RECHARGEABLE BATTERY

An aspect of the present invention is to provide a rechargeable battery that implements a high output of an electrode assembly by reducing electrical resistance at a connection portion of a uncoated portion and a lead tab. A rechargeable battery according to an embodiment of the present invention includes: an electrode assembly wound by arranging a separator between electrodes; a lead tab connected to the electrode; and a case which accommodates the electrode assembly and of which the lead tab is drawn to the outside, and the lead tab includes a first tab formed with a first width and a first thickness and connected to an uncoated portion of the electrode, and a second tab formed with a second width equal to or less than the first width and a second thickness equal to or more than the first thickness, and connected to the first tab.

TECHNICAL FIELD

The present disclosure relates to a rechargeable battery that draws a lead tab connected to an uncoated portion of an electrode to the outside of a case.

BACKGROUND ART

As technology development and demand for mobile devices increase, a demand for rechargeable batteries as energy sources is rapidly increasing. The rechargeable battery is a battery hat repeatedly performs charging and discharging unlike a primary battery.

Small-capacity rechargeable batteries are used in small electronic devices that can be portable, such as a mobile phone, a laptop computer and a camcorder, and large-capacity rechargeable batteries can be used as a power source for driving a motor for a hybrid vehicle and an electric vehicle.

For example, the rechargeable battery includes an electrode assembly performing charging and discharging operations, a case accommodating the electrode assembly, and a lead tab drawing the electrode assembly to the outside of the case. The electrode assembly is formed by welding the lead tab to an uncoated portion and winding an electrode and a separator.

However, in the electrode assembly, resistance increases at a portion where the uncoated portion and the lead tab are connected to interfere with a high output of the electrode assembly.

DISCLOSURE

Technical Problem

An aspect of the present invention is to provide a rechargeable battery that implements a high output of an electrode assembly by reducing electrical resistance at a connection portion of a uncoated portion and a lead tab.

Technical Solution

A rechargeable battery according to an embodiment of the present invention includes: an electrode assembly wound by arranging a separator between electrodes; a lead tab connected to the electrode; and a case which accommodates the electrode assembly and of which the lead tab is drawn to the outside, and the lead tab includes a first tab formed with a first width and a first thickness and connected to an uncoated portion of the electrode, and a second tab formed with a second width equal to or less than the first width and a second thickness equal to or more than the first thickness, and connected to the first tab.

The second thickness may be larger than the first thickness.

The first tab may be connected to the uncoated portion with one surface through a surface contact, and partially protruded to the outside of the uncoated portion, and the second tab may be connected to one surface of the first tab through the surface contact.

The second tab may be connected to a side end of the uncoated portion with a side surface in a separation state or a partial contact state.

The second tab may be further connected to the side end of the uncoated portion with the side surface through the surface contact.

The first tab may be connected to a termination uncoated portion of a first electrode (e.g., anode) and a termination uncoated portion of a second electrode (e.g., cathode) among the electrodes.

The first tab may be connected to the leading uncoated portion and the termination uncoated portion of the first electrode (e.g. anode), and connected to the leading uncoated portion and the termination uncoated portion of the second electrode (e.g., cathode) among the electrodes.

The first tab may be further connected to an intermediate uncoated portion of the first electrode, and further connected to the intermediate uncoated portion of the second electrode.

The first tab may be connected to the leading uncoated portion of the first electrode (e.g., anode) and the termination uncoated portion of the second electrode (e.g., cathode) among the electrodes.

The first tab may be connected to the termination uncoated portion of the first electrode (e.g., anode) and the leading uncoated portion of the second electrode (e.g., cathode) among the electrodes.

The first tab may be connected to the intermediate uncoated portion of the first electrode (e.g., anode) and the leading uncoated portion and the termination uncoated portion of the second electrode (e.g., cathode) among the electrodes.

The first tab may be connected to the leading uncoated portion and the termination uncoated portion of the first electrode (e.g., anode) and may be further connected to the intermediate uncoated portion of the second electrode (e.g., cathode) among the electrodes.

Advantageous Effects

According to an embodiment of the present invention, since a lead tab is formed by first and second tabs (inner and outer tabs), and a first tab is formed with a first width and a thickness, a second tab is formed with a second thickness equal to or more than the first thickness and a second width equal to or less than the first width, the first tab (inner tab) is connected to an uncoated portion, and the second tab (outer tab) is connected to the first tab, electrical resistance can be reduced at a connection portion of the uncoated portion and the lead tab. That is, a high output of an electrode assembly can be implemented.

Further, according to an embodiment, a side surface of the second tab (outer tab) is further connected to a side end of the uncoated portion in a separation state or a partial contact state to facilitate a work process. Further, according to an embodiment, since the side surface of the second tab (outer tab) is further connected to the side end of the uncoated portion through a surface contact, the electrical resistance can be further reduced at the connection portion of the uncoated portion and the lead tab.

MODE FOR INVENTION

FIG. 1is an exploded perspective view illustrating a rechargeable battery according to a first embodiment of the present invention andFIG. 2is a cross-sectional view taken along line II-II ofFIG. 1. Referring toFIGS. 1 and 2. the rechargeable battery according to the first embodiment includes an electrode assembly110charging and discharging current, a lead tab connected to the electrode assembly110, and a case (as an example, referred to as a “pouch120”) embedding the electrode assembly110and an electrolyte. The lead tab is drawn to the outside of the pouch120.

The electrode assembly110is formed to be accommodated in an internal space of the pouch120by arranging and winding electrodes, i.e., a first electrode (for convenience, referred to as an “anode”)11and a second electrode (for convenience, referred to as a “cathode”)12on both sides with a separator13interposed therebetween, and then pressing a wound outer peripheral surface.

The lead tab includes a first lead tab (for convenience, referred to as an “anode tab”)14and a second lead tab (for convenience, referred to as a “cathode tab”)15. The anode tab14is electrically connected to the anode11and the cathode tab15is electrically connected to the cathode12.

FIG. 3is a plan view of both surfaces unfolding and illustrating an electrode applied to an electrode assembly ofFIG. 1andFIG. 4is a side view of the electrode illustrated inFIG. 3. For convenience, the separator13is omitted inFIGS. 3 and 4.

Referring toFIGS. 3 and 4, the anode11includes 11thand 12thcoated portions11aand11bformed by applying a positive active material onto both surfaces of a current collector11cof a metal thin plate, and first and second uncoated portions (as an example, leading and termination uncoated portions)11dand11eset as the current collector11cexposed to a leading end and a termination end of the current collector11cbecause the positive active material is not applied. For example, the current collector11cof the anode11may be made of aluminum (Al), and the anode tab14connected to the anode11may also be made of aluminum (Al).

The cathode12includes 21stand 22thcoated portions12aand12bformed by applying a negative active material onto both surfaces of a current collector12cof the metal thin plate, and third and fourth uncoated portions (as an example, leading and termination uncoated portions)12dand12eset as the current collector12cexposed to the leading end and the termination end of the current collector12cbecause the negative active material is not applied. For example, the current collector12cof the cathode12may be made of copper (Cu), and the cathode tab15connected to the cathode12may also be made of copper (Cu).

The anode and cathode tabs14and15includes a first tab (for convenience, referred to as inner tabs141and151) and a second tab (for convenience, referred to as outer tabs142and152)

The inner tabs141and151are connected to the anode and cathode11and12by ultrasonic welding or laser welding, and drawn to the outside of the electrode assembly110and arranged inside the pouch120.

The outer tabs142and152are connected to the inner tabs141and151by the ultrasonic welding or laser welding outside the electrode assembly110, and drawn to the outside of the pouch120. That is, the outer tabs142and152are extended inside and outside the pouch120.

FIG. 5is a cross-sectional view taken along line V-V ofFIG. 3. Referring toFIGS. 1 to 5, in the anode and cathode tabs14and15, the inner tabs141and151are welded to the termination uncoated portions11eand12eof the anode and cathode11and12and drawn to the outside of the electrode assembly110, and the outer tabs142and152are welded to the inner tabs141and151outside the electrode assembly110.

For convenience, the cathode tabs15are not illustrated and the anode tab14is illustrated. The inner tabs141and151are formed with a first width W1and a first thickness t11, and connected to the termination uncoated portions11eand12eof the anode and cathode11and12. The inner tabs141and151are connected to one surface of each of the termination uncoated portions11eand12ethrough the surface contact and partially protruded outside the termination uncoated portions11eand12e.

The outer tabs142and152are formed with a second width W2equal to or less than the first width W1(W2≤W1) and a second thickness t2equal to or more than the first thickness t1(t1≤t2), and connected to the inner tabs141and151. The outer tabs142and152are formed with a second width W2equal to or less than the first width W1(W2≤W1) and a second thickness t2equal to or more than the first thickness t1(t1≤t2), and connected to the inner tabs141and151. In order to reduce current resistance, the second thickness t2may also be larger than the first thickness t1′ (t1<t2)′

Since the inner tabs141and151are welded to the termination uncoated portions11eand12ewith the first width W1which is a sufficient size through the surface contact, the current resistance which flows between the termination uncoated portions11eand12eand the inner tabs141and151may be reduced.

In addition, since the outer tabs142and152are welded to the inner tabs141and151with the second thickness t2equal to or more than the first thickness t1(t1≤t2) through the surface contact, the current resistance which flows between the inner tabs141and151and the outer tabs142and152may be reduced. That is, since the outer tabs142and152increase an outer surface area by the second thickness t2, the current resistance is reduced.

As such, since the electrical resistance is reduced in the termination uncoated portions11eand12e,connection portions of the inner tabs141and151and the outer tabs142and152, and the outer tabs142and152themselves, a high output of the electrode assembly110may be implemented.

Meanwhile, the outer tabs142and152are further connected to side ends of the termination uncoated portions11eand12ewith the side surfaces through the surface contact. That is, since the outer tabs142and152are in surface contact with the inner tabs141and151which are in surface contact with the termination uncoated portions11eand12eand in surface contact with the side surfaces of the termination uncoated portions11eand12e,contact areas of the outer tabs142and152and the termination uncoated portions11eand12eare increased.

Accordingly, the current resistance which flows between the termination uncoated portions11eand12e,and the inner tabs141and151and the outer tabs142and152is further reduced, and further, the high output of the electrode assembly110may be further implemented.

In this case, the termination uncoated portions11eand12e,and the connection portions of the inner tabs141and151and the outer tabs142and152are electrically insulated by the separator13. In addition, the termination uncoated portions11eand12eand the inner tabs141and151are welded to each other, and as a result, a mutual contact may also be firmly formed.

FIG. 6illustrates another form of the cross-sectional view taken along line V-V ofFIG. 3. When described by referring toFIGS. 3 and 6, the outer tabs142and152may also be further connected to the side ends of the termination uncoated portions11eand12ewith the side surfaces in a separation state or a partial contact state. In this case, a connection task process becomes easier than the case where the outer tabs142and152described above are in surface contact with the side ends of the termination uncoated portions11eand12ewith the side surfaces.

Although not illustrated, the outer tab may be in surface contact with an opposite surface of the inner tab. In this case, since the outer tab and the side surface of the termination uncoated portion are not in surface contact with each other, a contact area formed between the termination uncoated portion and the outer tab is smaller than the contact area formed inFIG. 5.

Referring back toFIGS. 1 and 2, the pouch120accommodates the electrode assembly110, and thermally fuses an outer portion to form the rechargeable battery. In this case, the outer tabs142and152of the anode and cathode tabs14and15are covered with insulating members143and153, and drawn to the outside of the pouch120through a fused portion.

That is, the insulating members143and153electrically insulate the outer tabs142and152of the anode and cathode tabs14and15, and electrically insulates the outer tabs142and152of the anode and cathode tabs14and15, and the pouch120.

The pouch120may be formed in a multi-layered sheet structure covering an exterior of the electrode assembly110. For example, the pouch120includes a polymer sheet121, and a nylon sheet122and a metal sheet123.

The polymer sheet121forms an inner surface of the pouch120, and insulates and thermally fuses, and the nylon sheet122forms an outer surface of the pouch120and performs a protection action, and the metal sheet123provides a mechanical strength to the pouch120.

The nylon sheet122may also be formed by a polyethyleneterephthalate (PET) sheet or a PET-nylon composite sheet. The metal sheet123is interposed between the polymer sheet121and the nylon sheet122, and may also be formed by an aluminum sheet as an example.

Further, the pouch120includes a first enclosure201and a second enclosure202. The first and second enclosures201and202may be formed by the polymer sheet121, the nylon sheet122, and the metal sheet123of the same layer structure.

For example, the first enclosure201is formed in a concave structure so as to accommodate the electrode assembly110. The second enclosure202covers the electrode assembly110accommodated in the first enclosure201, and is formed in parallel so as to be thermally fused to the first enclosure201outside the electrode assembly110.

Although not illustrated, the second enclosure may be integrally connected to the first enclosure in one direction of fourth directions on a plane, and separated in three remaining directions, and as a result, a sealability may be further enhanced in one connected direction.

Hereinafter, various embodiments of the present invention will be described. For convenience, a description of the same configuration as the first embodiment and a pre-described embodiments will be omitted and different configurations will be described.

FIG. 7is a plan view of both surfaces unfolding and illustrating an electrode applied to an electrode assembly of a rechargeable battery according to a second embodiment of the present invention. Referring toFIG. 7, in the second embodiment, in the anode tabs14and16of the anode61, the inner tabs141and161are connected to the termination uncoated portion11eand the leading uncoated portion11dof the anode61respectively. That is, the anode tabs14and16form multiple tabs. In addition, in the cathode tabs15and17of the cathode62, the inner tabs151and171are connected to the termination uncoated portion12eand the leading uncoated portion21dof the cathode62, respectively. That is, the cathode tabs15and17form multiple tabs.

As such, two anode tabs14and16are connected to the termination and leading uncoated portions11eand11dof the anode61, respectively, and two cathodes tabs15and17are connected to the termination and leading uncoated portions12eand12dof the cathode62, respectively. Accordingly, since each of the anode tabs14and16and the cathode tabs15and17are provided in two, the electrical resistance is further reduced to more effectively implement the high output of the electrode assembly as compared with the first embodiment.

That is, as compared with the first embodiment, since the electrical resistance is further reduced in the leading uncoated portions11dand12d.connection portions of the inner tabs161and171and the outer tabs162and172, and the outer tabs162and172themselves, which are further provided, the high output of the electrode assembly may be more effectively implemented.

FIG. 8is a plan view of both surfaces unfolding and illustrating an electrode applied to an electrode assembly of a rechargeable battery according to a third embodiment of the present invention. Referring toFIG. 8, in the third embodiment, an anode71and a cathode72further include intermediate uncoated portions11fand12fas compared with the structures of the anode and cathode61and62in the second embodiment.

In the anode tabs14,16, and18of the anode71the inner tabs141,161, and181are connected to the termination uncoated portion11e,the leading uncoated portion11d,and the intermediate uncoated portion11fof the anode71, respectively. In addition, in the cathode tabs15,17, and19of the cathode72, the inner tabs151,171, and191are connected to the termination uncoated portion12e,the leading uncoated portion12d,and the intermediate uncoated portion12fof the cathode72, respectively.

As such, three anode tabs14,16, and18are connected to the termination, leading, and intermediate uncoated portions11e,11d,and11fof the anode71, respectively, and three cathodes tabs15,17, and19are connected to the termination, leading, and intermediate uncoated portions12e,12d,and12fof the cathode72, respectively.

Accordingly, since each of the anode tabs14,16, and18and the cathode tabs15,17, and19are provided in three, the electrical resistance is reduced to more effectively implement the high output of the electrode assembly as compared with the second embodiment.

That is, as compared with the second embodiment, since the electrical resistance is further reduced in the intermediate uncoated portions11fand12f,connection portions of the inner tabs181and191and the outer tabs182and192, and the outer tabs182and192themselves, the high output of the electrode assembly may be more effectively implemented.

FIG. 9is a plan view of both surfaces unfolding and illustrating an electrode applied to an electrode assembly of a rechargeable battery according to a fourth embodiment of the present invention. Referring toFIG. 9, in the fourth embodiment, in the anode tab16of the anode63, the inner tab161is connected to the leading uncoated portion11dof the anode63. In addition, in the cathode tab15of the cathode64, the inner tab151is connected to the termination uncoated portion12eof the cathode64.

As such, one anode tab16is connected to the leading uncoated portion11dof the anode63and one cathode tab15is connected to the termination uncoated portion12eof the cathode64. Accordingly, each of the anode tab16and the cathode tab15are provided in one, and the anode tab16and the cathode tab15are arranged to cross on the leading end and the termination end, and as a result, as compared with the second embodiment (seeFIG. 7), the anode and cathode16and15are easily arranged, and the electrically resistance such as the first embodiment (seeFIG. 3) is reduced to effectively implement the high output of the electrode assembly.

That is, the electrical resistance is reduced in the leading uncoated portion11d,the connection portion of the inner tab161and the outer tab162, the outer tab162itself in the anode63and in the termination uncoated portion12e,the connection portion of the inner tab151and the outer tab152, and the outer tab152itself in the cathode64, and as a result, the high output of the electrode assembly may be effectively implemented as in the first embodiment.

FIG. 10is a plan view of both surfaces unfolding and illustrating an electrode applied to an electrode assembly of a rechargeable battery according to a fifth embodiment of the present invention. Referring toFIG. 10, in the fifth embodiment, in the anode tab14of the anode65, the inner tab141is connected to the termination uncoated portion11eof the anode65. In addition, in the cathode tab17of the cathode66, the inner tab171is connected to the leading uncoated portion12dof the cathode66.

As such, one anode tab14is connected to the termination uncoated portion11e of the anode65and one cathode tab17is connected to the leading uncoated portion12dof the cathode66. Accordingly, each of the anode tab14and the cathode tab17are provided in one, and the anode tab14and the cathode tab17are arranged to cross on the termination end and the leading end, and as a result, as compared with the second embodiment (seeFIG. 7), the anode tab14and the cathode tab17are easily arranged, and the electrically resistance such as the first embodiment (seeFIG. 3) is reduced to effectively implement the high output of the electrode assembly.

That is, the electrical resistance is reduced in the termination uncoated portion11e,the connection portion of the inner tab141and the outer tab142, the outer tab142itself in the anode65and in the leading uncoated portion12d,the connection portion of the inner tab171and the outer tab172. and the outer tab172itself in the cathode66, and as a result, the high output of the electrode assembly may be effectively implemented as in the first embodiment.

FIG. 11is a plan view of both surfaces unfolding and illustrating an electrode applied to an electrode assembly of a rechargeable battery according to a sixth embodiment of the present invention. Referring toFIG. 11, in the fifth embodiment, in the anode tab18of the anode73, the inner tab181is connected to the intermediate uncoated portion11fof the anode73. In addition, in the cathode tabs15and17of the cathode74. the inner tabs151and171are connected to the termination uncoated portion12eand the leading uncoated portion12dof the cathode74, respectively.

As such, one anode tab18is connected to the intermediate uncoated portion11fof the anode73and two cathode tabs15and17are connected to the termination and leading uncoated portions12eand12dof the cathode74, respectively. Accordingly, since there is one anode tab18, and there are two cathode tabs15and17the electrical resistance is further reduced in the cathode74to more effectively implement the high output of the electrode assembly as compared with the first embodiment.

That is, the electrical resistance is reduced in the intermediate uncoated portion11f, the connection portion of the inner tab181and the outer tab182, the outer tab182itself in the anode73and in the termination and leading uncoated portion12eand12d,the connection portions of the inner tabs151and171and the outer tabs152and172, and the outer tabs152and172themselves in the cathode74, and as a result, the high output of the electrode assembly may be effectively implemented

FIG. 12is a plan view of both surfaces unfolding and illustrating an electrode applied to an electrode assembly of a rechargeable battery according to a seventh embodiment of the present invention. Referring toFIG. 12, in the seventh embodiment, in the anode tabs14and16of the anode75, the inner tabs141and161are connected to the termination and leading uncoated portions11eand11dof the anode75, respectively. In addition, in the cathode tab19of the cathode76. the inner tab191is connected to the intermediate uncoated portion12fof the cathode76.

As such, two anode tabs14and16are connected to the termination and leading uncoated portions11eand11dof the anode75, respectively, and one cathodes tab19is connected to the intermediate uncoated portions12fof the cathode76. Accordingly, since there are two anode tabs14and16, and there is one cathode tab19, the electrical resistance is further reduced in the anode75to more effectively implement the high output of the electrode assembly as compared with the first embodiment.

That is, the electrical resistance is reduced in the termination and leading uncoated portions11eand11d,the connection portions of the inner tabs141and161and the outer tabs142and162, the outer tabs142and162themselves in the anode75and in the intermediate uncoated portion12f,the connection portion of the inner tab191and the outer tab192, and the outer tab192itself in the cathode76, and as a result, the high output of the electrode assembly may be effectively implemented.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.