KR101619422B1 - Electrode Assembly with Improved Safety, and Battery Cell, Battery Pack and Device Comprising the Same - Google Patents

Abstract

The present invention relates to an electrode assembly for preventing a shock applied to a battery from being sheared to an electrode assembly, thereby improving the safety of the battery, and further, by applying a constant pressure to the electrode assembly, The present invention relates to a battery pack comprising one or more unit cell stacks each having two or more unit cells in which an anode and a cathode are positioned with a separating film sandwiched therebetween, An electrode assembly including a jig made of a material, a battery cell including the electrode assembly, a battery pack, and a device.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode assembly having improved battery safety, a battery cell including the electrode assembly, a battery pack and a device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode assembly used in a lithium secondary battery, a battery cell including the electrode assembly, a battery pack and a device, and more particularly, An electrode assembly, a battery cell, a battery pack, and a device having improved safety for preventing the battery pack from being increased.

Generally, in the case of a prismatic or cylindrical battery, as described in Korean Patent Application Publication No. 2007-0025738, an electrode assembly is provided in a rectangular case to form a unit cell, and the outer case is manufactured using a case of a can made of a metal material have. Therefore, when an external impact is applied to the battery, the shock transmitted to the electrode is relatively small, thereby ensuring safety.

However, in the case of a polymer type, that is, a pouch type battery, the outside is made of an aluminum pouch, and external impact tends to be transmitted to the electrode without buffering action by the pouch. As a result, there is a problem that the risk that the impact applied to the battery is transmitted to the electrode and the battery explodes is increased.

On the other hand, in the polymer type battery, the electrode swells due to the swelling of the electrode and the generation of the internal gas during the course of the battery reaction cycle, thereby deteriorating the performance of the battery. Conventionally, in order to solve such a problem, an attempt was made to suppress lifting of the electrode through a structural device outside the cell such as a pack, not inside the cell. However, there is a limitation in suppressing the lifting phenomenon of the electrode through a structural device outside the cell.

In the case of a prismatic or cylindrical battery, the outside is made of a metal can and is relatively strong against an external impact. In the case of a polymer type, that is, a pouch type battery, the outside is made of an aluminum pouch, The present invention also provides a battery cell, a battery pack and a device including the electrode assembly for improving the safety of a battery in a pouch type battery.

In the polymer type secondary battery, the upper and lower portions of the electrode assembly can absorb the impact, and the electrode assembly is protected from external impact by tightening means capable of applying a uniform pressure, thereby completing the strength of the pouch type cell Thereby improving the safety of the battery.

Furthermore, deterioration of the battery performance due to swelling of the electrode due to swelling of the electrode and generation of the internal gas, which may occur during the battery reaction cycle, is suppressed.

[0001] The present invention relates to an electrode assembly, and an electrode assembly of the present invention includes one or more unit cell stacks in which two or more unit cells having an anode and a cathode located therebetween with a separator interposed therebetween, And includes a jig made of a material which is not reactive with the electrolytic solution.

The jig preferably has a thickness of 100 to 1000 mu m, and the jig preferably has an impact strength of 4 to 40 kg / cm / cm.

The jig may be a thermoplastic resin, more preferably a polypropylene (PP), a polyethylene (PE), a polyethylene terephthalate (PET), a polyphenylene sulfide (PPS), a polyether sulfone (PSF), polyphenylene oxide (PPO), polytetrafluoroethylene (PTFE, TFE), polyfluoroethylene (PFE), polyfluoroalkoxy (PFA), ethylene-tetrafluoroethylene copolymer (ETFE) And an epoxy resin.

In the present invention, the jig may include a first flat plate disposed on an upper surface or a lower surface of the unit cell laminate, a second flat plate disposed on the other surface of the unit cell laminate, and a second flat plate disposed between the first flat plate and the second flat plate And a fastening means.

At this time, as an embodiment of the present invention, the jig may be formed integrally with the first flat plate and the fastening means, and the fastening means includes at least two rods extending perpendicularly to the plane of the first flat plate The second flat plate has grooves for receiving the rods corresponding to the rods formed on the first flat plate, and the ends of the rods can be inserted into the grooves formed in the second flat plate and fastened.

According to another embodiment of the present invention, the fastening means is a rod, and the first flat plate and the second flat plate are provided with grooves for inserting the rod into the surfaces corresponding to each other, and the rod is disposed between the first flat plate and the second flat plate So that the jig can be fastened.

According to another embodiment of the present invention, the fastening means is a screw, and the first flat plate has a through hole through which a screw passes but does not penetrate the screw head, and the second flat plate has a through hole A corresponding groove is formed, and the first plate and the second plate are coupled by the screw so that the jig can be fastened.

According to still another embodiment of the present invention, the fastening means is a heat shrinkable band that shrinks at a predetermined temperature, and both end portions of the electrode assembly are surrounded by the heat shrinkable band so that the first and second flat plates are coupled to each other, have.

In the present invention, the unit cell laminate may be a jelly roll type or a laminate of a stack type, a winding type, or a Z folding type.

The present invention provides a battery cell including the electrode assembly.

The battery cell may be a lithium ion secondary battery or a lithium ion polymer secondary battery, and the electrode assembly may be a battery cell embedded in a battery case.

Meanwhile, the battery case may be a pouch type case.

The present invention provides a battery pack including two or more battery cells.

Further, the present invention provides a device including at least one battery cell, wherein the device is a mobile phone, a portable computer, a smart phone, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, In hybrid electric vehicle, or a power storage device.

According to the present invention, a jig made of a material having no reactivity with an electrolytic solution is provided on the outer surface of an electrode assembly in which unit cells are stacked during a battery manufacturing process, so that the battery can be protected against an impact applied from the outside of the battery, Can be improved.

Further, the shape of the electrode assembly can be kept constant by pressing the electrode assembly at a constant pressure by the jig, thereby preventing deterioration of the battery performance due to swelling of the electrode assembly during the battery reaction cycle and electrode fouling caused by gas generation can do.

1 is a schematic view showing an example of a unit cell laminate to which the present invention can be applied.
2 is a view schematically showing a structure in which a jig according to an embodiment of the present invention is fastened to both sides of a unit cell laminate.
FIG. 3 is a view schematically showing an example of release preventing means formed at the end of the rod so as not to easily release the fastening when the flat plate is fastened by a rod in one embodiment of the present invention.
4 is a cross-sectional view schematically showing the concept of fastening a jig by a screw.
5 is a view schematically showing a concept that a jig is fastened by a heat shrinkable band.

Disclosure of the Invention The present invention provides a battery having improved safety by protecting a battery from an impact or the like externally applied to the battery to solve problems such as battery explosion and deterioration in battery performance. It is possible to mitigate or suppress the impact applied to the electrode assembly by providing a jig on the outer surface of the electrode assembly of the electrode assembly.

Hereinafter, the present invention will be described more specifically with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

The electrode assembly of the present invention includes at least one unit cell stack in which two or more unit cells are stacked and a jig installed above and below the surface of the unit cell stack.

The unit cell includes an anode and a cathode, and a separation membrane located between the anode and the cathode. At this time, the unit cells may have different types of electrodes located on both sides, such as an anode / cathode, and may be disposed on both sides of the unit cell such as an anode / a cathode / an anode or a cathode / an anode / The types of electrodes may be the same.

The unit cell stack body is formed by stacking unit cells as described above, and unit cells of the same kind may be stacked, or other types of unit cells may be stacked. At this time, it is preferable that one unit cell and adjacent unit cells are stacked so that different kinds of electrodes face each other with a separation membrane as a boundary.

Although not particularly limited, the unit cell laminate is a laminate formed by laminating a plurality of unit cells including an anode, a cathode, and a separator positioned between the anode and the cathode, wherein FIG. 1 shows a unit cell laminate as an example Respectively. In the present invention, the unit cell laminate may be a stack type as shown in Figs. 1A and 1B. 1 (C), which is formed by folding the sheet-type separation film in a predetermined direction after unit cells are arranged on a single sheet-like separation film at regular intervals, a stack and folding type stack and folding type, winding type, winding type) or Z folding type formed by folding in the zigzag direction. Further, although not shown in the figure, the anode may be a jelly roll type obtained by rolling at least one anode and at least one anode in a cross-laminated manner and separating the anode and cathode with a separator interposed therebetween.

1 (A), the lead tabs of the positive electrode and the negative electrode may be formed at the end of the unit cell laminate on the same side. As shown in FIG. 1 (B) or (C) And lead tabs of different electrodes may be formed at both ends.

The materials of the anode, the cathode and the separator of each unit cell are not particularly limited and can be used without any particular limitation in the present invention as long as they are commonly used in the art.

For example, although not limited thereto, the negative electrode may be made of lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite and the like on both surfaces of a negative electrode current collector produced by copper, nickel, copper alloy, The anode active material coated with the same negative electrode active material may be used. The positive electrode may be formed by coating a positive electrode active material such as lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or the like on both surfaces of a positive electrode current collector made of aluminum, nickel or a combination thereof.

On the other hand, the separation membrane or separation film may be a multilayer film produced by, for example, polyethylene, polypropylene or a combination thereof having a microporous structure, or a multi-layer film prepared by combining polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile or polyvinyl A polymer film for a solid polymer electrolyte or a gel polymer electrolyte such as a fluoride-based polymer, a fluoride-based polymer, and a fluoride-fluoride-hexafluoropropylene copolymer.

The electrode assembly of the present invention has a jig disposed on the outer surface of the unit cell stack body. In the present invention, some examples of unit cell stacks provided with jigs are shown in Figs. 2 to 5. Fig. Hereinafter, the present invention will be described in detail with reference to Figs. 2 to 5. Fig.

The jig 2 is disposed on the outer surface of the unit cell stack 1 and is housed in the battery case by constructing the electrode assembly 10 together with the unit cell stack 2, It is preferable to use a material which does not have a sufficient strength. The material of the jig 2 is not particularly limited as long as it does not react with the electrolytic solution. For example, the jig 2 may be a thermoplastic resin, more preferably a polypropylene (PP), a polyethylene (PE) (PET), polyphenylene sulfide (PPS), polyethersulfone (PES), polysulfone (PSF), polyphenylene oxide (PPO), polytetrafluoroethylene (PTFE, TFE) May be at least one selected from ethylene (PFE), perfluoroalkoxy (PFA), ethylene-tetrafluoroethylene copolymer (ETFE) and epoxy resin.

The jig 2 used in the present invention is not particularly limited. As shown in Fig. 2, the jig 2 includes a first flat plate 3 disposed to face the upper or lower surface of the unit cell laminate 1, And a second flat plate (3) disposed on the other side of the cell laminate (1), wherein the first and second flat plates (3) are bonded to each other via the unit cell laminate (1) (4).

The flat plate 3 of the jig 2 can protect the electrode assembly 10 from external impact applied to the electrode assembly 10 to improve the safety of the battery. Since the flat plate 3 is for protecting the unit cell laminate 1 protected therein from external impacts, the flat plate 3 is preferably capable of completely covering the unit cell laminate 1 Do. Therefore, it is preferable that the flat plate 3 has at least the same size as the surface of the unit cell laminate 1. More preferably, the flat plate (3) of the jig (2) can be thermally contracted due to a temperature rise due to a reaction cycle during operation of the battery, and considering the fastening means (4) 1, but the size is not particularly limited.

The flat plate 3 preferably has a thickness in the range of 100 탆 to 1 mm. If the thickness of the jig flat plate 3 is thinner than the above range, the impact resistance may not be sufficient. On the other hand, if the thickness of the jig 2 is thicker, the impact resistance is expected to be high. However, if the thickness is too large, the overall thickness of the battery may increase.

Furthermore, the jig 2 is required to have a constant strength capable of withstanding an external impact. Therefore, the jig 2 preferably has an impact strength of, for example, 4 to 40 kg · cm / cm.

The fastening means 4 of the jig 2 is not particularly limited as long as it can tighten the two flat plates 3 and apply pressure to the unit cell laminate 1 inserted therein and can be held. For example, as shown in Fig. 2, in the jig 2 of the present invention, the first flat plate 3 and the fastening means 4 may be integrally formed. At this time, the fastening means 4 may be a rod extending perpendicularly to the plane of the first flat plate 3. Meanwhile, the second flat plate 3 may have a groove into which the end of the rod formed in the first flat plate 3 can be inserted. At this time, the groove on the second flat plate 3 may be formed at a position corresponding to the position where the rod on the first flat plate 3 is formed.

The first flat plate 3 and the second flat plate 3 can be bound by inserting the end of the rod integrally formed on the first flat plate 3 into the groove formed in the second flat plate 3, (2) can be fastened. At this time, the rod is fixed to the unit cell stack body 1 in which at least two or more rods are formed on the first flat plate 3 and the unit cell stack body 1 in which the jigs 2 are disposed is fixed, Can be added. For example, a rod may be formed on the first flat plate 3 in a number of three, four, six, eight, and so on.

At this time, it is preferable that the rod is formed at the edge of the first flat plate 3 so that the unit cell laminate 1 can be completely covered by the flat plate 3, Is also formed on the edge of the second flat plate 3 in correspondence with the rod formed on the first flat plate 3.

In this way, the rod formed on the first flat plate 3 is inserted and fixed in the groove formed on the surface of the second flat plate 3, so that the unit cell laminate 1 can be protected from external impact. Further, A constant pressure is applied to the stacked body 1 to suppress the lifting phenomenon of the electrodes during the battery reaction.

At this time, it is preferable that the jig 2 fastened by inserting the end of the rod into the groove formed in the second flat plate 3 is not released easily. To this end, it is preferable to provide the unlocking preventing means 6. The binding release preventing means 6 is not particularly limited as long as the end of the rod can be firmly fixed to the groove. For example, the rod end can be formed as shown in Fig.

That is, the diameter of the rod end portion is formed to be larger than the diameter of the rod body, and the protrusion is formed in the groove, so that the engagement of the rod can be prevented from being released by the protrusion in the groove after fastening. At this time, the groove may be a through hole passing through the flat plate 3, and the end of the rod may be caught by the surface of the flat plate 3 to prevent the unbinding release. At this time, it is preferable to form a step as shown in FIG. 3 so that the end of the rod does not protrude from the outer surface of the flat plate 3.

In another embodiment, the fastening means 4 of the jig 2 may be a pin like rod formed separately from the flat plate 3. [ For example, grooves are formed in both of the two flat plates (3), and two flat plates (3) can be bound by inserting a separate rod into the groove formed in each of the flat plates (3). At this time, the rod and the flat plate 3 can be provided with the binding release preventing means 6 as shown in Fig. 3 as described in the case where the rod is integrally formed on the first flat plate 3, A detailed description thereof will be omitted. On the other hand, the grooves formed on the corresponding surface of the flat plate 3 for insertion of the rod may be through holes.

In another embodiment of the present invention, the rod may be a screw. In this case, as shown in Fig. 4 (a), one of the flat plates 3 is provided with a hole through which the screw passes, and a groove is formed in the other flat plate 3, The two flat plates 3 can be bound. FIG. 4 (b) is a conceptual diagram in which a portion indicated by a circle in FIG. 4 (a) is enlarged and a screw is fastened. Preferably, it is preferable to form a groove on the outer surface of the jig 2 so that the screw head does not protrude from the surface of the jig 2, for example, as shown in Fig. 4 (a).

As another embodiment of the present invention, the fastening means 4 of the jig 2 may be a heat-shrinkable band 7 as shown in Fig. For example, a plurality of heat-shrinkable bands 7 can be wrapped around the edges of the two flat plates 3 and bound. In the case of binding the two flat plates 3 using the heat-shrinkable band 7 in this manner, the band 7 is contracted by heat treatment at a predetermined temperature, so that the two flat plates 3 can be bound.

At this time, the heat shrinkable band 7 is preferably made of a material having no reactivity with the electrolytic solution and having thermal shrinkage characteristics at the battery temperature during the reaction cycle of the battery. In order to improve the wettability of the electrolytic solution during the battery manufacturing process, the heat shrinkage is performed at a high temperature aging process for a long time after the liquid pouring process or the activating process of the electrolytic solution. During the high temperature aging process, heat shrinkage of the heat shrinkable member can be promoted, As a result, the two flat plates 3 can be held together and the jig 2 can be firmly held.

The high-temperature aging process may be performed at a temperature ranging from 50 to 80 ° C. Therefore, for example, it is preferable that the heat shrinkable member is subjected to heat shrinkage at 50 to 80 캜. In the case of shrinking at too low a temperature, it may not be easy to handle during the manufacturing process of the battery due to excessive heat shrinkage. When shrinking at too high a temperature, the heat treatment temperature for shrinking becomes high, have.

The material of the heat shrinkable band 7 is not particularly limited, but may preferably be polypropylene, polyethylene, polyethylene terephthalate, polyester, or a mixture thereof.

The unit cell laminate 1 protected by the jig 2 may be one unit cell laminate 1 and the unit cell laminate 1 may be a plurality of unit cell laminates 1). When the plurality of unit cell stacks 1 are used, the jig 2 may be provided on the outermost surface of the plurality of unit cell stacks 1.

By providing the jig 2 on the outer surface of the unit cell stack body 1 as described above, it is possible to improve the safety of the battery by protecting the battery from the impact applied to the electrode assembly 10, 1) is pressurized at a constant pressure to prevent the swelling of the electrode and deterioration of battery performance due to the generation of gas in the battery when the battery reaction cycle progresses.

The battery cell can be manufactured using the electrode assembly 10 obtained by the present invention as described above. The battery cell can be obtained by embedding the electrode assembly 10 according to the present invention in the battery case and injecting an electrolyte solution. A specific method of manufacturing the battery cell by incorporating the electrode assembly 10 is not particularly limited, and a method commonly used in the art can be suitably applied to the present invention.

At this time, the battery case may be a pouch type case and may have a shape corresponding to the shape of the electrode assembly 10, but is not particularly limited.

Meanwhile, the pouch-type case may be formed of a laminate sheet. The laminate sheet may include an outermost resin layer forming an outermost layer, a barrier metal layer for preventing penetration of a material, and an inner resin layer for sealing, It is not.

The battery case may have a structure in which an electrode lead for electrically connecting the electrical terminals of the unit cells of the electrode assembly 10 is exposed to the outside. An insulating film may be adhered to protect the insulating film.

Meanwhile, the battery cell is not limited thereto, but may be, for example, a lithium ion battery or a lithium ion polymer battery.

The battery cell obtained by the above-described method of the present invention may be used alone or in the form of a battery pack including two or more battery cells. The battery cell and / or the battery pack of the present invention may be used in various devices such as a mobile phone, a portable computer, a smart phone, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, Electric vehicles, electric power storage devices, and the like.

1: unit cell laminate 2: jig
3: (jig) flat plate 4: fastening means
5: screw 6:
7: heat-shrinkable band 10: electrode assembly

Claims (19)

One or more unit cell stacks in which two or more unit cells in which an anode and a cathode are located with a separator interposed therebetween;
A jig provided above and below the surface of the unit cell laminate and made of a material which is not reactive with the electrolyte; And
And a pouch-shaped case made of a laminate sheet for housing the unit cell stack body and the jig,
The jig includes a first flat plate disposed on an upper surface or a lower surface of the unit cell laminate, a second flat plate disposed on the other surface of the unit cell laminate, and fastening means for fastening the first flat plate and the second flat plate to each other ,
The fastening means is a heat shrinkable band that shrinks at a predetermined temperature,
Both ends of the electrode assembly are surrounded by the heat shrinkable band and the first and second flat plates are fastened together,
Wherein the heat shrinkable band causes heat shrinkage at a battery cell temperature during a reaction cycle of the battery cell and causes heat shrinkage during an aging process in which a liquid pouring process or an activating process of the electrolyte solution proceeds later during the manufacturing process of the battery cell.
The battery cell according to claim 1, wherein the jig has an impact strength of 4 to 40 kg · cm / cm.
The battery cell according to claim 1, wherein the jig has a thickness of 100 to 1000 mu m.
The battery cell according to claim 1, wherein the jig is a thermoplastic resin.
The thermoplastic resin composition according to claim 4, wherein the thermoplastic resin is at least one selected from the group consisting of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethersulfone (PES), polysulfone At least one selected from phenylene oxide (PPO), polytetrafluoroethylene (PTFE), polyfluoroethylene (PFE), polyfluoroalkoxy (PFA), ethylene-tetrafluoroethylene copolymer (ETFE) One battery cell.
delete delete delete delete delete The battery cell of claim 1, wherein the electrode assembly is a jelly roll type.
The battery cell according to claim 1, wherein the unit cell stack body is a stack type stacking type, a winding type inding type or a Z folding type stack.
delete The battery cell according to claim 1, wherein the battery cell is a lithium ion secondary battery or a lithium ion polymer secondary battery.
delete delete A battery pack comprising at least two battery cells according to any one of claims 1 to 5 and 11 to 12.
A device comprising at least one battery cell according to any one of claims 1 to 5 and 11 to 12.
19. The device of claim 18, wherein the device is a mobile phone, a portable computer, a smart phone, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or a power storage device.

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