KR20140046434A - Electrode unit with porous structures and second battery using the same - Google Patents

Abstract

The present invention provides an electrode assembly with a porous structure and a second battery including the same, and specifically, to: an electrode assembly including multiple positive electrodes, negative electrodes, and separators; and a secondary battery including the electrode assembly with one or more through-holes, and a penetration sealing unit additionally sealed on a position corresponding to the through holes. The secondary battery according to the present invention: adds and stably fixes a fusion portion of the electrode assembly and a battery case, thereby controlling the movement of the electrode assembly, preventing the internal short circuit, and improving safety; and has the electrode assembly with the porous structure, thereby remarkably improving the penetration properties of electrolyte.

Description

Electrode assembly with a porous structure and a secondary battery comprising the same {Electrode unit with porous structures and second battery using the same}

The present invention relates to an electrode assembly having a porous structure and a secondary battery including the same.

As technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries capable of meeting various demands have been conducted.

Typically, in view of the shape of the battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery that can be applied to products such as mobile phones with a small thickness. In terms of materials, lithium ion batteries having high energy density, discharge voltage, There is a high demand for a lithium secondary battery such as a lithium ion polymer battery.

 FIG. 1 schematically shows a general structure of a typical conventional pouch-type secondary battery as an exploded perspective view.

Referring to FIG. 1, a pouch type secondary battery 100 includes an electrode assembly 300, electrode tabs 310 and 320 extending from the electrode assembly 300, electrodes 310 and 320 welded to the electrode tabs 310 and 320, Leads 410 and 420, and a battery case 200 that accommodates the electrode assembly 300.

The electrode assembly 300 is a power generating element in which an anode and a cathode are sequentially stacked with a separator interposed therebetween, and has a stacked or stacked / folded structure. The electrode tabs 310 and 320 extend from the respective electrode plates of the electrode assembly 300 and the electrode leads 410 and 420 have a plurality of electrode tabs 310 and 320 extending from the respective electrode plates, And a part of the battery case 200 is exposed to the outside. An insulating film 430 is attached to the upper and lower surfaces of the electrode leads 410 and 420 in order to increase the degree of sealing with the battery case 200 and at the same time to ensure an electrically insulated state.

The case 200 is made of an aluminum laminate sheet, provides a space for accommodating the electrode assembly 300, and has a pouch shape as a whole. 1, a plurality of positive electrode tabs 310 and a plurality of negative electrode tabs 320 may be coupled to the electrode leads 410 and 420. In the stacked electrode assembly 300, The upper end is spaced apart from the electrode assembly 300 by a predetermined distance.

Since the electrode assembly 300 and the battery case 200 are fixed to each other by sealing the sealing portions of the battery case together with the electrode leads 410 and 420, (200).

FIG. 2 is a partial enlarged view of an upper part of a battery case in which positive electrode tabs are connected in a dense form in the secondary battery of FIG. 1 and connected to the positive electrode lead.

2, a plurality of positive electrode tabs 310 protruding from a positive electrode current collector 301 of an electrode assembly 300 are formed in the form of a bonded portion integrally joined by welding, for example, (Not shown). Such a cathode lead 410 is sealed by the battery case 200 in a state in which the opposite end portion 412 to which the positive electrode tab weld portion is connected is exposed.

The inner upper end of the battery case 200 is spaced from the upper end surface of the electrode assembly 300 by a certain distance and the positive electrode tabs 310 of the welded portion are connected to each other, Is bent in a substantially V-shape.

Therefore, the bonding portion between the electrode tabs and the electrode lead may be referred to as a V-forming portion. In such a pouch-type secondary battery, the electrode assembly is easily moved along the interface with the battery case due to the vacancy of the V-forming portion when the battery is vibrated or dropped.

Particularly, the lithium salt-containing electrolyte injected into the battery case acts as a kind of lubricant at the interface between the electrode assembly and the battery case, thereby further promoting the movement of the electrode assembly. Such movement of the electrode assembly causes internal short-circuiting due to contact of different electrodes at the V-forming region and ultimately degrades the safety of the battery. Therefore, a method for securing safety in manufacturing the pouch- need.

In this regard, Japanese Patent Application Laid-Open No. 2005-183820 discloses a secondary battery having an electrode assembly composed of a positive electrode / separator / negative electrode embedded in an upper and a lower battery case, which are mutually insulated, An adhesive layer composed of an electrically conductive adhesive agent and an organic solvent contained in the electrolyte is formed between the electrode forming the outer surface and the inner surface of the upper and lower cases and heat treated to fix the electrode assembly stably in the battery case, And the electrode and the upper and lower cases are electrically connected to each other.

However, the above-described technology is complicated in that the manufacturing process of the battery as a whole is complicated and the deterioration of the other members such as the electrode active material and the electrolyte during the heat treatment process of the adhesive layer is suppressed because the adhesive layer is made into paste and applied and exhibits adhesiveness by heat treatment .

Accordingly, there is a high need for a technique capable of fundamentally solving the overall safety by preventing the flow of the electrode assembly inside the battery casing.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art and the technical problems required from the past.

An object of the present invention is to provide a secondary battery capable of preventing an internal short circuit by suppressing movement of an electrode assembly by stably fixing a battery case and an electrode assembly, and ultimately ensuring excellent safety.

Another object of the present invention is to provide a secondary battery including an electrode assembly having improved impregnation properties for an electrolyte solution.

The present invention has been made to solve the above problems, in the electrode assembly comprising a plurality of anodes, cathodes and separators, provides an electrode assembly comprising one or more through holes.

In one embodiment, the at least one through-hole may be two.

Further, the at least one through-hole may be formed in any shape selected from the group consisting of a circle, an ellipse, a curvature square, a square, and a triangle formed such that its apexes have a curvature, and the at least one through- .

According to another embodiment, the at least one through-hole may be formed in the same shape.

Meanwhile, the at least one through-hole may be formed at equal intervals.

Further, the at least one through-hole may be formed along the central portion in the long side direction of the electrode assembly, or the at least one through-hole may be formed along the central portion in the short side direction of the electrode assembly .

Meanwhile, the total area occupied by the at least one through-hole may be 2% to 20% of the area of the electrode assembly.

In addition, the electrode assembly may be one selected from the group consisting of a jelly-roll type, a stack type, a stack / folding type, and a Z-stack / folding type.

The present invention, on the other hand, relates to the electrode assembly of the present invention described above; And a pouch-type battery outer casing and a through-hole sealing portion.

At this time, the pouch-type battery outer casing may have a structure of an inner resin layer, a metal thin film, and an outer resin layer. Further, the through-hole sealing portion may include a corresponding portion of the pouch- It may be formed by sealing.

The present invention further provides a secondary battery module or a battery pack including one or more pouch type secondary batteries.

At this time, the secondary battery module or the battery pack is used as a power source of the middle- or large-sized device, and the middle- or large-sized device includes a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric motorcycle including E-bike, E-scooter; Electric Golf Cart; Electric truck; Electric commercial vehicle; Or it may be a secondary battery module or a battery pack, characterized in that any one of the system for power storage.

The present invention also relates to an electrode assembly comprising an anode, a cathode and at least one through-hole at the same position on the separator; And a pouch-type battery outer casing made of a structure of an inner resin layer, a metal thin film, and an outer resin layer, and further sealing the pouch-type battery outer casing at a position corresponding to the through-hole formed on the electrode assembly, The present invention further provides a method of manufacturing a battery.

In this case, the through-hole sealing part may be manufactured using a thermal welding apparatus having a pressing part corresponding to the position and shape of the through-hole so as to press the corresponding part.

As described above, the secondary battery according to the present invention can be stably added to the electrode assembly and the fusion part of the battery case to stably fix the movement of the electrode assembly, thereby preventing internal short circuiting and increasing safety, and increasing porosity. Due to the structure of the electrode assembly of the structure there is an effect that can greatly increase the impregnation of the electrolyte.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

1 is an exploded perspective view of a conventional structure of a conventional pouch type secondary battery.
FIG. 2 is a partial enlarged view of an upper part of a battery case in which positive electrode tabs are connected in a densely packed manner to the positive electrode lead in the secondary battery of FIG. 1;
3 is an exploded perspective view of a secondary battery according to an embodiment of the present invention.
FIG. 4 is a perspective view of the secondary battery according to FIG. 3 in a coupled state.
FIG. 5 is a perspective view of a secondary battery according to another embodiment of the present invention in a coupled state.

In order to solve the above-described problems,

An electrode assembly comprising a plurality of positive electrodes, a negative electrode and a separator, the electrode assembly including at least one through-hole for sealing, and a secondary battery comprising the same.

The secondary battery according to the present invention further seals the electrode assembly and the battery shell through the at least one through hole for sealing in addition to the sealing portion at the edge of the shell of the battery, thereby preventing the electrode assembly from moving inside the battery shell, Or the like can be improved. Particularly, when the battery is used as a power source for a middle- or large-sized device such as a battery automobile having a large external impact or vibration, internal short-circuit due to the flow of the electrode assembly and the risk of generation of heat and fire can be prevented and safety can be greatly improved.

The shape of the through-hole is not particularly limited, and may be formed in various shapes such as a circular shape, an elliptical shape, a curvilinear shape processed to have a curvature at a vertex, or a square, a triangle, or the like. However, in order to prevent the electrode or the separator included in the electrode assembly from being torn or damaged, it is preferable to form the through-hole in a shape having no corner or angle. Therefore, the through-hole is preferably formed in a circular shape.

Also, the size and number of the through-holes are not particularly limited, and various designs can be made depending on the use and shape of the battery. However, if the size of the through-hole is too large or the number of the through-holes is too large, the through-hole may be formed in a minimum size and in a number that can fix the battery outer case desirable.

More preferably, the entire area occupied by the through-hole may be configured to occupy from 2% to 20% with respect to the plane of the electrode assembly. If the ratio of the through holes is out of the above range, the capacity of the battery may be reduced. If the ratio is not reached, it is difficult to effectively fix the electrode assembly to the battery outer case.

In an embodiment of the present invention, a plurality of through-holes having a small size may be uniformly distributed on the electrode assembly within the range of the area ratio as described above. The through- Two through holes are formed at both end portions symmetrical to each other in the direction of the electrode assembly, so that the electrode assembly and the battery outer casing can be fixed by forming the minimum through holes.

At this time, it is preferable that the area of one through hole is formed to be 1% to 10% based on the plane area of the whole electrode assembly.

However, for convenience of the process, in the case where only two through-holes are formed at both ends which are symmetrical with respect to the longitudinal direction with respect to the center of the electrode assembly, that is, the center of gravity of the electrode assembly, For example, the through-holes may be formed at positions spaced apart by L / 6 length from both ends with respect to the length L in the longitudinal direction of the electrode assembly.

The through-hole may be formed with a through-hole through which the electrode assembly including the plurality of electrodes and the separator is assembled once, or may be formed through an electrode and a separator, which have the through- It is also possible to produce an electrode assembly in which a sphere is formed.

The electrode assembly of the present invention includes at least one through-hole at the inside thereof, thereby fixing the electrode assembly and further enhancing the impregnation property of the electrolyte.

In general, the impregnation property of an electrolyte is difficult to impregnate the electrolyte solution toward the inside of the electrode assembly, but impregnability is poor. However, since the electrode assembly of the present invention includes at least one through hole, the electrolyte can penetrate through the electrode assembly So that the electrolyte solution impregnation property of the electrode assembly can be greatly increased.

Meanwhile, the shape of the electrode assembly according to the present invention is not particularly limited, and may be a jelly roll type electrode assembly having a structure in which a long sheet-shaped anode and a cathode are wound with a separator interposed therebetween; A plurality of stacked unit cells each including a positive electrode, a negative electrode, and a separator, each having a plurality of unit cells formed by the same or different electrodes at both ends of a long film type separator, Assembly; A Z-stack & folding type electrode assembly in which the long film type separation membrane is wound in a zigzag direction; An electrode assembly such as a stacked electrode assembly having a structure in which a plurality of unit cells are stacked.

The present invention provides a secondary battery including the electrode assembly and a through-sealing part formed by further sealing a battery casing at a through-hole of the electrode assembly.

After the electrode assembly is housed in the battery case, the secondary battery is thermally fused with a sealing portion at a peripheral edge of the battery casing by a heat-sealing jig and a battery casing at a portion where the through-hole is located on the electrode assembly to form the through- can do.

The formation of the through-hole sealing portion may be performed using a heat-sealing jig configured to be thermally press-bonded to the same portion as the shape and position of the through-hole located on the electrode assembly, but the present invention is not limited thereto.

In this case, the secondary battery may be a secondary battery in which the cathode lead and the anode lead protrude in the same direction, or may be a secondary battery protruded in a direction in which the cathode lead and the anode lead are opposite to each other.

The battery casing may have an electrode assembly accommodating space in which a space is formed to accommodate the electrode assembly, the accommodating space may be formed either in the upper portion or the lower portion, or the accommodating space of the electrode assembly may be formed in both the upper portion and the lower portion.

Meanwhile, a known exterior material can be used as the exterior material for the pouch. For example, the exterior material is preferably a pouch type exterior material in the form of a laminate sheet including a metal layer and a resin layer. Particularly, a pouch-type sheathing material of an aluminum laminate sheet is preferable. The laminate sheet is composed of an outer coating layer of a polymer film, a barrier layer of a metal foil, and an inner sealant layer of a polyolefin series, and the outer coating layer must have excellent resistance to external environment, . In this respect, a stretched nylon film or polyethylene terephthalate (PET) can be preferably used as the polymer resin of the outer resin layer. The barrier layer may preferably be made of aluminum so as to exhibit a function of improving the strength of the battery case, in addition to a function of preventing the inflow or outflow of foreign substances such as gas, moisture and the like. The inner sealant layer may preferably be a polyolefin resin having a low hygroscopicity and not being swollen or corroded by an electrolytic solution in order to suppress the penetration of an electrolytic solution due to its heat sealability (thermal adhesiveness), and more preferably, Polypropylene (cPP) can be used.

Further, the outer coating layer and the inner sealant layer may be formed of two or more layers. For example, the outer coating layer may be composed of a PET / ONy layer and the inner sealant layer may be formed of a double structure such as PPa (acid modified PP / cPP) But is not limited thereto.

The electrode lead may be formed of at least one metal selected from the group consisting of aluminum, stainless steel, copper, nickel, titanium, tantalum and niobium in the case of the anode, but is not limited thereto.

When the electrode lead is a negative electrode, for example, at least one metal selected from the group consisting of copper, nickel, stainless steel, and alloys thereof is preferable, but is not limited thereto. The bonding method may be a known method such as laser or ultrasonic welding, and is not particularly limited.

The secondary battery according to the present invention can be used not only in a battery cell used as a power source of a small device but also as a unit cell in a middle or large battery module or a battery pack including a plurality of battery cells that can be used as a power source for a medium- Can be preferably used.

The medium and large devices include a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric motorcycle including E-bike, E-scooter; Electric Golf Carts; Electric truck; Electric commercial vehicle; And a power storage system, but the present invention is not limited thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto.

3 is a schematic exploded perspective view of a secondary battery according to an embodiment of the present invention.

The pouch type battery of FIG. 3 is substantially the same as the conventional pouch type battery except for the characteristic features of the present invention, so that the description of the remaining matters except for the characteristic features of the present invention can be omitted .

Referring to FIG. 3, the pouch-type secondary battery of the present invention includes an electrode assembly 10 having a plurality of through-holes 40 and a battery shell 50.

3, two through-holes 40 may be formed at symmetrical positions of both end portions with respect to the longitudinal direction of the electrode assembly, but the present invention is not limited thereto and can be freely designed by those skilled in the art Of course.

The battery outer sheath 50 included in the present invention can be a conventionally known pouch-type battery outer sheath.

FIGS. 4 and 5 are perspective views of a secondary battery in which an electrode assembly is housed and a battery casing is sealed. FIG.

Referring to FIG. 4, the secondary battery according to the present invention may further include a through-hole sealing portion 40 by thermally sealing the portion of the battery casing contacting the through-hole portion formed on the accommodated electrode assembly, The battery exterior material is fully fixed and integrated.

The additional sealing step for forming the through-hole sealing part is not limited in particular. The sealing part may be sealed at the same time when the corner sealing part of the battery exterior material is sealed to form the through-hole sealing part. Alternatively, after the activation step of the secondary battery is performed, It may be formed by sealing.

The through-hole sealing portion may be formed by using a jig formed to apply heat and pressure to the battery casing corresponding to the position where the through hole of the electrode assembly is formed, but the present invention is not limited thereto.

3 is a perspective view of a secondary battery in which a positive electrode lead 20 and a negative electrode lead 30 are protruded in the same direction and in which a storage portion of the electrode assembly is formed only on the outer surface of the lower battery. The negative electrode lead 30 protruding in different directions, and the accommodating portion of the electrode assembly is formed on both the lower and upper battery shells.

형태로 형성함이 바람직할 수 있으나 이에 한정되는 것은 아니다.
The secondary battery according to the present invention may be provided with concavities and convexities that are recessed by sealing at a portion of the through-hole sealing portion. In order to prevent the pouch-type electrode assembly from being damaged,

But it is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the following examples are intended to illustrate the effects of the present invention, and the scope of the present invention is not limited thereto.

Example

As shown in FIG. 3, a circular through-hole having a size of 3% of a plane of the electrode assembly was formed as an electrode having two through-holes at positions spaced by 1/6 of the length of the electrode assembly from both ends of the electrode assembly Assembly.

The battery case was housed in a battery case, and a corner sealing portion of the battery casing and a position of the through-hole were thermally fused by using a heat fusion jig to manufacture a secondary battery including a through-hole sealing portion.

Comparative Example

A battery was manufactured in the same manner as in the above example except that the through-hole and the through-hole sealing portion were not formed.

Experimental Example

The front drop test was performed on the batteries manufactured in Examples and Comparative Examples, and the results are shown in Table 1 below.

In this experiment, 20 cells were repeatedly performed. In the forward drop test, the process of dropping free from the height of 180 cm on the iron plate was performed 100 times so that the electrode terminal portion was downward.

Number of batteries shorted when dropped Example 0 Comparative Example 15

As shown in Table 1, the batteries of the examples according to the present invention did not cause a short circuit in all 20 batteries in the drop test. That is, since the electrode assembly and the battery casing are formed with additional through-sealing portions, the electrode assembly does not flow even when the battery assembly is dropped, thereby preventing internal short-circuiting of the secondary battery.

On the other hand, in most of the batteries according to the comparative example, the electrode assembly inside the battery exterior material was detached or flowed at about 85 drops, and deformation and internal short circuit of the battery were confirmed. In addition, in the battery of the comparative example, it was confirmed that the amount of the electrolyte injected during the electrolyte injection process was significantly lower than the target main liquid amount. That is, the impregnated amount of the electrolyte solution by the electrode assembly at the same time condition (5 minutes) after the injection of the electrolyte was compared, and as a result, the comparative example showed about 60% impregnation rate as compared with the battery of the example.

Therefore, it can be seen that the battery of the comparative example takes much longer time to exhibit the same electrolyte impregnation amount, which means that the battery manufacturing process time should be prolonged for a long time.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. The scope of the present invention should be interpreted based on the scope of the following claims, and all technical ideas within the scope of equivalents thereof should be interpreted in accordance with the following claims: It is to be understood that the invention is not limited thereto.

10 electrode assembly, 20 positive electrode lead, 30 negative electrode lead, 40 through sealing portion, 50 battery exterior member

Claims (12)

In the electrode assembly comprising a plurality of anodes, cathodes and separators,
And a through-hole formed at the same position on the anode, the cathode, and the separator,
Wherein the through-holes are formed along a central portion in a long side direction of the electrode assembly or along a central portion in a short side direction of the electrode assembly,
The total area occupied by the through hole is an electrode assembly, characterized in that 2% to 20% of the planar area of the electrode assembly.
The method according to claim 1,
The through hole is an electrode assembly, characterized in that formed in any one shape selected from the group consisting of a curvature angular, rectangular, triangular, rounded, elliptical, vertices have curvature.
The method according to claim 1,
The through hole is an electrode assembly, characterized in that formed in a circular shape.
The method according to claim 1,
The through hole is an electrode assembly, characterized in that formed in the same shape.
The method according to claim 1,
The electrode assembly is an electrode assembly, characterized in that any one selected from the structure of the jelly-roll type, stack type, stack / folding type, Z-stack / folding type.
An electrode assembly according to any one of claims 1 to 5; Pouch type battery exterior materials; And Pouch type secondary battery comprising a through-sealing portion.
The method according to claim 6,
Wherein the pouch-shaped battery outer casing comprises a structure of an inner resin layer, a metal thin film, and an outer resin layer.
The method according to claim 6,
The through-sealing portion of the pouch type secondary battery, characterized in that formed by sealing the corresponding portion of the pouch-type exterior material covering the through-hole formed on the electrode assembly.
A secondary battery module or battery pack comprising at least one pouch type secondary battery according to claim 6.
The method of claim 9,
The secondary battery module or battery pack is used as a power source for a medium and large device, and the medium and large device includes a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric motorcycle including E-bike, E-scooter; Electric Golf Carts; Electric truck; Electric commercial vehicle; Or secondary battery module or battery pack, characterized in that any one of the system for power storage.
Storing an electrode assembly having a through hole at the same position on an anode, a cathode, and a separation membrane in a pouch-shaped battery outer casing made of an inner resin layer, a metal thin film, and an outer resin layer; And
And further sealing the pouch-type battery packaging material at a position corresponding to the through hole to form a through sealing part.
Wherein the through-holes are formed along a central portion in a long side direction of the electrode assembly or along a central portion in a short side direction of the electrode assembly,
Wherein the total area occupied by the through-holes is 2% to 20% of a plane area of the electrode assembly.
The method of claim 11,
Wherein the through-sealing part is manufactured using a heat-sealing device having a pressing part corresponding to the position and shape of the through-hole so as to press the corresponding part.

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