JP2011090830A - Secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery having a structure capable of keeping the cracked gas of an electrolyte from being released out of a battery case and flowing back into a vehicle interior, without having to additionally provide piping for discharging the cracked gas, and also having an effective cooling structure for a large battery of high energy density. <P>SOLUTION: The secondary battery includes a positive electrode, a negative electrode, a battery element electrically connected between the positive electrode and the negative electrode and having a nonaqueous electrolyte, a battery case for housing the battery element, and a hollow core passing through the battery case and allowing cooling air to circulate through. Space created by the hollow core is independent of space within the battery case. The space created by the hollow core leads to the outside. The hollow core has a safety valve which communicates the space created by the hollow core with the space within the battery case when the space within the battery case reaches a predetermined pressure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lithium ion battery suitable for use in, for example, an automobile driving power source, and in particular, when a decomposition gas of an electrolytic solution is generated inside the battery, the gas is discharged without rupturing the battery. The present invention relates to a technology for suppressing the backflow of gas into a passenger compartment.

  In a lithium ion secondary battery for in-vehicle use, a plurality of single cells (cells) each having a positive electrode, a negative electrode, a separator and an electrolyte solution are arranged in series and housed in a case, and a cell controller for charge / discharge control is connected. Therefore, it is used as an assembled battery that can obtain a necessary voltage.

  In a lithium ion unit cell, for example, when charge control cannot be performed normally and the battery is overcharged, gas is rapidly generated and filled inside the battery due to decomposition of the electrolyte. The case sometimes burst.

  To solve this problem, the battery case is provided with an exhaust valve that releases the internal pressure of the battery, and when the internal pressure rises due to the accumulation of the decomposition gas of the electrolyte, the valve is opened at the design operating pressure. A technique for releasing gas to the outside and preventing the battery case from bursting is generally known.

  However, in such a conventional battery case, there is a possibility that the decomposed gas flows backward through the passage through which the cooling air of the battery flows and reaches the vehicle compartment in which the cooling air is taken.

  Further, in order to solve the problem that the battery case is ruptured by the decomposition gas, a metallic tubular member constituting a part of the exhaust gas passage is provided outside each unit cell case, and these unit cells are connected to form a battery (For example, refer to Patent Document 1). According to this technique, when the unit cells are assembled into the assembled battery, the tubular members of the unit cells are connected to each other, and the exhaust gas passage is configured to distribute the exhaust gas from each unit cell in one. As a result, the exhaust gas can be collected at once through the exhaust gas passage without being discharged outside the battery.

  However, the method of connecting with metal pipes described in the patent literature not only increases the weight of the pipe itself, but also requires connecting parts and fixing parts for ensuring the reliability of the pipe. That is, in order to increase the vibration resistance of the piping, a module restraining structure is required separately, which increases the weight and volume. In addition, from the viewpoint of pipe connection reliability, it is necessary to check the pipe connection and gas leakage of each unit cell, which increases the number of assembly steps and increases the module manufacturing cost. Furthermore, even if the module is dropped or a light collision occurs, the module needs to be replaced to ensure exhaust reliability, resulting in high costs.

  In the technique described in the patent document, the electrode terminal portion protrudes on both sides, and this surface has a waterproof structure. Therefore, the flow path for flowing the cooling air is in a direction to go up and down, but because the cooling air is hindered by the presence of the piping, it causes pressure loss, so it is necessary to increase the fan capacity to blow the cooling air, There are problems such as wind noise.

  By the way, in the case of a square battery, it is preferable to enlarge the battery (thicken) to reduce the metal case ratio from the viewpoint of energy density. However, since the temperature of the battery rises due to heat generated by charging and discharging, Therefore, it is necessary to reduce the thickness direction of the battery and suppress the temperature rise at the center of the element. However, when the thickness is reduced, there is a problem that the metal case ratio is increased because the length is reduced, and the energy density cannot be improved.

  Therefore, when creating large batteries such as those for electric vehicles, it has a reliable structure that can discharge the decomposition gas of the electrolyte outside the passenger compartment, and an effective cooling method for large, high energy density batteries. There was a need for lightweight cells and modules.

JP 2002-216731 A

  The present invention has been made to solve the above-mentioned problems of the prior art, and the decomposition gas is discharged outside the battery case without additionally providing a pipe for discharging the decomposition gas of the flammable electrolyte. It is an object of the present invention to provide a secondary battery having a structure capable of suppressing backflow into the vehicle interior and having an effective cooling structure for a large-sized battery having a high energy density. .

  The secondary battery of the present invention contains a positive electrode, a negative electrode, a separator that does not physically contact the electrode plates between the positive electrode and the negative electrode, a battery element having a non-aqueous electrolyte, and a battery element. Secondary battery having a battery case and a hollow core that passes through the battery case and circulates cooling air, the space formed by the hollow core and the space in the battery case are independent and hollow The space formed by the core communicates with the outside, and the hollow core has a safety valve that communicates the space formed by the hollow core and the space in the battery case when the space in the battery case reaches a predetermined pressure. It is characterized by having.

  In the secondary battery having the above configuration, since the safety valve is provided in the hollow core that penetrates the battery, when the internal pressure of the battery rises due to the decomposition gas of the electrolyte and reaches a certain pressure, the safety valve is It is opened and the decomposition gas is discharged into the space in the hollow core to reduce the internal pressure of the battery and suppress the battery from bursting. Moreover, the cracked gas after discharge | emission can be distribute | circulated as piping as the space in a hollow core. Therefore, when a plurality of the secondary batteries of the present invention are arranged, the spaces in the hollow core are connected and function as one pipe, so that the cracked gas can be recovered on the most downstream side of the pipe. Further, since the hollow core penetrating the battery communicates with the outside, the outside air flows through the space in the hollow core, and the hollow core can function for cooling the battery during normal operation.

  In the secondary battery of the present invention, one end of the hollow core is provided with cooling air introduction means, the cooling air introduction means is provided with a backflow prevention valve, and the backflow prevention valve has a safety valve opened, etc. It is a preferred embodiment that the door is closed in an abnormal state.

  In the secondary battery having the above configuration, since the cooling air introduction means is provided on one side of the hollow core, the cooling air is introduced into the hollow core during normal operation of the battery to efficiently cool the battery. be able to. In addition, since the cooling air introduction means is provided with a backflow prevention valve, when the internal pressure of the battery rises and the decomposition gas is discharged, the upstream air flow into the cooling air is taken in by closing the backflow prevention valve. It is possible to prevent the cracked gas from flowing backward to the passenger compartment.

  In the secondary battery of the present invention, the backflow prevention valve is provided upstream of the fan for circulating the cooling air, and the fan is provided downstream of the safety valve.

  In the secondary battery having the above configuration, when the safety valve is opened and the decomposition gas is released into the hollow core, the upstream backflow prevention valve is closed. At this time, since the fan on the downstream side of the safety valve is continuously driven, the gas density in the downstream side, that is, in the hollow core is lowered from the closed backflow prevention valve. As a result, the decomposed gas remaining in the battery case is drawn out into the hollow core whose atmospheric pressure is lowered from the inside of the battery, and is discharged toward the fan. In this way, the decomposition gas can be discharged more reliably.

  In the secondary battery of the present invention, the hollow core is preferably inclined from the horizontal direction.

  In the secondary battery having the above structure, when the decomposition gas flows into the hollow core and a part of it is condensed and adheres to the hollow core, the hollow core is inclined to condense in a desired direction. The liquid can be discharged. In particular, the backflow into the vehicle interior on the upstream side can be prevented by inclining to the downstream side.

  In the secondary battery of the present invention, the battery element is obtained by winding an electrode group consisting of a sheet-like electrode and a separator around a hollow core, and the safety valve is provided in the non-winding region of the electrode group in the hollow core. It is a preferred embodiment that it is provided.

  In the secondary battery having the above configuration, since the hollow core is also used as the core of the electrode group, the battery capacity can be increased by effectively using the space.

  According to the present invention, there is no need to additionally provide a pipe for discharging the decomposition gas of the electrolyte outside the battery case, and the decomposition gas is discharged into the space inside the hollow core that penetrates the inside of the battery case, thereby Can be prevented. As a result, the assembled battery can be easily assembled, and the weight can be reduced and the size can be reduced while minimizing the capacity reduction. Further, during normal times, cooling air can be used to cool the battery through the space in the hollow core, eliminating the need for a separate exhaust path. As a result, a thick cell with high heat dissipation can be obtained, and both a long life and high energy density can be achieved.

It is a see-through | perspective perspective view of the secondary battery which concerns on one Embodiment of this invention. 1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention. It is a see-through | perspective perspective view which shows the example which arranged the secondary battery which concerns on one Embodiment of this invention. It is a perspective view which shows the example of a change of a battery case and a hollow core. (A) is a perspective view showing an example in which a plurality of secondary batteries of the present invention are arranged, and (b) is a plan view showing an example in which (a) is further provided in a plurality of rows and mounted in an automobile or the like. It is a perspective view which shows the example which arranged the secondary battery of this invention in multiple numbers. It is a schematic diagram which shows the specific example of the cooling air introduction means of this invention. 1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention. 1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention. It is a see-through | perspective perspective view which shows the example which arranged the secondary battery which concerns on one Embodiment of this invention. It is a see-through | perspective perspective view which shows the example which arranged the secondary battery which concerns on one Embodiment of this invention. It is a figure which shows the hollow core of the cell in an Example. It is a figure which shows the battery element of the cell in an Example. It is a figure which shows the battery cover of the cell in an Example. It is a figure which shows the assembly of the cell in an Example. It is a figure which shows the assembly of the cell in an Example. It is a perspective view which shows the cell in an Example. It is sectional drawing of the cell in an Example. It is a perspective view which shows the assembled battery which arranged the several cell in the Example. It is sectional drawing of the assembled battery which arranged the several cell in the Example.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a unit cell according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the unit cell. The unit cell C is a lithium ion secondary battery or the like, and has a cylindrical battery case 10 in which a sheet electrode and a separator are wound around the hollow core 20. A battery element 21 formed or stacked is accommodated. The hollow core 20 is provided with a safety valve 22 that is opened when the internal pressure in the battery case increases and reaches a predetermined pressure. When forming the hollow core 20, the safety valve 22 is preferentially broken as a weakened portion by means such as forming it thinner than the surrounding portion or forming a groove portion as a starting point of breakage. It is formed as follows. Battery lids 11 and 12 are fitted in both openings of the battery case 10, and the space in the battery case 10 is sealed by means such as welding. A positive electrode 30 and a negative electrode 31 that are electrically connected to the battery element 21 are connected to the upper part of the battery case 10. A space penetrating the inside of the cell is formed in the unit cell C by the hollow core through hole 20a, and the space communicates with the outside through the openings 11a and 12a.

  As shown in FIG. 3, a plurality of such unit cells C are assembled into a battery pack, connected to a charge / discharge control device (not shown), and used as a driving power source for an automobile or the like. At this time, the through-holes 20a of the individual cells C are connected to each other as shown in the figure to form one pipe that penetrates the assembled battery.

  According to the secondary battery of the present invention, as shown in FIGS. 1 and 3, during normal operation, the cooling air is circulated through the flow path A passing through the through-hole and the flow path B passing through the outside of the battery. Cooling can be done from inside and outside. Further, when the electrolytic solution is decomposed due to overcharging and decomposed gas is generated and accumulated and the internal pressure in the battery case 11 rises abnormally, the safety valve 22 is opened at a predetermined pressure, and the decomposed gas is transferred to the battery case. 11 is discharged into the through hole 20a of the hollow core 20 from inside. Thereby, the internal pressure of the battery case 11 is reduced correspondingly, and the battery case can be prevented from bursting. The discharged cracked gas is flowed downstream by cooling air along the flow path A with the through-hole 20a as a pipe, and is discharged to the outside or can be collected as necessary.

  As described above, in this embodiment, since the space in the hollow core that penetrates the inside of the battery case is used for cooling during normal times, the heat dissipation efficiency is improved, so that the battery can be formed thick. In addition, since the cracked gas can be discharged when the safety valve is opened, there is no need to additionally provide a piping and piping fixing member for discharging the cracked gas outside the battery case as in the past, and the battery module is lighter and smaller. Is possible.

  FIG. 4 is a diagram showing a modification of the battery case and the hollow core in the secondary battery of the present invention. FIG. 4 (a) has the rectangular case and rectangular hollow core described above, but the secondary battery of the present invention is not limited to this shape. For example, (b) to (d) As illustrated, the shape of the battery case and the hollow core is not limited to a rectangle, a circle, an ellipse, or the like. Moreover, as shown to (e), the aspect which penetrated two or more hollow cores in one battery case, and provided the battery element in each core may be sufficient.

  FIG. 5 is a schematic diagram showing a state in which the unit cell of the secondary battery of the first embodiment is sub-moduleed and packed and installed in an automobile. As shown in FIG. 5B, a plurality of the unit cells C are connected to form a submodule, and the hollow cores of adjacent unit cells are connected to form one pipe. The submodules are further arranged in a plurality of rows and packed. The sub-modules are fixed to the pack case by means such as bolts with a gap for the cooling air flow path B provided. Reference numeral 41 denotes a fixing member that is restrained by the restraining structure 40.

  In the figure, cooling air is taken in from the upstream passenger compartment (not shown) on the left side by cooling air introduction means (vehicle compartment side duct), and is divided into two routes of distribution paths A and B in the cooling air introduction means. Supplied to the battery sub-module. At this time, as shown in FIG. 5A, the distribution path A passes through the hollow core of the secondary battery and cools the secondary battery from the inside, and the distribution path B is, for example, the secondary battery The secondary battery is supplied from above and cools the secondary battery from the outside.

  Even in such a secondary battery submodule or secondary battery pack, when the electrolyte is decomposed due to overcharging of the battery and decomposed gas is generated and accumulated, the internal pressure in the battery case rises abnormally, The safety valve is opened at a predetermined pressure, and the decomposition gas is discharged from the battery case into the through-hole of the hollow core. Thereby, the internal pressure of the battery case is reduced correspondingly, and the battery case can be prevented from bursting. The discharged cracked gas is mixed with cooling air along the flow path A using the through-hole as a pipe, passes through the downstream fan 50, is discharged to the exhaust duct 51, and can be collected as necessary. it can.

  In the present invention, the flow path of the cooling air is not limited to the path passing through the hollow core and the path supplied from above the battery. For example, as one modified example, as shown in FIG. 6, one distribution path A may pass through the hollow core, and the other distribution path B may be supplied from the downstream side of the battery in the direction opposite to the distribution path A. .

  FIG. 7 shows an example of a vehicle compartment side duct which is a cooling air introduction means provided on the upstream side of the secondary battery of the present invention. The vehicle compartment side duct 52 takes cooling air from the vehicle compartment and divides it into two systems of distribution routes A and B and supplies it to the secondary battery. In this example, the backflow prevention valve is provided on the distribution route A side. 53 is preferably provided. This backflow prevention valve 53 detects when an internal pressure abnormally rises in one of the secondary batteries connected downstream, the safety valve is opened, and the decomposition gas of the electrolyte is discharged. It has a function to close the valve.

  According to the backflow prevention valve 53, it is possible to prevent the exhausted cracked gas from flowing back up the pipe into the passenger compartment. As a means for detecting the opening of the safety valve, for example, a strain gauge may be attached to the safety valve, and the check valve 53 may be operated by replacing the opening of the safety valve with an electrical signal. In addition to the strain gauge, a known sensor or the like can be used.

  In such an aspect in which the backflow prevention valve 53 is provided, it is preferable that the backflow prevention valve is further provided upstream of the fan for circulating the cooling air, and the fan is provided downstream of the safety valve.

  According to the above configuration, when the safety valve is opened and the decomposition gas is released into the hollow core, the upstream backflow prevention valve is closed. At this time, since the fan on the downstream side of the safety valve is continuously driven, the gas density in the downstream side, that is, in the hollow core is lowered from the closed backflow prevention valve. As a result, the decomposed gas remaining in the battery case is drawn out into the hollow core whose atmospheric pressure is lowered from the inside of the battery, and is discharged toward the fan. This is because the decomposition gas can be discharged more reliably.

  FIG. 8 shows a modification of the secondary battery of the present invention. As shown in the figure, the battery case 13 is provided with a hollow core that forms a through-hole penetrating the battery as in the past, but the battery element 21 is not directly wound around the hollow core. The battery case 13 is inserted into the space. Thus, the secondary battery of the present invention is not limited to the example in which the battery element is wound around the hollow core, and the battery element manufactured by being wound or laminated independently of the hollow core is placed in the battery case space. A mode of simply inserting is also included.

  9 and 10 show a modification in the embodiment in which the battery element is not wound around the hollow core. As shown in FIG. 9, it is preferable that the battery case 14 has a concave cross section, and one side surface of the hollow core (the bottom of the battery case 14) is open to the outside. According to such an aspect, when a plurality of single cells are arranged as shown in FIG. 10 to form an assembled battery, the sealing member 17 made of a metal or resin or the like separately prepared is fitted into the through hole 15a. Can be formed. As an advantage of this aspect, the battery case 13 shown in FIG. 8 requires a welding process to form the through-hole portion, whereas the battery case 14 having a concave cross section can be easily molded. .

  FIG. 11 shows a modification of the secondary battery of the present invention. As shown in FIG. 11, each hollow core is formed to be inclined, and each battery cover is formed with an opening corresponding to the hollow core through-hole, and is formed when the unit cell is an assembled battery. It is preferable that the one pipe is configured to be a uniformly inclined pipe. According to such an aspect, when the decomposition gas discharged into the hollow core condenses and adheres to the hollow core, the condensate can be discharged in a desired direction. Specifically, since it is not preferable that the condensate flows backward to the passenger compartment side that is upstream, the backward flow to the passenger compartment side can be prevented by inclining the hollow core to the downstream side.

Hereinafter, each component of the present invention will be described in detail.
The sheet-like positive electrode layer constituting the sheet- like positive electrode layer battery element has a structure in which a positive electrode material is bound on both surfaces of a positive electrode current collector made of aluminum. As the positive electrode material of this example, Li oxide is used, and as the conductive filler, acetylene black, ketjen black, VGCF, and the like can be given.

The sheet-like negative electrode layer constituting the sheet- like negative electrode layer battery element has a structure in which a negative electrode material is bound on both surfaces of a negative electrode current collector made of copper or the like. As the negative electrode material of this embodiment, a carbon material that absorbs and releases lithium ions or an alloy that forms a metal compound with Li can be used. Examples of carbon materials include natural graphite, artificial graphite, activated carbon, low-temperature carbon body (organic precursor, for example, graphitizable carbon precursor, pitch, mesophase pitch, non-graphitizable carbon precursor, phenol resin, xylene resin , PPS, cellulose and the like) and carbon synthesized by heat treatment in an inert atmosphere.

Sheet-like separator layer The sheet-like separator layer constituting the battery element may be a polyolefin microporous separator such as polyethylene or polypropylene.

Non-aqueous electrolyte Non-aqueous solvents include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and γ-butyrolactone. (Γ-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents may be used alone or in combination of two or more. Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium boron tetrafluoride (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and lithium trifluoromethanesulfonate. Examples include lithium salts such as (LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₃ ) ₂ ]. The amount of the electrolyte dissolved in the non-aqueous solvent is usually about 0.2 mol / L to 2 mol / L. Various ionic liquids such as LiTFSI may be mixed. In addition, it may be a gel electrolyte retained by the electrolytic solution, and the retaining material may be polyethylene oxide, polypropylene oxide, vinylidene fluoride (VdF), hexafluoropropylene (HFP) or a derivative thereof, or a copolymer. Can do.

A winding metal or resin rigid material such as SUS, aluminum, ABS, or a composite structure in which the center is made of resin and both ends are made of metal can be used.

An electrode plate group is formed by winding a pair of electrode plates that are made of an element-preparing positive electrode plate, a negative electrode plate, and a separator and sandwiching the separator so that the positive electrode and the negative electrode do not physically contact each other. The winding body may be a cylindrical winding or a flat winding, and may be a laminated type.

A rupture disk is attached to the hollow core material of the safety valve or a pressure release slit is inserted, and the cell is prevented from bursting by being deformed and opened at 1.0 to 1.2 Mpa or more.

The battery case can be mainly made of a rigid material such as metal, such as SUS, aluminum, PP (resin), ABS (resin), etc., but an aluminum alloy produced by impact molding or transfer press processing is preferred.

For the electrode terminals of the electrode terminal positive electrode and the negative electrode, metals such as copper, nickel, aluminum and stainless steel or alloys containing these metals can also be used. In order to increase the bonding area between the current collector foil and the terminal portion, a plate shape is preferable.

Electrode terminal connection method The positive and negative current collector foils respectively coming out from both ends of the electrode group are welded to the terminals prepared on the lid portion of the cell using leads or the like, and are electrically connected.

A sealed structure in which the system inside the cell and the outside are completely separated by sealing method welding.

Modularization method The cells are connected so that the hollow portions of each cell are connected and one pipe is formed as a module. An elastic body such as an O-ring that functions as a gasket may be used between the cells.

Cabin side backflow prevention valve A backflow prevention valve is installed in the duct on the side of the car cabin, and when exhaust gas is generated at the time of abnormality, the valve is closed to prevent gas backflow. As a result, the exhaust gas of the battery is exhausted only outside the vehicle compartment, and the influence on the human body due to the backflow into the vehicle compartment is prevented.

Volume efficiency of battery pack In the case of the conventional structure, piping (member) for the exhaust gas path when the battery is abnormal is necessary. Further, the pipe (member) is useless and has no meaning in normal times. However, in the case of the hollow core structure of the present invention, each path can be used as a cooling path in normal times and the hollow path can be used as an exhaust gas path in abnormal times. Will not be needed.

For example, L100mm a general exemplary dimensions of the cells that are used in the examples described below, H100mm, when comparing the unit cells W40mm, the volume of the battery 400000Mm ^3, and the necessary piping attached to the top If the height is 20 mm, an additional space of 80000 mm ³ is added, and the conventional unit cell has a total occupied volume of 480000 mm ³ . When the battery structure of the present invention is used, the upper 20 mm required for the conventional piping can be used for the capacity of the unit cell. However, it is necessary to open the volume of the hollow portion, and when the amount is subtracted, the internal volume of the unit cell of the present invention is 434400 mm ³ , and considering the battery pack that needs to create an exhaust gas structure, the pack volume of the same size The battery capacity can be improved by about 8 to 10%.

  Hereinafter, specific production examples of the present invention will be described.

Cell creation A sheet-like positive electrode layer, a separator layer, a sheet as shown in FIG. 13 around a resin hollow core 60 (hollow size 5 mm × 50 mm × 100 mm, core size 7 mm × 52 mm × 100 mm) shown in FIG. An electrode plate group 61 made of a negative electrode layer was wound. As shown in FIG. 15, the wound body was inserted into a square cylindrical case 74 having two opposite faces opened. (Case dimensions L100 mm × H100 mm × W40 mm). The positive electrode foil 62 and the negative electrode foil 63 of the wound body were bundled, welded to the hollow core 60, and connected to the positive electrode 80 and the negative electrode 81 respectively communicating with the outside of the case 74. A battery lid 75 made of a case material 70, an insulator 71, and an aluminum material 72 shown in FIG. The battery cover 75 has a central portion (a hole 73 (dimension 7 mm × 52 mm) formed in a portion where the hollow core 60 contacts) so as not to block the hollow portion of the hollow core 60. As shown in FIG. The battery case 74 and the battery lid 75 were welded to the hollow core 60 and the battery lid 75, respectively.

In the submodule creation modularization, in this embodiment, since there is no portion for fixing the batteries, a pressing structure from both ends is necessary when modularized. Therefore, the module end cell was fixed and restrained from both sides. In addition, as shown in FIG. 20, the groove part was formed in the location of the battery cover 75 which adjacent cells contact, and the resin O-ring 90 was pinched | interposed as a buffering material. The faces of the battery lids facing each other were pressed together to crush the O-ring to ensure confidentiality.

For the through-hole part (path A) of the both ends of the packed module cell, the through-hole inlet is connected to the cooling air duct (connected to the air conditioner to take in the air-conditioning air in the passenger compartment as cooling air), and the through-hole outlet Was connected to the exhaust duct (to exhaust the exhaust gas outside the passenger compartment). For the outside of the module (path B), the inlet was similarly connected to the cooling air duct, and the outlet was connected to the inside air circulation duct (since it does not become an exhaust gas path, there is no need to exhaust outside the passenger compartment). In both routes, the inlet is a pipe from the same air conditioner, but a backflow prevention valve is provided at the entrance of the duct toward the route A passing through the hollow core. When there is an abnormality (when the cracked gas is discharged from the battery), the check valve is closed to prevent the cracked gas from flowing back into the passenger compartment. It was fixed to the pack case with bolts.

Assuming that the unit cell having the dimensions of L100 mm, H100 mm, W40 mm, and volume 400000 mm ³ produced in the example is a battery having a conventional cracked gas discharge pipe, the height required for the upper pipe is 20 mm. Yes, a space of 80000 mm ³ min is added, and the total occupied volume of the conventional battery is 480000 mm ³ in total. Cell fabricated in Example, the outer shape in 400000Mm ^3, because of which the volume of the battery element portion excluding the volume of the hollow portion was 362000Mm ^3, when this is converted into a conventional battery 480000Mm ^3, and 434400Mm ³ became. Thus, the volume increase of about 8%, that is, the battery capacity could be improved.

  According to the present invention, since the through-hole of the battery is normally used as a flow path for cooling air and is used for discharge of cracked gas at the time of abnormality, the reverse flow of gas to the passenger compartment is suppressed. It is extremely promising when applied to a secondary battery system.

A ... Cooling air flow path (battery inside),
B ... Cooling air flow path (battery outside),
C: Single cell,
10, 13, 14, 74 ... battery case,
11, 12, 15, 16, 75 ... battery lid,
11a, 12a, 15a, 16a ... battery lid opening,
17 ... sealing member,
20, 60 ... hollow core,
20a, 20b, 73 ... through holes,
21, 61 ... battery element,
22 ... Safety valve,
30, 80 ... positive electrode,
31, 81 ... negative electrode,
40: Restraint structure,
41. Fixing member,
50 ... Fan,
51 ... Exhaust side duct,
52. Duct on the passenger compartment side (cooling air introduction means),
53. Check valve,
62 ... positive electrode current collector foil,
63 ... negative electrode current collector foil,
64 ... Safety valve 70 ... Case material,
71. Insulator,
72. Metal material,
90 ... O-ring.

Claims (5)

A positive electrode, a negative electrode, a battery element electrically connected between the positive electrode and the negative electrode and having a non-aqueous electrolyte, a battery case containing the battery element, and a cooling air passing through the battery case A secondary battery having a hollow core to be made,
The space formed by the hollow core and the space in the battery case are independent from each other, and the space formed by the hollow core communicates with the outside.
The hollow core has a safety valve that communicates the space formed by the hollow core and the space in the battery case when the space in the battery case reaches a predetermined pressure. battery. One end of the hollow core is provided with cooling air introduction means,
The cooling air introduction means includes a backflow prevention valve,
The secondary battery according to claim 1, wherein the backflow prevention valve is closed when the safety valve is opened.   The secondary battery according to claim 2, wherein the backflow prevention valve is provided upstream of a fan for circulating the cooling air, and the fan is provided downstream of the safety valve.   The secondary battery according to claim 1, wherein the hollow core is inclined from a horizontal direction. The battery element is obtained by winding an electrode group consisting of a sheet-like electrode and a separator around the hollow core,
The secondary battery according to claim 1, wherein the safety valve is provided in a non-winding region of the electrode group in the hollow core.

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