of the battery cell 11 exceeds a predetermined pressure that is at least lower than the pressure applied when the seal is released by the pressure relief valve, the pressure for constraining the battery cell 11 in the stacking direction P is reduced or released. It is comprised as a pressure reduction means. Thus, by increasing the energy release time, the intensity of the thermal runaway reaction can be made mild, and the influence of thermal mechanical damage on the host system such as the battery system can be reduced.

Next, a second embodiment will be described with reference to FIGS. In the first embodiment, the battery module 10 (battery device) is configured using the battery cell 11 (battery). However, in the second embodiment, the present invention is applied to the battery pack 110 (battery device) using the battery module 111 (battery). Is applied.
First, the configuration will be described with reference to FIGS. A battery module 111 in which a plurality of battery cells (for example, the battery cell 11 of the first embodiment) are stacked in a direction orthogonal to the positive / negative electrode surfaces and stored in the case 114 is orthogonal to the positive / negative electrode surfaces of the battery cells. A plurality of layers are stacked in the direction to be stored, and stored in the pack case 114. The pack case 114 has a structure in which a lower plate 115 and an upper plate 116 that are a pair of plates that restrain and pressurize both the upper and lower sides in the stacking direction P of the plurality of battery modules 111 are fixed at the periphery. The bolt 117 is a stud bolt fixed to the lower side plate 115, and after the plurality of battery modules 110 and the upper plate 116 are inserted, the nut 118 is tightened and fixed together.

Note that the peripheral edge of the battery module 111 through which the fixing bolt 117 is inserted is slightly thicker than the central portion, and in a normal state, a gap 119 is secured in the central portion of the adjacent battery modules 111.
As shown in FIG. 5, the upper plate 116 of the pack case 114 has a frame 120 that forms the peripheral edge of the upper plate 116, and a bracing shape that spans across the frame 120. And a beam 121. On the lower side of the inner peripheral edge of the frame body 120, a locking portion 122 having a L-shaped cross section is formed, and both ends of the beam 121 are engaged with the locking portion 122 from the lower side. It has a structure that stops.

  The number and shape of the beams 121 are set so that the battery module 111 can be appropriately pressed and restrained in the stacking direction P. For example, as shown in FIG. Are appropriately combined. As shown in FIG. 6, when some battery cells expand for some reason and the battery module 111 (the uppermost battery module 111 in the example of FIG. 6) expands, the beam 121 is bent and deformed accordingly. Then, when the internal pressure of the battery module 111 exceeds a predetermined pressure, the deflected beam 121 is released from the locking portion 122 of the frame body 120 as shown in FIG. Accordingly, by increasing the energy release time, the intensity of the thermal runaway reaction can be made mild, and the influence of thermal mechanical damage on the host system such as the battery system can be reduced.

  In the following embodiments, the same constituent elements as those in the above-described embodiments are denoted by the same reference numerals, and redundant description will be appropriately omitted. FIG. 8 shows a pack case 114A of a battery pack 110A according to a modification of the second embodiment of the present invention. In the pack case 114 </ b> A, the upper plate 116 </ b> A has a simple plate shape like the lower plate 15. In addition, both ends of the fixing bolt 117 are tightened by the nut 118. As the pressure reducing means, the upper plate 116A and the lower plate 115 are deformed or broken to reduce or release the internal pressure when the internal pressure exceeds a predetermined pressure (pressure lower than the pressure applied when the seal is released). A plate-side weakened portion 124 is provided.

  The plate-side weakened portion 124 has a shape cut out in a triangular cross section on the upper side of the upper plate 116A and the lower side of the lower plate 115, and is weaker than other general portions. It is good to set so that it may break at the time of deformation more than 3 times the allowable deformation width of deterioration.

  Further, the plate-side weakened portion 124 is filled with a filler such as a synthetic resin in order to suppress embrittlement due to vibration or the like. However, in the case where there is no possibility of embrittlement due to vibration or the like, a configuration in which the filler is not filled may be employed.

  Similarly, the fixing bolt 117 is provided with a bolt-side weakened portion 125 that breaks and releases the internal pressure when the internal pressure exceeds a predetermined pressure (pressure weaker than the pressure applied when the seal is released) as the pressure reducing means. ing. The bolt-side weakened portion 125 also has a shape in which the outer peripheral surface in the vicinity of the upper plate 116A and the lower plate 115 is cut into a triangular cross-section, and is weaker than other general portions, but is usually deteriorated. It is set so that it can be broken at the time of deformation more than three times the allowable deformation width.

  The bolt-side weakened portion 125 is also filled with a filler such as a synthetic resin in order to suppress embrittlement due to vibration or the like. However, when there is no possibility of embrittlement due to vibration or the like, a configuration in which the filler is not filled may be employed.

  In addition, the terminal 112 which is an electric current extraction part of each battery module is connected in series, parallel, or in parallel, and is unitized.

  Here, the plate-side fragile portion 124 and the bolt-side fragile portion 125 may be provided only in the vicinity of the right end portion in FIG. 8 that is far from the terminal 112 and the bus bar (not shown). As a result, even when the pack case 114 is deformed, deformation on the side of the current extraction portion is suppressed, so that it is possible to more reliably suppress or avoid the occurrence of adverse effects such as a short circuit.

  If the material of the fixing bolt 117 and the thickness of the nut 118 are appropriately selected instead of the bolt-side weakened portion 125 and the internal pressure exceeds a predetermined pressure (a pressure that is weaker than the pressure applied when the seal is released), FIG. As shown in FIG. 9, the screw thread may be crushed and the nut 118 may be removed to release the fixation. Next, a modification of the plate of the battery device (battery pack) according to the second embodiment or its modifications 1 and 2 will be described with reference to FIG. In this second embodiment, the upper plate 116B and the lower plate 115B are configured as rupture disks as the pressure reducing means of the second embodiment or its modification. The upper plate 116B shown in FIG. 10 will be described as an example. A deformed portion (fragile portion) 126 that is recessed on the lower side (that is, the battery module 111 side) is provided at the center portion of the upper plate 116B. When the pressure exceeds (the pressure that is weaker than the pressure applied when the seal is released), the central deforming portion 126 is deformed so as to be convex upward and the applied pressure can be quickly reduced.

  As a modification of this, if a break line 126A such as a perforation is provided in the central portion of the upper plate 116B and the lower plate 115B and the internal pressure exceeds a predetermined pressure (pressure less than the pressure applied when the seal is released), the break The configuration may be such that the line 126A is broken and the central portion falls off, and the pressure in the stacking direction P on the battery module 111 is quickly reduced / opened. FIG. 11 shows a battery module 10C (battery device) according to a third embodiment of the present invention. The case 14C of the battery module 10C has a box-shaped casing made of an aluminum alloy, and a plurality (six in this embodiment) of battery cells 11C (batteries) are formed in the thickness of the case 14C. Are restrained and held in a stacked state in the stacking direction P. Both ends of the battery cell 11C are held by cell supports 27 and 28 made of synthetic resin. Specifically, the electrode terminal 29 led out from one end of the battery cell 11C is held by one cell support 27, and the other end of the battery cell 11C opposite to the terminal 29 that is a current extraction terminal of the battery cell 11C. In this section, the end 30 of the exterior body made of a laminate film is held by the other cell support 28. A terminal 29 of the battery cell 11C is connected to a bus bar 30, and a terminal 112 </ b> C that is a current extraction portion of the battery module 10 </ b> C led out of the case 14 is connected to the bus bar 30.

  In this embodiment, a sheet-like pressure sensor 32 is attached to the cell support 28 on the side opposite to the terminal 29 as detection means for actively detecting the internal force of the battery cell 11C. In a steady state, an appropriate gap 33 is secured between the cell support 28 opposite to the terminal 29 and the end of the battery cell 11C, so that the pressure sensor 32 is not pressed against the battery cell 11C. However, when the battery cell 11 is pressurized in the stacking direction P due to the expansion of the battery cell 11C, the cell supports 27 and 28 come into contact with the pressure sensor 32, and a detection value corresponding to the internal pressure is detected. The installation position of the pressure sensor 32 may be between adjacent battery cells or between the battery modules of the second embodiment.

  When the detected value exceeds a predetermined threshold value (a value corresponding to a pressure lower than the opening pressure at which the pressure relief valve operates), an appropriate pressure reducing means is operated to move the battery cell 11C in the stacking direction P. The pressure for restraining is configured to be reduced or released. As this pressure reducing means, although not shown, for example, a means for deforming or destroying part of the case 14 using explosives as used in an air bag or the like can be used.

  As an example of the operation level of the sensor indication value of the pressure sensor that operates the pressure reducing means, the battery cell is larger than a state where a sufficient margin is expected from the design maximum value, and the battery cell is opened by the pressure relief valve (cleavage valve). It is set to a range sufficiently lower than the opened state. Accordingly, the restraining pressure on the battery cell is released before the battery cell is opened.

  Thus, by increasing the energy release time, the intensity of the thermal runaway reaction can be made mild, and the influence of thermal mechanical damage on the host system such as the battery system can be reduced.

  In addition to the pressure sensor, any detection means may be used as long as it can detect a detection value related to the internal pressure of the battery module caused by the expansion of the battery cell. A detectable sensor can be used.

  As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, A various deformation | transformation is possible. For example, as the pressure reducing means, the battery case may be formed of an aluminum alloy, and a part of the battery case may be a tightening structure, and when the internal pressure exceeds a predetermined pressure, the structure of the tightening part may be released. Moreover, although the example which applied this invention to the battery module for electric vehicles was demonstrated in the said Example, it can apply similarly to the use other than this, for example, the battery module of a stationary power supply.

In the first and third embodiments, the present invention is applied to a battery module in which a plurality of battery cells are stacked. However, the present invention is similarly applied to a case where a single battery cell is constrained by a case. In addition, the battery pack of the second embodiment or its modification can also be applied to a single battery module.
Further, the restraint method and the pressure reducing means in the first embodiment can be applied to the example of the battery pack in which the battery modules are stacked, and conversely, the second embodiment and its The constraint method and pressure reducing means of the modification can be applied.
Furthermore, the present invention can be similarly applied to a wound battery cell or a battery cell having a ninety-nine-fold electrode structure.

1 ... Battery pack 110, 110A ... Battery pack (battery device)
10 ... Battery module (battery device)
111 ... Battery module (battery)
11, 11C ... battery cell (battery)
12 ... Terminal 14, 14C ... Case 114, 114A ... Pack case 15 ... Lower plate (plate)
16 ... Upper plate (plate)
17 ... Claw 115, 115B ... Lower plate (plate)
116, 116A, 116B ... Upper plate (plate)
117 ... Fixing bolt (fixing tool)
DESCRIPTION OF SYMBOLS 120 ... Frame 121 ... Beam 122 ... Locking part 124 ... Plate side weak part (fragile part)
125 ... bolt side vulnerable part (fragile part)
126 ... Deformation part (fragile part)
32 ... Pressure sensor (detection means)

Claims (7)

In the battery device in which at least one flat battery is held in the case in a restrained state,
A battery device comprising pressure reducing means for reducing or releasing a pressure for restraining the battery when an internal pressure of the battery exceeds a predetermined pressure that is lower than a pressure at which the battery is opened. The case has a plate that restrains one side of the battery,
The plate includes a frame that forms a peripheral portion of the plate, and a beam that spans the frame and has both ends locked to locking portions formed on the inner peripheral edge of the frame. And
The structure is such that when the internal pressure of the battery exceeds the predetermined pressure, the beam is released from the locking portion to reduce or release the pressure for restraining the battery. The battery device according to 1. The case includes a pair of plates that restrain both sides of the battery, and a fixture that fixes the pair of plates across the battery at the peripheral edge of the pair of plates.
At least one of the pair of plates and the fixture is provided with a weak portion that deforms when the internal pressure of the battery exceeds the predetermined pressure and reduces or releases the pressure for restraining the battery. The battery device according to claim 1.   4. The battery device according to claim 3, wherein the fragile portion is provided only at an end of the case opposite to a side where the terminal of the battery is provided. 5. Detecting means for detecting or estimating a detection value corresponding to the internal pressure of the battery;
2. The battery device according to claim 1, wherein when the detected value exceeds the predetermined pressure, the pressure reducing unit is operated to reduce or release the pressure for restraining the battery. The battery is at least one battery cell in which a sheet-like positive electrode plate and a negative electrode plate are laminated via a separator and stored together with an electrolyte in an exterior body made of a laminate film,
The battery device according to claim 1, wherein a direction in which the battery cell is restrained is a direction orthogonal to the electrode surfaces of the positive electrode plate and the negative electrode plate. The battery is a battery module in which a sheet-like positive electrode plate and a negative electrode plate are stacked via a separator, and at least one battery cell stored together with an electrolyte in an outer package made of a laminate film is stored in a case.
The battery device according to claim 1, wherein a direction in which the battery module is constrained is a direction orthogonal to the electrode surfaces of the positive electrode plate and the negative electrode plate.

Images