JP2011090929A - Secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery having a structure in which without additionally installing a piping in order to exhaust a cracked gas generated inside a cell at a faulty time of the cell, the emission of the cracked gas outside a battery case is suppressed. <P>SOLUTION: The secondary battery is equipped with a battery element having a nonaqueous electrolytic solution and the battery case to house the battery element. The battery case is divided into a first space and a second space, the battery element is housed in the first space, and at a border between the first space and the second space, a communication valve is installed to communicate the first space and the second space when a prescribed pressure is applied on the first space. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a secondary battery suitable for use in, for example, an automobile driving power source, and more particularly to a technique for suppressing discharge of an electrolytic solution and decomposition gas from inside a battery cell in an abnormal state.

  In an in-vehicle lithium ion secondary battery, a plurality of single cells (cells) each having a positive electrode, a negative electrode, and an electrolyte are arranged in series to form an assembled battery, and a cell controller for charge / discharge control is connected. Then, the battery module is formed so as to obtain a necessary voltage.

  In lithium-ion cells, for example, if the battery is overcharged without charge control, a gas is rapidly generated inside the battery due to the decomposition of the electrolyte, and the battery case bursts due to the pressure of this gas. there's a possibility that.

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

  However, in a large-capacity battery, since the energy held is large, if the separator of the electrode body is melted due to overcharge of the battery, abnormal heat generation, etc. There was a possibility that combustibles and the like were blown out together with combustible gas. In this case, the combustible gas may be ignited and burned outside the battery case.

  In order to solve this problem, a technique has been disclosed in which two gas discharge ports are provided in a battery case, and two partition plates are provided in two gas passages leading to the two discharge ports (see, for example, Patent Document 1). According to the structure of the battery case, even when the safety valve is operated, it is possible to avoid the high temperature object and the flammable gas from being directly discharged from the inside of the battery to the opening of the safety valve, and the released gas passes through the gas passage once. Is released from the safety valve. Thereby, it is supposed that ignition to a high-temperature object and combustible gas can be prevented.

  Further, in order to solve the above problem, a technique is disclosed in which a metallic tubular member constituting a part of the exhaust gas passage is provided outside each unit battery case, and these unit cells are connected to form an assembled battery. (For example, refer to Patent Document 2). 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. This makes it possible to collect exhaust gas through the exhaust gas passage and discharge it at a low temperature without releasing it to the outside of the periphery of the battery, so that the combustible exhaust gas is ignited. You can prevent problems.

JP 2004-30946 A JP 2002-216731 A

  However, in the technique described in Patent Document 1, there still remains a problem that the electrolyte solution and the combustible gas are discharged into the battery module and short-circuited in the module, or discharged into the atmosphere outside the automobile and ignited. .

  Moreover, in the method of connecting by metal piping described in Patent Document 2, not only the weight of the piping itself increases, but also connecting components and fixing components for ensuring the reliability of the piping are required. 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.

  The present invention has been made to solve the above-described problems of the prior art, and the gas is released to the outside of the battery case without additionally providing a pipe for discharging the electrolytic solution and the combustible decomposition gas. It aims at providing the secondary battery which has a structure which can suppress this.

  The secondary battery of the present invention is a secondary battery comprising a battery element having a non-aqueous electrolyte and a battery case that houses the battery element, and the battery case is divided into a first space and a second space. The battery element is accommodated in the first space, and a communication valve that connects the first space and the second space when a predetermined pressure is applied to the first space at the boundary between the first space and the second space. It is characterized by being provided.

  In the secondary battery having the above-described configuration, the electrolyte of the battery element is decomposed due to overcharge or abnormal heat generation, and the internal pressure of the first space is increased by the decomposition gas. Since the gas can be opened to flow into the second space from the first space, the internal pressure of the first space is reduced correspondingly, and the battery case can be prevented from being ruptured or deformed.

  In the secondary battery of the present invention, the second space is preferably decompressed more than the first space.

  In the secondary battery having the above configuration, since the second space is depressurized, the communication valve is quickly opened as the pressure difference between the first space and the second space becomes significant. Before the pressure becomes extremely high, the internal pressure can be reliably reduced.

  In the secondary battery of the present invention, the second space is preferably provided with a deformation mechanism that is deformed by pressure.

  In the secondary battery having the above configuration, when the internal pressure of the battery case further increases after the communication valve is opened and the gas in the first space flows into the second space, the pressure is provided in the second space by the pressure. Since the deformation mechanism is deformed, by visually confirming the deformation from the outside of the second space, that is, from the outside of the battery case, it can be known that the internal pressure of the battery case has increased, and the internal state of the battery can be determined. Therefore, it is possible to judge whether it is good or bad and easily determine whether or not replacement is necessary.

  In the secondary battery of the present invention, the second space is preferably filled with an adsorbent.

  In the secondary battery having the above configuration, the adsorbent adsorbs the cracked gas when the communication valve is opened and the cracked gas flows into the second space from the first space. More cracked gas can be held in the second space, and the volume of the second space can be reduced by suppressing the increase in the internal pressure of the battery case, so that the cell weight can be reduced and the size can be reduced. It becomes possible.

  The method for manufacturing a secondary battery according to the present invention is a method for manufacturing a secondary battery in which the second space is decompressed more than the first space, and the first space is a portion facing the outside of the battery case. Has a decompression hole, and allows gas to pass through the boundary between the first space and the second space only in one direction from the second space to the first space when the first space is decompressed more than the second space. A check valve for reducing the pressure of the first space from the pressure reducing hole, the pressure of the second space is reduced through the check valve, and the gas is introduced into the first space from the pressure reducing hole.

  In the manufacturing method of the secondary battery, the first space is first decompressed by decompression from the decompression hole, and at the same time, the air in the second space is circulated to the first space by the one-way action of the check valve. The second space can also be depressurized indirectly. Subsequently, when the pressure is increased by flowing gas into the first space from the decompression hole, the pressure in only the first space can be increased while maintaining the decompression in the second space by the backflow preventing action of the check valve. . Thereby, the battery case in which the second space is decompressed more than the first space can be manufactured.

  According to the present invention, there is no need to additionally provide a pipe for discharging the decomposition gas of the electrolytic solution outside the battery case, and the decomposition gas is held in the space provided inside the battery case and released to the outside of the battery case. There is an effect that it can be suppressed. In addition, the deformation mechanism that can be viewed from the outside of the battery allows the internal pressure inside the battery case to be abnormally increased by visual inspection from the outside of the battery, so that the internal state of the battery can be determined. Defects can be determined and it can be easily determined whether replacement is necessary.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows the cell which concerns on one Embodiment of this invention, (a) is a perspective view, (b) is a front view, (c) is a side view, (d) is a bottom view, (e) is a top view FIG. It is a perspective view which shows the cell which concerns on other embodiment of this invention, (a) is a perspective view, (b) is a front view, (c) And (d) is a side view, (e) is a bottom view, (F) is a plan view. It is a perspective view which shows the cell which concerns on other embodiment of this invention, (a) is a perspective view, (b) is a front view, (c) is a side view, (d) is a bottom view, (e) is a bottom view. It is a top view. It is a perspective view which shows the cell which concerns on other embodiment of this invention, (a) is a perspective view, (b) is a front view, (c) is a side view, (d) is a bottom view, (e) is a bottom view. It is a top view.

First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a unit cell according to a first embodiment of the present invention, where (a) is a perspective view, (b) is a front view, (c) is a side view, (d) is a bottom view, (E) is a top view. The unit cell C is a known lithium ion secondary battery or the like, and includes a battery case 10 and a battery lid 11. In the battery case 10, a battery element 24 made of a wound body impregnated with an electrolytic solution, and a positive electrode lead connected to the positive electrode current collector foil 24 a and the negative electrode current collector foil 24 b led to both ends of the battery element 24. A plate 21 and a negative electrode lead plate 23 are accommodated. In each of the positive electrode lead plate 21 and the negative electrode lead plate 23, a positive electrode terminal 20 and a negative electrode terminal 22 are provided outside the battery through the battery lid 11.

  The battery case of the present embodiment includes two spaces, a first space 10 in which the battery element 24 is accommodated, and a second space 30 that is provided between the positive electrode terminal 20 and the negative electrode terminal 22. The space is partitioned by a battery lid 11.

  The battery lid 11 that partitions the first space 10 and the second space 30 has a communication valve that is deformed and destroyed when the internal pressure of the first space 10 exceeds a predetermined pressure and communicates with the second space 30. 32 is formed. When the battery cover 11 is formed, the communication valve 32 is preferentially broken as a weakened part by means such as forming a thinner part than the surrounding part or forming a groove part as a fracture starting point. It is formed to be easy.

  In addition, an explosion-proof valve 31 is provided at the top of the second space 30. The explosion-proof valve 31 is deformed to form a convex portion when the internal pressure of the second space 30 exceeds a predetermined pressure. In the same way as the communication valve 32, the explosion-proof valve 31 has priority over the explosion-proof valve 31 as a weakened part by forming a second space 30 thinner than the surrounding part or by forming a groove. It is formed so as to be easily deformed.

  According to the unit cell of the first embodiment having the above-described configuration, when the electrolyte of the battery element 24 is decomposed due to overcharge or abnormal heat generation, and the internal pressure of the first space 10 is increased by the decomposition gas, the first space 10 The internal pressure of the gas reaches a predetermined pressure, the communication valve 32 is broken and opened, and the cracked gas can flow from the first space 10 into the second space 30. Thereby, the internal pressure of the 1st space 10 reduces correspondingly, and discharge | emission of the gas outside a cell can be suppressed.

  Further, when the decomposition of the electrolytic solution further proceeds and the internal pressure of the first space 10 and the second space 30 rises again, the internal pressure of the second space 30 reaches a predetermined pressure and the explosion-proof valve 31 Deform. As a result, it can be confirmed from the outside of the battery that the internal pressure inside the battery case has risen abnormally, and the internal state of the battery can be judged. It can be easily judged.

  As described above, in the present embodiment, there is an effect that the decomposition gas can be held in the space provided inside the battery case and can be prevented from being released to the outside of the battery case. As described above, since the cracked gas can be processed in the battery case, there is no need to additionally provide a piping and a pipe fixing member for discharging the cracked gas outside the battery case as in the conventional case, and the battery module can be reduced in weight. -Miniaturization is possible. In addition, since the space between the electrodes, which has not been effectively used conventionally, can be used as the second space, it is also effective from the viewpoint of space saving. Further, since the structure is completed in each unit cell, there is no problem of connection reliability between pipes of adjacent unit cells as in the prior art.

  Moreover, in this embodiment, the increase in the internal pressure of the battery due to the decomposition gas can be visually observed from the outside of the battery by the deformation mechanism. In addition, even when the electrolytic solution gradually decomposes due to aging and the internal pressure rises, the battery case itself can be prevented from swelling, so the battery case can be designed to be thin. Can be reduced in weight.

  In this embodiment, even if a malfunction due to abnormal heat generation due to an internal short circuit or overcharge occurs, a combustible substance such as an electrolyte is trapped, so it is discharged out of the cell and reacts with external oxygen to ignite. This can be suppressed.

Second Embodiment FIG. 2 is a perspective view showing a cell according to a second embodiment of the present invention, where (a) is a perspective view, (b) is a front view, and (c) and (d) are side views. (E) is a bottom view and (f) is a plan view. In the following embodiments, the same components as those in the first embodiment are the same as those in the first embodiment, so that the description thereof will be omitted and only the changes will be described.

  In the second embodiment, the second space 30 is accommodated in the battery case 10. A communication valve 32 is formed on the side surface of the second space 30, and an explosion-proof valve 31 is formed on the battery lid 11.

  Even in the single battery according to the second embodiment having the above-described configuration, when the electrolytic solution of the battery element 24 is decomposed by overcharging and the internal pressure of the first space 10 is increased by the decomposition gas, it is provided on the side surface of the second space 30. The cracked gas can flow into the second space 30 from the first space 10 through the communication valve 32 formed. Thereby, the internal pressure of the 1st space 10 reduces correspondingly, and the burst of a battery case can be suppressed. The explosion-proof valve 31 provided in the battery lid 11 is also deformed when the decomposition of the electrolyte further proceeds and the internal pressure of the first space 10 and the second space 30 rises again. As a result, it can be confirmed from the outside of the battery that the internal pressure inside the battery case has risen abnormally, and the internal state of the battery can be judged. It can be easily judged.

  In the present embodiment, the same effect as that of the first embodiment can be obtained, and the second space 30 is completely accommodated in the battery case 10, which is more effective from the viewpoint of space saving. Further, since the second space is arranged inside the battery case, the element can be fixed, and the vibration resistance can be improved at the terminal, the lead, or the lead and the current collector foil welded portion.

Third Embodiment FIG. 3 is a perspective view showing the unit cell according to a third embodiment of the present invention, (a) is a perspective view, (b) is a front view, (c) is a side view, (d) Is a bottom view, and (e) is a plan view. In the third embodiment, the second space 30 is formed in a range where the second space in the first embodiment and the second embodiment exists, and the upper half and the lower half of the second space 30 communicate with each other. It constitutes a space. Similar to the second embodiment, a communication valve 32 is formed on the side surface of the second space 30, and an explosion-proof valve 31 is formed on the top of the second space 30, as in the first embodiment.

  Also in the single battery of the third embodiment having the above configuration, when the electrolyte of the battery element 24 is decomposed due to overcharge or abnormal heat generation, and the internal pressure of the first space 10 is increased by the decomposition gas, the second space 30 The cracked gas can flow into the second space 30 from the first space 10 through the communication valve 32 provided on the side surface. Thereby, the internal pressure of the 1st space 10 reduces correspondingly, and the burst of a battery case can be suppressed. The explosion-proof valve 31 provided in the battery lid 11 is also deformed when the decomposition of the electrolyte further proceeds and the internal pressure of the first space 10 and the second space 30 rises again. As a result, it can be confirmed from the outside of the battery that the internal pressure inside the battery case has risen abnormally, and the internal state of the battery can be judged. It can be easily judged.

  In the present embodiment, the space between the electrode terminals that has not been effectively used conventionally is used as the second space as in the first embodiment. Therefore, the cell module is not only effective from the viewpoint of space saving, but also the first Since the second space extends to the inside of the battery case 10 as in the second embodiment, the region for holding the cracked gas is larger than in both embodiments, and a larger amount of cracked gas can be held. This is effective for a structure for designing a large-capacity cell.

Fourth Embodiment FIG. 4 is a perspective view showing a cell according to a fourth embodiment of the present invention, where (a) is a perspective view, (b) is a front view, (c) is a side view, and (d). Is a bottom view, and (e) is a plan view. In the fourth embodiment, the second space 30 is formed at the bottom of the first space 10. A communication valve 32 is formed at the bottom of the first space 10 (the top of the second space 30), and an explosion-proof valve 31 is formed at the bottom of the second space 30.

  Also in the unit cell of the fourth embodiment having the above-described configuration, when the electrolytic solution of the battery element 24 is decomposed due to overcharge or abnormal heat generation, and the internal pressure of the first space 10 is increased by the decomposition gas, the second space 30 The cracked gas can flow into the second space 30 from the first space 10 through the communication valve 32 provided on the side surface. Thereby, the internal pressure of the 1st space 10 reduces correspondingly, and the burst of a battery case can be suppressed. The explosion-proof valve 31 provided in the battery lid 11 is also deformed when the decomposition of the electrolyte further proceeds and the internal pressure of the first space 10 and the second space 30 rises again. As a result, it can be confirmed from the outside of the battery that the internal pressure inside the battery case has risen abnormally, and the internal state of the battery can be judged. It can be easily judged.

  In the present embodiment, since the second space is formed at the bottom of the first space and the two are integrated to form a rectangular shape on the appearance of the battery, there is no protruding portion and the battery is assembled to the assembled battery. It is effective from the viewpoint of space saving.

Fifth embodiment (example in which the second space is decompressed more than the first space)
In each of the first to fourth embodiments described above, a preferred aspect is that the second space is decompressed more than the first space. According to such an aspect, since the second space is depressurized more than the first space, the communication valve 32 opens quickly as much as the pressure difference between the first space and the second space becomes significant. The internal pressure can be reduced before the internal pressure of the space becomes extremely high. In addition, as compared with the case where the second space is at atmospheric pressure, there is also an effect that a large amount of cracked gas can be held until the deformation mechanism functions because the pressure is reduced from the beginning.

  The manufacturing method of such 5th Embodiment is demonstrated. 1 to 4, a check valve 33 is provided at the boundary between the first space 10 and the second space 30. In addition, the battery lid 11 is provided with an electrolyte inlet 11. The check valve 33 is a check valve that allows gas to flow only in one direction from the second space to the first space and does not flow in the opposite direction. First, the electrolyte injection port 11 is used as a decompression hole, and the first space 10 is decompressed by the decompression from here. At the same time, the air in the second space 30 is circulated to the first space 10 by the one-way action of the check valve 33. By doing so, the second space 30 can also be decompressed indirectly. Subsequently, when gas is flowed into the first space from the inlet 11 to increase the pressure, the pressure in only the first space 10 is increased while the second space 30 is maintained at a reduced pressure by the backflow preventing action of the check valve 33. be able to. Thereby, the battery case in which the second space 30 is decompressed more than the first space 10 can be manufactured.

Sixth embodiment (example in which second space is filled with adsorbent)
In each of the above embodiments, the second space 30 can be filled with an adsorbent of cracked gas. According to such an aspect, when the communication valve 32 is opened and the cracked gas flows into the second space 30 from the first space 10, the adsorbent adsorbs the cracked gas and the electrolyte solution vapor, so there is no adsorbent. More cracked gas can be caused to flow into the second space 30 than in the case, and the second space can be reduced in size by suppressing an increase in the internal pressure of the battery case.

Hereinafter, each component of the present invention will be described in detail.
The positive electrode layer constituting the sheet-like positive electrode layer battery element 24 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 powder is used, and the conductive filler includes acetylene black, ketjen black, VGCF, and the like.

The negative electrode layer constituting the sheet-like negative electrode layer battery element 24 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 occludes and releases lithium ions or an alloy such as Sn, Pb, and Co that forms a metal compound with Li can be used. Examples of the carbon material include natural graphite, artificial graphite, activated carbon, a low-temperature carbon body calcined at 600 to 1200 ° C. (for example, pitch, mesophase pitch as an easily graphitizable carbon precursor, or phenol as a non-graphitizable carbon precursor). Resin, xylene resin, PPS, cellulose, etc.) synthesized by heat treatment in an inert atmosphere.

As the separator layer constituting the sheet-like separator layer battery element 24, a polyolefin microporous separator such as polyethylene, polypropylene or a nonwoven fabric separator such as polyester fiber or aramid fiber can be used.

Examples of the non- aqueous electrolyte non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ- Examples include butyrolactone (γ-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), and 2-methyltetrahydrofuran. 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 ), lithium trifluoromethanesulfonate ( And lithium salts such as LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₃ ) ₂ ]. The electrolyte may be used alone or in combination of two or more. The amount of the electrolyte dissolved in the non-aqueous solvent is usually about 0.2 mol / L to 2 mol / L. Further, 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 storage element manufacturing cylinder, flat winding or stacked type is also possible.

As the electrode terminals of the electrode terminal positive electrode terminal 20 and the negative electrode terminal 22, a metal such as copper, nickel, aluminum, stainless steel, an alloy containing these, or a metal plated with these metals as a base material can be used.

Although battery case aluminum, stainless steel alloy, and resin can be used, aluminum alloy produced by impact molding or transfer press processing is preferable.

Second space (decompression trap)
At the boundary between the second space and the first space, a communication valve for introducing gas from the first space where the battery element is located is mounted. The communication valve is a release valve that is opened at the design pressure, and the method for producing this is to make a slit in the case of the second space, or to make a structure in which a thin aluminum plate is welded to the hole to break it. By making a rubber plug in the hole, the hole can be made to be communicated by being pushed into the second space with the design pressure. The second space is provided with a check valve for reducing the pressure, and is a check valve that can exhaust the gas in the second space only in one direction.

  The second space is preferably filled with an adsorbent that can adsorb electrolyte vapor. When the electrolyte mist enters the second space, it is adsorbed and the volume is reduced, which has the effect of lowering the pressure inside the cell. The adsorbent may be a porous body having a large specific surface area. For example, a material made of an inorganic compound such as zeolite, porous silica, or activated carbon is suitable because it does not burn itself. The shape is particularly preferably 0.5 mm to 2 mm in granular form, pellet form, crushed form, or activated carbon. When the particle size becomes smaller, the gas flows in and out of the cell due to the pressure of gas inflow. On the other hand, if it is too large, the filling property in the case is deteriorated and the filling amount is reduced, so that it is difficult to obtain a sufficient effect of reducing the pressure by the electrolytic solution adsorption.

  The volume of the second space is set in advance by conducting internal short-circuit simulation tests such as overcharge tests and nail penetration tests, and taking data on the amount of vaporization of the electrolyte and the amount of gas generated by the decomposition of the electrolyte. Assume the internal pressure of Next, the size of the second space is designed so that the pressure inside the cell after the communication valve is released does not exceed 0.8 MPa. The explosion-proof valve is set to a higher opening pressure, for example, 1.0 MPa.

The communication valve communication valve breaks at 0.1 to 0.6 MPa and allows gas to flow into the second space when the cell pressure rapidly increases.

Attach a rupture disk to the lid material integrated with the explosion-proof valve terminal, or insert a pressure release slit on the side of the case, and deform it above the design pressure, for example, 1.0 to 1.2 Mpa or more. Prevent rupture.

Depressurization and depressurization are performed by evacuating from the injection port with a rotary pump or the like. When the pressure in the first space is reduced, the check valve is opened by the differential pressure, and the gas in the second space is also exhausted. After decompression, the electrolytic solution can be injected as it is. By installing the check valve, the electrolyte does not enter the decompression section. Further, if the pressure can be reduced, the check valve need not be mounted. For example, a case filled with activated carbon is heated to 80 ° C. or higher, and in this state, YAG welding is performed to seal the second space portion. When the temperature is lowered, the internal pressure is reduced and the pressure reducing unit is completed.

Hereinafter, specific production examples of the present invention will be described.
As the electrode, an electrode body having a positive electrode coating width of 120 mm, a negative electrode coating width of 125 mm, and an uncoated portion of 10 mm was used. A separator having a thickness of 25 μm was used. As the negative electrode current collector foil, a Cu foil was used with a thickness of 14 μm, and as the positive electrode current collector foil, an Al foil was used with a 20 μm foil. LiNi _0.33 Mn _0.33 Co _0.33 O ₂ having a particle diameter D ₅₀ = 12 μm was used as the positive electrode active material, and artificial graphite particles having a particle diameter of 22 μm were used as the negative electrode active material. The thickness of the active material layer after the electrode body press which produced the electrode using PVDF and the binder was 100 micrometers, respectively. The electrode density of the negative electrode was 1.5 g / cm ² , and the electrode density of the positive electrode was 3.85 g / cm ³ .

1) The element manufacturing separator was wound with a biaxial core, and the positive and negative electrodes were inserted between the separators and wound. After completion, the winding core was removed to produce a flat element body having a thickness of 18 mm. An uncoated portion was formed on the left and right sides of the positive electrode and the negative electrode.

2) Welding method Two elements are bundled, a lead tab made of a Cu plate having a width of 45 mm and a thickness of 0.3 mm is applied to the foil formed at both ends, and ultrasonic welding is performed from above. I went in two places. Similarly, the positive electrode was welded with an Al plate having a thickness of 4 mm and a thickness of 0.5 mm. In order to insulate the case and the element, the entire element including the welded portion of the terminal was covered with a polyester resin sheet.

3) Production of lid The lid is a 2 mm plate with positive and negative terminals. The lid has three holes for a liquid injection port, a communication valve, and a check valve. In order to produce a communication valve that operates at 0.4 MPa, a 0.2 mm thick aluminum plate was welded to the hole in the lid portion with YAG to produce a rupture valve. A check valve was inserted into the other hole and welded to the lid with a YAG laser. The check valve operating pressure was 7 kPa.

4) Production of second space An aluminum case having a bottom surface of 38 mm × 90 mm, a depth of 20 mm, and a case thickness of 0.5 mm was produced by impact molding. Activated carbon particles (manufactured by Kuraray Chemical Co., Ltd., GG) were placed inside, and the cell lid part (plate with terminals) was abutted, and the decompression part and lid part were integrated and sealed by YAG welding.

5) The positive and negative lead plates coming out from the lead connecting element were welded and joined to the terminal portion of the case lid.

6) The element prepared in the sealing 5) and the case lid were integrated into a cell case, and the case and lid were welded and sealed with a YAG laser. As the case, a case having a case thickness of 1.0 mm, a thickness of 40 mm, a height of 120 mm, and a width of 160 mm, produced by transfer press using aluminum alloy A3003 was used.

7) The decompression cell in the second space (decompression unit) was placed in a vacuum drying furnace and decompressed with a rotary pump. The inside of the cell is depressurized from the liquid inlet. As a result, the pressure in the decompression unit becomes higher, so the check valve is opened and the gas in the decompression unit is released into the cell. Therefore, both the decompression part and the inside of the cell are decompressed. Furthermore, it vacuum-dried at 60 degreeC for 24 hours. Air having a dew point of −70 ° C. was introduced into the drying furnace and taken out of the furnace. Thereby, the decompression part was completed.

8) The inside of the cell was depressurized in the impregnation glove box, and then impregnation was performed by injecting an electrolyte solution 1.0 M LiPF ₆ / (EC + DMC + EMC). CCCV charging was performed for 24 hours at a current of 0.2 C up to 4.2 V. Thereafter, degassing was performed under reduced pressure, and a rubber stopper was plugged into the injection port to complete the cell.

  According to the present invention, each unit cell constituting the assembled battery suppresses the release of decomposition gas at the time of abnormality to the outside, and is therefore very promising when applied to an in-vehicle lithium ion secondary battery system.

C: Single cell,
10 ... Battery case (first space),
11 ... Battery cover,
12 ... electrolyte inlet,
20: Positive terminal,
21 ... Positive electrode lead plate,
22: negative terminal,
23 ... negative electrode lead plate,
24 ... Battery element,
24a ... positive electrode current collector foil,
24b ... negative electrode current collector foil,
30 ... second space,
31 ... Explosion-proof valve,
32 ... Communication valve,
33 ... Check valve.

Claims (5)

A secondary battery comprising a battery element having a non-aqueous electrolyte and a battery case containing the battery element,
The battery case is partitioned into a first space and a second space,
The battery element is accommodated in the first space,
The boundary between the first space and the second space is provided with a communication valve that connects the first space and the second space when a predetermined pressure is applied to the first space. Secondary battery to do.   The secondary battery according to claim 1, wherein the second space is decompressed more than the first space.   The secondary battery according to claim 1, wherein the second space is provided with a deformation mechanism that is deformed by pressure.   The secondary battery according to claim 1, wherein the second space is filled with an adsorbent. A method for manufacturing a secondary battery according to claim 2,
The first space has a decompression hole in a portion facing the outside of the battery case,
When the first space is depressurized more than the second space, the boundary between the first space and the second space allows gas to pass in only one direction from the second space to the first space. Has a check valve,
Depressurizing the first space from the decompression hole and depressurizing the second space through the check valve;
A method of manufacturing a secondary battery, wherein gas is introduced into the first space from the decompression hole.

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