JP6071336B2 - Non-aqueous electrolyte secondary battery and battery module using the same - Google Patents

Description

  Embodiments described herein relate generally to a non-aqueous electrolyte secondary battery and a secondary battery module using the same.

  In recent years, automobiles using a secondary battery as an energy source have been put into practical use due to the reduction of carbon dioxide emissions and the fear of exhaustion of fossil fuels such as gasoline. The secondary battery is required to have high output, high energy density, small size, light weight, low price, and the like. Furthermore, improvements in safety and durability are indispensable.

As a high energy density secondary battery for automobiles, a lithium ion non-aqueous electrolyte secondary battery is known. This high energy density lithium ion non-aqueous electrolyte secondary battery is known to be obtained by impregnating a non-aqueous electrolyte solution with an electrode assembly in which a positive electrode plate and a negative electrode plate, which are laminated via a separator, are wound, in a can. Yes.
Conventional battery exteriors are generally made by covering and insulating the outer surface of a metal can such as aluminum with a heat-shrinkable tube or PET tape. In this lithium ion secondary battery, measures against overcharging are taken to ensure safety. Since a non-aqueous electrolyte is used, when the battery is overcharged, not only the battery voltage rises, but also the gas pressure rises, and the battery internal temperature rises. In such a state, events such as electrolyte leakage, can deformation, and destruction are also predicted, and measures to prevent the occurrence of these events are required.

  Moreover, in this vehicle-mounted battery, in order to ensure high power energy, a battery module is configured by combining a plurality of batteries. Also in this battery module, a destructive test is performed in order to ensure the safety of the battery. This destructive test is a test for grasping the points of improvement for crushing a battery module and ensuring safety by its behavior. In this test, the battery can generates heat due to a short circuit due to crushing, the non-aqueous solvent gas that is the electrolyte leaks, and the energy stored in the battery may ignite due to a short circuit discharge outside the battery. .

JP 2007-059170 A

  The present embodiment relates to a non-aqueous electrolyte secondary battery or a non-aqueous electrolyte secondary battery capable of suppressing short-circuit sparks and ignition caused by crushing in a battery module combining this battery and a battery module using the same The purpose is to realize.

The non-aqueous electrolyte secondary battery and battery module of the present embodiment contain a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution in a cubic or cuboid hollow bottomed metal can, and the hollow bottomed metal can A non-aqueous electrolyte secondary battery having an opening sealed with a cap member, wherein the ridge line portion of a metal can of the non-aqueous electrolyte secondary battery is covered with a resin coating member, and the non-aqueous electrolyte battery is covered with the resin coating member The ridge line portion of the metal can of the electrolyte secondary battery includes at least a ridge line portion in contact with an end of the cap member of the metal can and a ridge line portion of the bottom surface of the battery can, and the main surface of the battery can and the bottom surface of the battery can Includes a portion not covered with the resin coating member .

  In the present embodiment, the resin-coated member preferably covers the crushing deformation region when the battery body is crushed or deformed by an external pressure or an internal pressure.

FIG. 1 is a perspective view showing an example of a nonaqueous electrolyte secondary battery according to the first embodiment. FIG. 2 is a perspective view showing an example of a non-aqueous electrolyte secondary battery module according to the second embodiment. FIG. 3 is a partially cut perspective view of a battery showing an example of a general non-aqueous electrolyte secondary battery.

  As described above, there is a crush test as a test for ensuring the safety of a battery for use in an automobile. This test is performed by placing the unit cell on a fixed base, pressing it with a long bar-like member parallel to the cap member of the unit cell, and forcibly deforming and breaking the unit cell. That is, when a pressing force exceeding the deformation pressure is applied to the metal can by this pressing, the side surface of the metal can is plastically deformed. At this time, when a pressing force is applied to the electrode assembly, the electrode of the electrode assembly is broken and the temperature in the unit cell rises. Then, the plastic deformation of the metal can extends to the opening and the connection portion with the cap member fixed to the metal can is broken, and the nonaqueous electrolyte leaks. Furthermore, when a short circuit occurs due to the battery energy stored inside the cell, the spark causes the nonaqueous electrolyte solution to evaporate and ignite. It has been confirmed that this spark is generated from the vicinity of the cap member of the unit cell in the initial stage.

  The present embodiment has been completed based on the results of tests for batteries mounted on automobiles. That is, at the stage of deformation and destruction of the unit cell, the leakage of the non-aqueous electrolyte is prevented, and further, the generation and ignition of sparks are prevented, thereby realizing a safe non-aqueous electrolyte secondary battery and battery module. It is.

  The nonaqueous electrolyte secondary battery and the battery module of the present embodiment have at least eight ridges on the cap member surface and the bottom surface of the battery container made of a metal can that has an opening and is a hollow body of a cube or a rectangular parallelepiped. It is characterized by being coated with a resin coating member.

  In the present embodiment, when the battery can of the battery body is crushed and deformed by an external pressure or an internal pressure, the resin coating member preferably covers the crushing deformation region. The resin-coated member is preferably an insulating resin material that is an insulator, and a rubber-like elastic body can be used.

  In the present embodiment, the external pressure or internal pressure applied to the metal can of the battery body is a pressing force applied to the battery can body in a battery destructive test or the like, an accidental drop when using the battery, a pressing force due to a collision, Or the internal pressure which arises by the temperature rise of a battery, etc. is meant.

[First Embodiment: Non-aqueous electrolyte secondary battery]
The nonaqueous electrolyte secondary battery of the present embodiment is composed of a positive electrode, a negative electrode, a separator, an electrolytic solution, and a metal can body that is a container that accommodates these. An example of the structure of this non-aqueous electrolyte secondary battery is shown in FIG. 3, which is a partially cut perspective view.

  As shown in FIG. 3, the metal can body 11 of the non-aqueous electrolyte secondary battery 10 has a hollow bottomed rectangular parallelepiped or hollow bottomed cube shape having an opening, and the opening is sealed in the opening. A cap member 13 to be stopped is arranged. The cap member 13 is provided with terminals 14 and 15 for taking out current, and is connected to an electrode assembly 12 comprising a wound positive electrode, negative electrode and separator inside the battery. In this electrode assembly 12, the positive electrode and the negative electrode are respectively formed by coating a positive electrode active material and a negative electrode active material on the surface of a thin metal foil, and an ion-permeable separator for insulation is provided between these two electrodes. The electrode assembly is constructed by being wound so as to overlap each other and accommodated in the metal can 11, and is accommodated in the metal can 11 together with the electrolytic solution.

  The cap member 13 at the opening of the metal can body 11 may further be provided with a gas discharge valve 16 that is an explosion-proof hole so that the internal gas can be discharged when the battery internal pressure rises. Further, when an excessive current flows inside the battery, a cap member may be provided with a current interrupt mechanism that interrupts the current.

  The metal can 11 has a hollow bottomed rectangular parallelepiped or hollow bottomed cubic shape having an opening, and is obtained by molding a metal such as aluminum. The inside of the metal can 11 is filled with an electrolytic solution made of a non-aqueous compound, and a material that does not chemically react with the electrolytic solution is used, or a coating for insulation is provided inside the metal can. Can also be applied.

  The cap member 13 is formed of an insulating plate material such as polycarbonate, and is hermetically fixed to the opening of the can body 11 by means such as caulking. In the battery of FIG. 3, the cap member 13 has three openings, each provided with a positive terminal 14, a negative terminal 15, and a gas discharge valve 16 that is an explosion-proof hole.

In the lithium ion secondary battery, a non-aqueous electrolyte is mainly used. This non-aqueous electrolyte solution can be used in non-aqueous solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, butyrolactone, diethoxyethane, dioxane, ethyl acetate, lithium borofluoride, lithium perchlorate, lithium hexafluorophosphate, etc. A solute of a lithium salt is dissolved and conventionally known.
The substances shown in the positive electrode, the negative electrode, the separator, or the electrolytic solution are merely examples, and are not limited to these in the present embodiment.

The non-aqueous electrolyte secondary battery (hereinafter referred to as a unit cell) of the present embodiment includes, for example, a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution in a cubic or cuboid hollow bottom metal can as shown in FIG. A non-aqueous electrolyte secondary battery in which the opening of the hollow bottomed metal can is sealed with a cap member, wherein the ridge line portion of the metal can of the non-aqueous electrolyte secondary battery has elasticity. It is a nonaqueous electrolyte secondary battery characterized by being coated with.
An example of this unit cell is shown in FIG.

  As shown in FIG. 1A, the unit cell of the present embodiment includes a cap member 13 disposed so as to seal the opening of the metal can 11, and the cap member 13 includes a positive electrode terminal. 14 and a negative electrode terminal 15 are arranged. And the unit cell of this Embodiment becomes a structure which coat | covers the four ridges which this metal can 11 and the cap member 13 comprise, and the four ridges of the metal can 11 bottom part with the resin coating member 18. FIG. Yes.

  As the resin-coated member of the present embodiment, a film-like member formed of a material having a heat resistance of 100 ° C. or higher, extensibility, rubber-like elasticity, and appropriate breaking strength is suitable. Specifically, materials such as a polytetrafluoroethylene tape and a silicon resin tape can be used. When using such a resin-coated member, a tape-shaped resin-coated member is attached so as to cover the required ridges of the unit cell, and the ends of the tape-shaped resin-coated member are bonded to form the required shape. It is preferable to form.

  Further, it may be a material that is liquid or pasty before coating the battery or the battery module and that solidifies after coating and has the above properties. In this case, a liquid or paste-like resin coating member material is applied to a required portion of the unit cell, and is solidified by a known means such as heat solidification, dry solidification, photosolidification, solidification by ultraviolet irradiation, and the like. A resin-coated member having a shape can also be formed.

  In the present embodiment, the four ridges formed by the cap member of the unit cell and the metal can opening and the four ridges at the bottom of the unit cell are covered with the resin coating member. When a force (internal pressure or external pressure) that crushes the unit cell is applied to the unit cell, the unit cell is destroyed by crushing or deformation first in the ridge line portion where the cap member and the metal can are structurally in contact with each other. . In such a state, when the resin-coated member having flexibility covers the crushing deformation region, leakage of the non-aqueous electrolyte contained in the unit cell is prevented. Furthermore, it is possible to prevent sparks generated by short-circuiting the positive and negative electrodes of the unit cell, and as a result, it is possible to prevent the occurrence of a fire that may be caused by the unit cell collapse.

  In this Embodiment, it is preferable to make the area | region covered with a resin coating member into the ridge part of a metal can, or to include the ridge part of a metal can in the area | region covered with a resin coating member. This is due to the following reason. That is, when charging / discharging using this unit cell, heat is generated by a battery reaction. This heat is released to the outside from the surface of the metal can of the unit cell. When the entire surface of the unit cell is covered with the resin coating member, the heat radiation from the unit cell surface is impaired and the internal temperature rises, and the internal pressure rises accordingly. When a gas discharge port serving as an explosion-proof hole is formed in the cap member of the unit cell, it may be possible to avoid an explosion because the pressure can be leaked from the discharge port. However, in the case of a unit cell in which a gas discharge port is not formed, the sealed portion of the cap member is destroyed, causing non-aqueous electrolyte leakage. Therefore, it is preferable that the coating of the resin coating member is limited to only the ridge line portion of the metal can.

[Modification of First Embodiment]
In the above unit cell, an example of covering the eight ridge lines of the unit cell metal can has been shown, but as shown in FIG. 1B, all the ridge lines of the metal can are covered with a resin coating member. You can also. In this case, it is possible to reduce the possibility of non-aqueous electrolyte leakage and spark generation at the time of battery collapse, and further the occurrence of fire.

[Second Embodiment: Non-aqueous electrolyte secondary battery module]
The non-aqueous electrolyte secondary battery module of the present embodiment can be configured by combining a plurality of the unit cells. An example of this battery module is shown in FIG.
FIG. 2A shows an example in which five unit cells are combined into a module. That is, the unit cells 10 are overlapped so that the directions of the cap members are aligned, and are bound using the resin coating member 18, and the ridge line portion of the battery module is covered.
By making the battery module 20 have this structure, it is possible to effectively prevent the volatilization of the non-aqueous electrolyte vapor generated due to the temperature rise in the cell due to the coil breaking due to the force applied to the battery module 20. .

  In the above-described embodiment, an example in which the unit cells 10 are integrated and then bound by the resin coating member 18 has been shown. However, a predetermined number of resin-coated unit cells shown in FIG. 1A of the first embodiment are integrated. Then, they may be bonded to each other using an adhesive, or may be fixed using an adhesive tape for binding.

[Modification of Second Embodiment]
FIG. 2B shows a modification of the present embodiment. In the battery module 20 of this embodiment, the 12 ridge lines of the unit cell 10 are all covered with the resin coating member 18. This battery module is configured by extending a resin coating member 18 formed in a three-dimensional ladder lattice shape so that the unit cell can be accommodated therein in advance, and disposing the resin coating member 18 by disposing the unit cell 10 therein. I can do it.
In this case, the individual unit cells may be fixed to each other using an adhesive. Alternatively, the unit cell may be further bound using a binding tape. By adopting these means, a material having relatively low mechanical strength such as tensile strength can be used as the resin-coated member material.

  Alternatively, by using a tape-like member formed of a resin-coated member material, the required ridge portion of the battery module is stuck with the tape-like member, and the overlapping portion of the tape-like member is fixed using an adhesive, thereby being required. It is also possible to form a resin-coated member.

  In addition, the battery module of this modification may be configured such that the unit cells shown in FIG. 1B are integrated and bonded together with an adhesive or the like, or may be bound using a binding tape. In this case, a more reliable battery module can be created.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Unit cell 11 ... Battery metal can 12 ... Electrode assembly 13 ... Cap member 14 ... Positive electrode terminal 15 ... Negative electrode terminal 16 ... Explosion-proof hole 18 ... Resin coating member 20 ... Battery module

Claims (8)

A nonaqueous electrolyte secondary battery in which a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte solution are accommodated in a cubic or rectangular parallelepiped hollow bottomed metal can, and an opening of the hollow bottomed metal can is sealed with a cap member. And
The ridge line portion of the metal can of the non-aqueous electrolyte secondary battery is covered with a resin coating member ,
The ridge line portion of the metal can of the non-aqueous electrolyte secondary battery covered with the resin coating member includes at least a ridge line portion in contact with an end of the cap member of the metal can and a ridge line portion of the bottom surface of the battery can,
The nonaqueous electrolyte secondary battery , wherein a main surface of the battery can and a bottom surface of the battery can include a portion not covered with the resin coating member . The non-aqueous electrolyte secondary battery according to claim 1, wherein the resin coating member covers only a ridge line portion of the metal can .   The non-aqueous electrolyte secondary battery according to claim 1, wherein the resin-coated member covers a region where the metal can is crushed by external pressure or internal pressure.   4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the resin-coated member is a polytetrafluoroethylene tape or a silicon resin tape. 5. A non-aqueous electrolyte secondary battery in which a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution are accommodated in a cubic or rectangular parallelepiped hollow bottomed metal can, and an opening of the hollow bottomed metal can is sealed with a cap member, A cube or cuboid non-aqueous electrolyte secondary battery module configured by combining two or more,
Covering the ridge line portion of the battery module with a resin coating member ,
The ridge line portion of the battery module covered with the resin coating member includes at least a ridge line portion in contact with an end of the cap member of the metal can and a ridge line portion on the bottom surface of the battery can,
The nonaqueous electrolyte secondary battery module , wherein a main surface of the battery can and a bottom surface of the battery can include a portion not covered with the resin coating member . The non-aqueous electrolyte secondary battery module according to claim 5, wherein the resin coating member covers only a ridge portion of the battery module.   The non-aqueous electrolyte secondary battery module according to claim 5, wherein the resin coating member covers a region where the metal can is crushed by external pressure or internal pressure.   The non-aqueous electrolyte secondary battery module according to claim 5, wherein the resin-coated member is a polytetrafluoroethylene tape or a silicon resin tape.

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