KR20060134339A - Secondary battery - Google Patents

Abstract

Provided is a secondary battery which is inhibited in the wrinkling of the front end of an electrode plate in case of the winding of an electrode group to a core and is enhanced in interface uniformity. The secondary battery comprises an electrode group which comprises a separator, and an electrode group comprising a positive electrode plate and a negative electrode plate which is arranged at both sides of the separator; a case which accommodates the electrode group; and a cap assembly which is combined with the case to seal it and is combined with a terminal connected with the electrode group, wherein the front end(A) of at least one electrode plate(11) between the positive electrode plate and the negative electrode plate has a thickness different from the thickness of other region(a). Preferably the front end of at least one electrode plate between the positive electrode plate and the negative electrode plate is thicker than other region.

Description

Secondary Battery {SECONDARY BATTERY}

1 is a cross-sectional view of a rechargeable battery according to an exemplary embodiment of the present invention.

2 is a partially exploded perspective view of a rechargeable battery according to an exemplary embodiment of the present invention.

3A and 3B are diagrams illustrating in detail a pole plate of a rechargeable battery according to an exemplary embodiment of the present invention.

4 is a cross-sectional view illustrating in detail a pole plate of a rechargeable battery according to an exemplary embodiment of the present invention.

The present invention relates to a secondary battery, and more particularly, to a secondary battery having improved interfacial characteristics of the battery.

A secondary battery is a battery that can be charged and discharged unlike a primary battery that cannot be charged. In the case of a low-capacity battery in which one battery cell is packaged in a pack form, a portable electronic device such as a phone, a notebook computer, or a camcorder In the case of a large capacity battery in a battery pack unit, which is used in equipment and connected to dozens of battery cells, it is widely used as a power source for driving a motor of a hybrid vehicle.

The secondary batteries are manufactured in various shapes, and typical shapes include cylindrical and rectangular shapes, and an electrode group having a separator formed as an insulator is installed in a case between the two bands and a negative electrode plate. The battery is configured by installing a cap assembly having external terminals formed on the case.

The positive and negative electrode plates are formed of a coating portion coated with an active material on a current collector and an uncoated non-coating portion, and the positive and negative electrode non-coating portions have a conductive tab as a current collector for the current generated from the positive and negative electrode plates, respectively. taps are attached to each other, and the conductive tabs are attached to the electrode group by welding or the like to induce currents generated in the positive and negative electrode plates to the positive and negative electrode terminals, respectively.

Here, in the current collector structure of the secondary battery, in the case of a high output secondary battery, the battery is manufactured in a jellyroll form in which the electrode group is wound in a vortex phase, wherein the electrode group is in contact with the core to which the electrode group is wound for the first time. There is a problem in that the pole plate is wrinkled.

In other words, in order to wind the electrode group on the core, the first tip of the electrode group must be entered between the core and the winding rolls in contact with the core. In this process, the first tip of the electrode group is crumpled due to the speed difference between them. As a result, the electrode group is wound around the core in a crumpled state, thereby degrading the interface uniformity of the electrode group.

This problem is particularly acute for high-capacity secondary batteries, such as for HEVs (hybrid electric vehicles) .As mentioned, very thin pole plates are used to wound the cores in the form of jelly rolls to achieve high output capacity, which makes the poles more wrinkled. Occurs badly.

Therefore, the present invention is to solve the above problems, an object of the present invention is to provide a secondary battery that can improve the interface uniformity of the battery by preventing the tip of the pole plate when the electrode group to the core winding.

In order to achieve the above object, the secondary battery of the present invention is a secondary battery in which an electrode group in which a positive electrode plate and a negative electrode plate are positioned with a separator interposed therein is provided in a case, and at least one of the positive electrode plates and the negative electrode plate has a tip end portion. The thickness of is different from the thickness of other regions.

The present invention is preferably made of a structure in which the tip thickness of the electrode plate is thicker than the thickness of other regions.

In addition, the tip of the pole plate is preferably the first tip of the pole plate wound on the core.

Accordingly, the pole plate is secured so that the crumple plate can be prevented in the process of entering the first end of the pole plate of the electrode group into the core to wind the electrode group to the core.

In addition, each electrode plate includes a current collector, a coating portion coated with an active material on the entire surface of the current collector, and an uncoated non-coating portion. The present invention provides a thickness of the tip portion of the current collector constituting the electrode plate is greater than that of other regions. It may be a thick structure.

In this case, it is preferable that the thickness of the tip portion of the current collector is thicker than the thickness of other regions.

In addition, the present invention may have a structure in which the thickness of the active material coated on the tip portion of the current collector constituting the electrode plate is different from the thickness of the active material coated on other regions.

In this case, the active material thickness of the tip portion is preferably made of a structure thicker than the thickness of the active material in the other region.

The active material forming the coating part may be attached to one or both surfaces of the current collector.

On the other hand, the present invention is a region in which each electrode plate includes a current collector and a coating portion coated with an active material on the entire surface of the current collector, and an uncoated non-coating portion, and the coating amount per unit area of the active material coated on the tip of the dust collector is different. It has more structure than the coating amount of.

The secondary battery may be used as an energy source for driving a motor of the device in a device operated by using a motor such as a hybrid electric vehicle (HEV), an electric vehicle (EV), a wireless cleaner, an electric bicycle, an electric scooter, and the like. Can be.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a rechargeable battery according to an exemplary embodiment of the present invention.

According to the above drawings, the secondary battery according to the present embodiment includes the electrode group 10 in which the positive electrode plate 11 and the negative electrode plate 12 are positioned with the separator 13 interposed therebetween, and the electrode group 10 together with the electrolyte solution. A case 20 having one end opened to accommodate the cap 20, a cap assembly 30 installed at an upper end of the opening of the case 20 through a gasket 31, and sealing the case 20, and the electrode group. The positive electrode plate 11 of FIG. 10 includes a positive electrode current collector plate 40 electrically connected to a current collector, and a negative electrode current collector plate 50 electrically connected to a current collector of the negative electrode plate 12.

The case 20 is made of a conductive metal such as aluminum, an aluminum alloy or nickel plated steel, and the shape thereof may be formed in a cylindrical or hexahedron or other shape having an inner space in which the electrode group 10 is located. have.

In addition, the cap assembly 30 includes a cap plate 32 having an external terminal 32a and a gasket 31 that insulates the case 20 from the cap plate 32 and is broken under a set pressure condition. A vent plate 33 may be further included to prevent explosion of the battery by releasing gas, which is electrically connected to the positive electrode current collector plate 40 through the lead 35. The vent plate 33 may be used in various forms without being limited to the illustrated shape as long as it can block electrical connection between the electrode assembly and the external terminal 32a through the lead 35 under a set pressure condition.

In addition, the electrode group 10 has a structure in which the positive electrode plate 11 and the negative electrode plate 12 formed by coating each active material on the current collector are laminated with the separator 13 interposed therebetween, or the positive electrode plate 11 and the separator. 13 and the negative electrode plate 12 may be formed in a jelly roll type formed by winding them in a vortex in a state where they are laminated.

In the present embodiment, as shown in FIG. 1, a case in which an electrode group wound by a jelly roll type is positioned in a cylindrical case will be described as an example.

In addition, the present embodiment will be described by way of example a structure formed along one side end of each of the electrode plates forming the electrode group, the non-coating portion in electrical contact with the current collector plate. Of course, the present invention is not limited to the above structure and can be applied regardless of the shape of the battery or the structure of the plain portion.

The state in which the electrode group 10 is wound around the core 14 is well illustrated in FIG. 2. The electrode group 10 includes a positive electrode plate 11, a negative electrode plate 12, and a separator 13 between the positive and negative electrode plates. The tip is wound by a take-up roll (not shown) in the state where the tip thereof is in contact with the cylindrical core 14 in the state where?

Accordingly, the electrode assembly constituting the secondary battery according to the present exemplary embodiment includes coating portions 11b and 12b coated with an active material on a current collector and non-coated portions 11a and 12a not coated with an active material, as shown in FIGS. 3A and 3B. The positive and negative electrode plates 11 and 12 including the electrode group 10 are stacked with the separator 13 interposed therebetween and wound around the core 14 (FIG. 2).

Each active material is coated on both surfaces of the positive electrode current collector and the negative electrode current collector, and the positive electrode plate 11 and the negative electrode plate 12 have a structure in which coating portions 11b and 12b are formed on both sides, respectively.

Here, each of the positive plates is a non-coated portion 11a in which the positive electrode active material is not coated on the current collector of the positive electrode plate 11 at the upper portion of the positive electrode plate 11 in a state in which the secondary battery is placed vertically with the cap assembly 30 facing upward. An uncoated portion 12a is formed along the longitudinal direction of (11), and in the lower part of the negative electrode plate 12, in which the negative electrode active material is not applied along the longitudinal direction of the negative electrode plate 12 as well.

In each of the pole plates 11 and 12 having the above-described structure, the secondary battery has a structure in which the stiffness of the tip portions of the pole plates 11 and 12 is reinforced to prevent wrinkles at the tip portion of the pole plates during winding to the core. have.

This will be described in detail with reference to FIG. 4 as follows. Since the structure described below is equally applied to each of the electrode plates constituting the electrode group, the following description will be given as an example of the anode plate of each electrode plate.

In addition, in the following description, the tip portion A of the pole plate is defined as meaning an area of about 10 to 100 mm from the tip of the pole plate 11 first contacting the core.

When the tip portion A has a width of 10 mm or less, its area is too small compared to the total area of each of the pole plates 11 and 12, and it is difficult to give rigidity to the pole plate when the pole plate is wound. In the case where the tip portion A has a width of 100 mm or more, the weight of the current collector of each pole plate is increased, which may cause a decrease in battery performance.

As shown in FIG. 4, the positive electrode plate 11 includes a current collector 11c and a coating portion 11b coated with an active material on the current collector 11c. According to the present embodiment, the positive electrode plate 11 is first contacted with the core. The thickness D of the current collector 11c in the region A of the tip end portion A) is thicker than the thickness d of the current collector 11c in the other region a.

The tip portion A thickness D of the current collector 11c is preferably formed at a ratio of 1.8 to the thickness d of the current collector 11c of the other region a.

Here, the thickness D 'of the coating part 11b of the current collector 11c in the area of the tip portion A of the positive electrode plate 11 is greater than the thickness d' of the coating part 11b on the other area a. The thickness of the entire positive electrode plate 11 is kept the same by forming a thickness as small as the thickness difference of the whole 11c.

In addition to the structure, the thickness D 'of the tip portion A of the current collector 11c of the positive electrode plate 11 is different by making the thickness of the coating part 11b of the current collector 11c of the positive electrode plate 11 the same. It can be formed thicker than the region (a).

Accordingly, the rigidity of the tip portion A of the positive electrode plate 11 is more secured than that of the other regions a, thereby preventing bending or wrinkling of the electrode plate 11 during the winding of the positive electrode plate 11 to the core.

In addition, according to another embodiment of the present secondary battery, in order to secure the rigidity of the tip portion A of the positive electrode plate 11, a structure having a different coating ratio of the active material coated on the current collector 11c is applied.

That is, as shown in FIG. 4, the positive electrode plate 11 according to the present embodiment includes a current collector 11c and a coating part 11b formed by coating an active material on the current collector 11c, and the current collector 11c. The coating portion 11b thickness D 'of the tip portion A has a structure thicker than the coating portion 11b thickness d' of the active material coated on the other region a.

The coating thickness (D ′) of the coating portion (11b) at the tip portion (A) of the current collector (11c) is formed at a ratio of 1.8 than the coating thickness (d ') of the coating portion (11b) in the other region (a). desirable.

Accordingly, the strength of the tip portion A of the positive electrode plate 11 first contacting the core is greater than that of the other regions a due to the difference in coating thickness of the coating portion 11b coated with the active material, so that the positive electrode plate 11 is wound around the core. It is possible to prevent the bending or wrinkle of the electrode plate 11 in the process.

On the other hand, according to another embodiment of the present secondary battery, a structure in which the coating amount of the active material applied to the coating part 11b is applied in order to secure the strength of the tip portion A of the electrode plate 11.

As shown in FIG. 4, the positive electrode plate 11 according to the present exemplary embodiment includes a current collector 11c and a coating portion 11b formed by coating an active material on the current collector 11c. The coating amount of the active material per unit area of the coating part 11b in the front end portion A of the whole 11c is larger than the coating amount of the active material per unit area in the coating part 11b of the other region (a).

Herein, the coating amount of the active material per unit area in the coating part 11b may be represented by the weight or density of the active material per unit area. Accordingly, the large amount of coating of the active material per unit area means that the active material is coated relatively in the corresponding area. High density of the active material means that the weight is large.

The coating amount of the active material per unit area in the coating portion 11b of the tip portion A of the current collector 11c is preferably formed at a ratio of 1.8 than the coating amount of the active material per unit area in the coating portion 11b of the other region. .

As described above, the coating amount of the active material at the tip portion A of the positive electrode plate 11 is larger than that of the other regions a, so that the strength of the tip portion A of the positive electrode plate 11 is relatively larger than that of the other regions a. Accordingly, the positive electrode plate 11 may be prevented from bending or wrinkling in the process of being wound on the core.

Meanwhile, a process of winding the electrode plate 11 having the rigidity of the tip portion A secured in the form of a jelly roll on the core as described above may be performed by stacking the separator 13 between the positive electrode plate 11 and the negative electrode plate 11. 14), the electrode group enters between the core 14 and a winding roll (not shown) in contact with the core to wind the electrode group. At this time, the tip of each electrode plate forming the electrode group includes the core and the winding roll. Crashes.

As described above, the tip portion A of each of the pole plates 11 and 12 has the rigidity secured to some extent, and the tip of the pole plate is prevented from being deformed, such as wrinkles, in the process of entering between the core and the take-up roll, so that the core is correctly placed. It can be wound up.

As described above, the secondary battery of the present invention can be effectively used as a battery for HEV requiring high output / large capacity, but the use thereof is not necessarily limited to HEV.

In addition, in the present embodiment, the rigid reinforcing material has been described as a structure attached to both the positive electrode plate and the negative electrode plate, but the present invention is not necessarily limited to this structure, it can be applied even when formed on at least one of the positive electrode plate, the negative electrode plate. have.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to

As described above, according to the present embodiment, the front end of the electrode plate is prevented from being deformed in the process of winding the electrode group on the core, thereby increasing the interface uniformity, thereby increasing the reliability of the product.

Claims (19)

An electrode group including a separator and a positive electrode plate and a negative electrode plate disposed on both sides of the separator, A case in which the electrode group is built in, And a cap assembly coupled to the case to seal it and coupled to a terminal connected to the electrode group. At least one of the positive electrode plate and the negative electrode plate is a secondary battery having a structure in which the thickness of the tip portion is different from the thickness of the other region. The secondary battery according to claim 1, wherein the tip portion of the electrode plate is thicker than the thickness of other regions. The secondary battery of claim 1, wherein the tip portion of the pole plate is an initial tip of the pole plate wound around the core. The secondary battery of claim 1, wherein the electrode plate is a positive electrode plate. The secondary battery of claim 1, wherein the electrode plate is a negative electrode plate. The secondary battery of claim 1, wherein the distal end portion is an area within 10 to 100 mm from the distal end of the electrode plate in contact with the core. The current collector of claim 1, wherein the electrode plate includes a current collector, a coating portion coated with an active material on the front surface of the current collector, and a non-coating portion, and the thickness of the tip portion of the current collector constituting the electrode plate is different from that of the current collector. Different secondary batteries. The secondary battery of claim 7, wherein a thickness of a tip portion of the current collector is thicker than a current collector thickness of another region. The secondary battery of claim 7, wherein a current collector thickness ratio of a region different from a tip thickness of the current collector is 1.8: 1. The secondary battery of claim 7, wherein an entire thickness of the electrode plate including the current collector is the same in a region different from the tip portion. The rechargeable battery of claim 1, wherein the electrode plate includes a current collector and a lubricant coated on the entire surface of the current collector, and the thickness of the active material coated on the tip of the current collector is different from the thickness of the active material coated on the other region. . The secondary battery of claim 11, wherein an active material thickness of the tip portion is thicker than an active material thickness of another region. The secondary battery of claim 11, wherein a thickness ratio of the active material coated on the front end of the current collector to another region is about 1.8: 1. The rechargeable battery of claim 11, wherein the active material forming the coating part is attached to one or both surfaces of the current collector. The secondary battery according to claim 11, wherein an entire thickness of the electrode plate including the current collector is the same in a region different from the tip portion. According to claim 1, wherein the electrode plate comprises a current collector and the coating portion coated with the active material and the uncoated non-coating portion on the entire surface of the current collector, the coating amount per unit area of the active material coated on the front end of the current collector in different areas Secondary battery different from the coating amount per unit area of the active material to be coated. The secondary battery of claim 16, wherein the coating amount per unit area of the active material coated on the tip of the current collector is larger than the coating amount of other regions. The secondary battery of claim 16, wherein a coating ratio of a coating amount per unit area of the active material coated on the distal end of the current collector and another region is 1.8: 1. The secondary battery of claim 1, wherein the secondary battery is for driving a motor.

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