RECHARGEABLE BATTERY AND METHOD OF MANUFACTURING THE
SAME
BACKGROUND
1. Field of the Invention
[000 11 Embodiments relate to a rechargeable battery and a method of manufacturing
the same.
2. Description of the Related Art
[0002] Unlike a primary battery that is incapable of being recharged, a rechargeable
battery may be repeatedly charged and discharged. A low-capacity rechargeable battery
may be used for a small portable electronic device, e.g., a mobile phone, a laptop
computer, andlor a camcorder. A large-capacity battery may be used as a power supply
for, e.g., driving a motor of a hybrid vehicle or the like.
[0003] A large-capacity and high power rechargeable battery using a non-aqueous
electrolyte of high energy density has been considered. The high power rechargeable
batteries may be connected to each other in series or in parallel to configure a high
power and large capacity battery module.
[0004] The rechargeable battery may include an electrode assembly including a positive
electrode, a negative electrode, and a separator interposed between the positive
electrode and the negative electrode. The positive electrode and the negative electrode
may each have a structure in which an active material is coated on a current collector
formed of metal, and on the current collector, a coated region coated with the active
material and an uncoated region without the active material are formed.
The above information disclosed in this Background section is only for
enhancement of understanding of the background of the described technology and
therefore it may contain information that does not form the prior art that is already
known in this country to a person of ordinary skill in the art.
SUMMARY
Embodiments are directed to a rechargeable battery and a method of
manufacturing the same.
The embodiments may be realized by providing a rechargeable battery including
an electrode assembly, the electrode assembly including a first electrode, a second
electrode, and a separator between the first electrode and the second electrode; and a
case accommodating the electrode assembly, wherein each of the first and second
electrodes includes a coated region having an active material layer on a current collector
and an uncoated region free of the active material layer, and in at least one electrode of
the first and second electrodes, the current collector is characterized by an x-ray
diffraction pattern in which a ratio of an FWHM of a largest peak:an FWHM of a
second largest peak of the current collector in the uncoated region is greater than a ratio
of an FWHM of a largest peak:an FWHM of a second largest peak of the current
collector in the coated region:
[0008] The ratio of the FWHM of the largest peak:the FWHM of the second largest
peak of the current collector in the uncoated region may be about 1.3 to about 1.6 times
the ratio of the FWHM of the largest peakthe FWHM of the second largest peak of the
current collector in the coated region.
[0009] In the at least one electrode, the current collector may be characterized by an xray
diffraction pattern in which a ratio of an FWHM of a largest peak-an FWHM of a
second largest peak of the current collector in the uncoated region is about 1.4 to about
2.0.
[00 lo] The current collector of the at least one electrode may have an average thickness
in the uncoated region smaller than an average thickness thereof in the coated region.
[OOl 11 In the at least one electrode, the average thickness of the current collector in the
uncoated region may be about 80 to about 95 % of the average thickness of the current
collector in the coated region.
[00 121 The current collector of each of the first electrode and the second electrode may
be characterized by an x-ray diffraction pattern in which a ratio of an FWHM of a
largest peakan FWHM of a second largest peak of the current collector in the uncoated
region is greater than a ratio of an FWHM of a largest peak:an FWHM of a second
largest peak of the current collector in the coated region.
[00 131 The uncoated regions of each of the electrodes may extend along a side end of
the respective current collectors.
[00 141 The embodiments may also be realized by providing a method of manufacturing
a rech~eableba ttery, the method comprising preparing an electrode such that
preparing the electrode includes coating an active material on a portion of a current
collector to form a coated region and a preliminary uncoated region, the preliminary
uncoated region extending along one side end of the current collector and being free of
the active material; and vibration hammering the current collector in the preliminary
uncoated region to form an uncoated region such that the current collector is
characterized by an x-ray diffraction pattern in which a ratio of an FWHM of a largest
peak:an FWHM of a second largest peak of the current collector in the uncoated region
is greater than a ratio of an FWHM of a largest peak:an FWHM of a second largest peak
of the current collector in the coated region.
[OO 151 The ratio of the FWHM of the largest peak:the FWHM of the second largest
peak of the current collector in the uncoated region may be about 1.3 to about 1.6 times
the ratio of the FWHM of the largest peak:the FWHM of the second largest peak of the
current collector in the coated region.
[00 161 The current collector may be characterized by an x-ray diffraction pattern in
which a ratio of an FWHM of a largest peak:an FWHM of a second largest peak of the
current collector in the uncoated region is about 1.4 to about 2.0.
COO1 71 The current collector may have an average thickness in the uncoated region
smaller than an average thickness thereof in the coated region. The average thickness
of the current collector in the uncoated region may be about 80 to about 95 % of the
average thickness of the current collector in the coated region.
[00 1 81 The vibration hammering may include ultrasonic vibration hammering. The
ultrasonic vibration hammering may include passing the preliminary uncoated region
along an anvil, generating ultrasonic vibrations with an ultrasonic vibration generator,
and striking the preliminary uncoated region with a horn that vibrates in response to the
ultrasonic vibrations of the ultrasonic vibration generator. The anvil may have a
cylindrical roller structure, and passing the preliminary uncoated region along the anvil
may include rolling the preliminary uncoated region along the cylindrical roller.
[00 191 The ultrasonic vibrations may have a frequency of about 8 to about 12 kHz, the
horn may strike the preliminary uncoated region with a pressure of about 0.4 to about
0.8 MPa, and the preliminary uncoated region may be passed along the anvil at a speed
of about 3 mlmin to about 7 m/min.
[0020] The method may further include pressing the coated region between pressing
rollers. Vibration hammering the current collector in the preliminary uncoated region
may occur prior to pressing the coated region. Pressing the coated region may occur
prior to vibration hammering the current collector in the preliminary uncoated region.
The method may further include drying the active material.
BRIEF DESCFUPTION OF THE DRAWINGS
[002 11 Features will become apparent to those of ordinary skill in the art by describing
in detail exemplary embodiments with reference to the attached drawings in which:
[0022] FIG. 1 illustrates a perspective view of a rechargeable battery according to an
embodiment.
[0023] FIG. 2 illustrates a cross-sectional view taken along line 11-TI of FIG. 1.
[0024] FIG. 3 illustrates a perspective view of a negative electrode according to an
embodiment.
[0025] FIG. 4 illustrates a graph showing thicknesses of a negative coated region and a
negative uncoated region according to an embodiment.
[0026] FIG. 5 illustrates a graph showing stretching ratios of a negative coated region
and a negative uncoated region according to an embodiment.
FIG. 6A illustrates a graph showing an X-ray diffraction profile of a negative
uncoated region according to an embodiment.
[0028] FIG. 6B illustrates a graph showing an X-ray diffraction profile of a negative
coated region according to an embodiment.
[0029] FIG. 7 illustrates a perspective view of a positive electrode according to an
embodiment.
[003 01 FIG. 8 illustrates a diagram showing a fabricating method of an electrode
according to an embodiment.
(003 11 FIG. 9 illustrates a diagram showing a fabricating method of an electrode
according to an embodiment.
DETAILED DESCRIPTION
[0032] Example embodiments will now be described more fully hereinafter with
reference to the accompanying drawings; however, they may be embodied in different
forms and should not be construed as limited to the embodiments set forth herein.
Rather, these embodiments are provided so that this disclosure will be thorough and
complete, and will fully convey the scope of the invention to those skilled in the art.
(00331 In the drawing figures, the dimensions of layers and regions may be exaggerated
for clarity of illustration. It will also be understood that when a layer or element is
referred to as being "on" another element, it can be directly on the other element, or
intervening elements may also be present. In addition, it will also be understood that
when an element is referred to as being "between" two elements, it can be the only
element between the two elements, or one or more intervening elements may also be
present. Like reference numerals refer to like elements throughout.
[0034] An embodiment provides an electrode applied to a positive electrode or a
.negative electrode of a rechargeable battery, the electrode including: a sheet type
current collector and an active material layer coated on the current collector, in which
the current collector includes a coated region (where the active material layer is formed)
and an uncoated region (adjacent to the coated region and fiee of active material). The
current collector in the uncoated region may have a thickness smaller than the current
collector in the coated region.
Another embodiment provides a fabricating method of an electrode, including:
vibration-hammering a preliminary uncoated region of a current collector (that includes
a coated region where an active material layer is formed and the uncoated region fiee of
active material).
[0036] Yet another embodiment provides a rechargeable battery, including: an electrode
assembly including a first electrode and a second electrode; a case having a space
housing the electrode assembly; and a cap plate covering an opening in the case. The
first electrode may include a sheet type current collector and an active material layer
coated on the current collector, the current collector including a coated region where the
active material layer is formed and an uncoated region adjacent to the coated region and
fiee of the active material layer. The current collector in the uncoated region may have
a thickness smaller than the current collector in the coated region.
[0037] FIG. 1 illustrates a perspective view of a rechargeable battery according to an
embodiment. FIG. 2 illustrates a cross-sectional view taken along line 11-11 of FIG. 1.
[0038] Referring to FIGS. 1 and 2, a rechargeable battery 101 according to an
embodiment may include an electrode assembly 10 wound with a separator 13
interposed between a positive electrode (first electrode) 11 and a negative electrode
(second electrode) 12, a case 30 (in which the electrode assembly 10 is embedded or
accommodated), and a cap plate 25 coupled with an opening of the case 30.
[0039] The rechargeable battery 101 according to the present embodiment will be
described using a lithium ion rechargeable battery having a square or hexahedral shape
as an example. However, the embodiments are not limited thereto, and may be applied
to various types of batteries, e.g., a lithium polymer battery, a cylindrical battery, or the
like.
[0040] FIG. 3 illustrates a perspective view of a negative electrode according to an
embodiment. FIG. 7 illustrates a perspective view of a positive electrode according to
an embodiment.
[004 11 As shown in FIGS. 3 and 7, the positive electrode 1 1 may include a positive
current collector 1 12 (formed of, e.g., a thin metal foil) and a positive active material
layer 1 13 (formed on the positive current collector 112). The negative electrode 12 may
include a negative current collector 12 1 and a negative active material layer 122 formed
on the negative current collector 12 1.
[0042] The positive current collector 112 may be formed in an elongated band shape
and may include a positive coated region 1 lb (where the active material layer 113 is
coated) and a positive uncoated region 1 la (adjacent to the positive coated region 1 1 b
and free of active material). The negative current collector 121 may be formed in an
elongated band shape and may include a negative coated region 12b (where the negative
active material layer 122 is coated) and a negative uncoated region 12a (free of active
material).
[0043] The positive uncoated region 1 la may be formed on one side end of the positive
current collector 1 12 along a lengthwise direction of the positive current collector 112.
The negative uncoated region 12a may be formed on another side end of the negative
current collector 121 along a lengthwise direction of the negative current collector 121.
[0044] The positive electrode 11 and the negative electrode 12 may be wound after a
separator 13, e.g., an insulator, is interposed therebetween.
[0045] However, the embodiments are not limited thereto, and the electrode assembly
may have a structure in which the positive electrode and the negative electrode (formed
of a plurality of sheets) are stacked with the separator interposed therebetween.
The case 30 may have a substantially cuboid or hexahedral shape, and an
opening may be formed at one surface or side thereof. The cap assembly 20 may
include a cap plate 25 (covering the opening of the case 30), a positive terminal 21
(protruding outside the cap plate 25 and electrically connected to the positive electrode
1 l), a negative terminal 22 (protruding outside the cap plate 25 and electrically
connected to the negative electrode 12), and a vent member 27 (having a notch 39a so
as to be broken in response to a predetermined internal pressure).
The cap plate 25 may be formed of a thin metal plate and may be fmed to the
case 30 at the opening thereof by, e.g., welding. An electrolyte injection opening (for
injecting an electrolyte) may be formed at one side of the cap plate 25, and a sealing
stopper 38 (that seals the electrolyte injection opening) may be fixed to the cap plate 25.
[0048] The positive terminal 21 may penetrate through the cap plate 25, and a first
gasket 24 (disposed above) and a second gasket 26 (disposed below) may be installed
between the cap plate 25 and the positive terminal 21 to insulate the cap plate 25 and
the positive terminal 21.
[0049] The positive terminal 21 may have a cylindrical shape. A nut 29 (that supports
the positive terminal 21 at an upper portion thereof) may be installed in the positive
terminal 21, and a screw thread for coupling the nut 29 may be formed on an outer
circumference of the positive terminal 21.
[0050] The positive terminal 21 may be electrically connected to the positive uncoated
region 11 a through a current collecting member 5 1 and a terminal flange (that supports
the positive terminal 21 and the current collecting member 5 1) may be formed at a
lower end of the positive terminal 2 1. Below the positive terminal 2 1, a lower
insulating member 41 may insulate the positive terminal 21 and the cap plate 25.
The negative terminal 22 may penetrate through the cap plate 25, and a frrst
gasket 24 (disposed above) and a second gasket 26 (disposed below) may be installed
between the cap plate 25 and the negative terminal 22 to insulate the cap plate 25 and
the negative terminal 2 1.
The negative terminal 22 may have a cylindrical shape. A nut 29 (that supports
the negative terminal 22 at an upper portion thereof) may be installed in the negative
terminal 22, and a screw thread for coupling the nut 29 may be formed on an outer
circumference of the negative terminal 22.
[0053] The negative terminal 22 is electrically connected to the negative uncoated
region 12a through a current collecting member 52 and a terminal flange (that supports
the negative terminal 22 and the current collecting member 52) may be formed at a
lower end of the negative terminal 22.
[0054] Below the negative terminal 22, a lower insulating member 42 may insulate the
negative terminal 22 and the cap plate 25.
[OOSS] As shown in FIG. 3, the negative electrode 12 may include the negative current
collector 121 and the negative active material layers 122 on surfaces of the negative
current collector 121. For example, the negative current collector 121 may include a
negative coated region 12b where active material is coated and a negative uncoated
region 12a £tee of active material.
[0056] The negative current collector 121 may be formed of, e.g., copper or aluminum.
The negative current collector 121 may have a plate shape that is elongated in one
direction. The negative active material layer 122 may include, e.g., Li4Ti5OI2o r a
carbon-based active material, a conductive agent, a binder, or the like. The negative
active material layer 122 may be coated on the negative current collector 12 1 and
attached by a lamination method.
The negative uncoated region 12a may be stretched by hammering using
vibrations. In an implementation, the negative uncoated region 12a may be stretched by
hammering, e.g.ssing ultrasonic vibrations. As a result, as shown in FIG. 4, an
average thickness of the negative current collector 121 in the negative uncoated region
12a may be smaller than that of the negative current collector 121 in the negative coated
region 12b. For example, the average thickness of the negative current collector 121 in
the negative uncoated region 12a may be about 80% to about 95% of that of the
negative current collector 121 in the negative coated region 12b.
As shown in FIG. 5, when the average thickness of the negative current collector
12 1 in the negative uncoated region 12a is smaller than that of the negative current
collector 121 in the negative coated region 12b, a stretching ratio of the negative current
collector 121 in the negative uncoated region 12a may be increased to be stretched more
by a small force. Therefore, in the process of pressing the negative current collector
12 1 in the negative coated region 12b, the negative current collector 12 1 in the negative
uncoated region 12a may also be naturally stretched, thereby preventing the negative
electrode 12 fiom being curved.
FIG. 6A illustrates a graph showing an X-ray diEaction profile or pattern of a
negative uncoated region according to an embodiment. FIG. 6B illustrates a graph
showing an X-ray diffraction profile or pattern of a negative coated region according to
an embodiment.
[0060] FIGS. 6A and 6B show results of analyzing crystals of the negative current
collector 12 1 in the negative uncoated region 12a and the negative coated region 12b by
using X-ray diffraction after hammering the copper negative current collector 121 in the
negative uncoated region 12a by using ultrasonic vibrations.
[0062] In the present embodiment, the negative current collector 121 made of copper is
described as an example, and each FWHM (full width at half maximum) of peaks of
directions 1 11 and 002 is exemplified. However, the embodiments are not limited
thereto, and the FWHM of the peak of direction 11 1 may correspond to the FWHM of
the maximum peak of an electrode substrate and the FWHM of the peak of direction
002 may correspond to the FWHM of the second largest peak of the electrode substrate.
[Table 11
I Samule 3 I 1.23 I 1.79 I
I 11 1/I 002
Sample 1
Samule 2
Coated region
1.28
1.32
I Average I 1.28
Hammering-processed uncoated region
1.90
1.87
1.85
Table 1 shows a comparison between the FWHM of the peaks of direction 11 1
and the FWHM of the peaks of direction 002, shown in FIGS. 6A and 6B of the
negative current collector 121 in the negative uncoated region 12a and the negative
coated region 12b.
[0065] In Table 1, the hammering (using ultrasonic vibrations) was performed with a
frequency of 10 kHz at a pressure of 0.6 m a and a moving speed of the negative
current collector 121 was 5 dmin.
As shown in Table 1, an average ratio of the FWHM of the peak of direction
1 1 1 to the FWHM of the peak of direction 002 of the negative current collector 121 in
the negative uncoated region 12a according to the present embodiment was 1.85. An
- 14-
average ratio of the FWHM of the peak of direction 1 1 1 to the FWHM.of the peak of
direction 002 of the negative current collector 121 in the negative coated region 12b
was 1.28.
[0067] For example, both the FWHM's of the peaks of direction 1 1 1 and direction 002
were reduced due to the hammering using ultrasonic vibrations, but the FWHM of the
peak of direction 002 was reduced to a greater degree.
[0068] A ratio of I 11 111 002 (i.e., a ratio of the FWHM of the peakof direction 1 11 to
the FWHM of the peak of direction 002 of the negative current collector 121 in the
negative uncoated region 12a) may be about 1.4 to about 2.0. Maintaining the ratio of I
11 111 002 at about 1.4 or greater may help ensure that the change in crystal orientation
is sufficient, thereby preventing curving of the stretched negative uncoated region.
Maintaining the ratio of I 11 1/I 002 at about 2.0 or less may help ensure that the change
in crystal orientation is not too large, thereby preventing tearing of the negative
uncoated region.
[0069] Further, in comparing the FWHM ratios of the peaks of the negative current
collector 121 in the negative uncoated region 12a and the negative coated region 12b,
the ratio of 1 11 1/I 002 of the negative current collector 121 in the negative uncoated
region 12a may be lager than the ratio of I 11 111 002 in the negative coated region 12b.
When the ratio of the FWHM of the maximum peak: the FWHM of the second largest
peak of the negative current collector 121 in the negative uncoated region 12a is
increased (e.g., due to a change in crystal orientation), a length of the negative current
collector 121 in the negative uncoated region 12a may be increased, and the stretching
ratio is increased in a lengthwise direction of the negative current collector 121 in the
negative uncoated region 12a, thereby preventing the negative electrode fiom being
curved.
The ratio of I 1 1 111 002 of the negative current collector 121 in the negative
uncoated region 12a may be about 1.3 to about 1.6 times the ratio of I 1 11h 002 of the
negative current collector 121 in the negative coated region 12b.
[007 11 One method of increasing the stretching ratio of the negative current collector in
the uncoated region is to perform an annealing process. If the annealing is performed to
increase the stretching ratio, an oxide film may be formed on a surface of the negative
current collector in the uncoated region during heat treatment, leading to an undesirable
increase in resistance. For example, in the case of copper, an oxide film may be easily
formed due to some moisture or a rise in temperature under a general atmospheric
condition. Thus, the oxide film formed as above may be eluted inside the rechargeable
battery and thus may serve as a by-product during charging and discharging, which may
adversely affect a cycle-life, safety, and the like. Further, in the annealing, when a
substrate, e.g., an electrolytic copper foil with little internal stress, is used, a physical
property thereof may not be changed and thus it may be difficult to prevent an electrode
fiom being curved.
LO0721 Another method of stretching the negative current collector in the uncoated
region is to roll using a roller. However, when rolling with the roller, a crack may be
generated due to a stretching deviation on a boundary surface between a rolled portion
and a non-rolled portion. As a result, a current path may be disconnected. Furthermore,
when rolling even the coated region, a mixture density may be changed and thus the
active material may be eliminated. In addition, an ultra high pressure hydraulic cylinder
may be required for rolling, and it may be difficult to control a pressure of the hydraulic
cylinder.
According to the embodiments, when the hammering using ultrasonic vibrations
is applied, the negative current collector in the uncoated region may be intermittently
stretched by minute impact, thereby preventing the undesirable generation of a crack.
In addition, the negative current collector in the uncoated region may be stretched and
simultaneously, a stretching ratio of the negative current collector in the uncoated
region may be increased, thereby preventing the electrode fiom being curved.
[0074] Referring to FIG. 7, the positive electrode 11 according to an embodiment may
include the positive current collector 112 and the positive active material layer 113 on
surfaces of the positive current collector 112. For example, the positive current
collector 112 may include the positive coated region 1 lb (where an active material is
coated) and the positive uncoated region 1 la (free of active material).
The positive current collector 112 may be formed of, e.g., aluminum, and may
have a plate shape that is elongated in one direction. The positive active material layer
may include, e.g., LiCoO2, LiMnO2, LiNiO2, or the like, a conductive agent, a binder, or
the like. The positive active material layer 113 may be coated on the positive current
collector 112 or may be attached by a lamination method.
The positive current collector 1 12 in the positive uncoated region 1 la may be
stretched by hammering using ultrasonic vibrations. As a result, an average thickness
of the positive current collector 1 12 in the positive uncoated region 1 la may be smaller
than an average thickness of the.positive current collector 112 in the positive coated
region 1 1 b.
[0077] A thickness of the positive current collector 112 in the positive uncoated region
1 la may be about 80% to about 95% of the thickness of the positive current collector
1 12 in the positive electrode coating ratio 1 lb.
[0078] As the crystal orientation of the positive uncoated region 1 la is changed by the
hammering using ultrasonic vibration, an FWHM of a maximum peak and an FWHM of
a second largest peak (according to X-ray diffraction analysis) of the positive current
collector 1 12 in the positive uncoated region 1 la may be smaller than an FWHM of a
maximum peak and an FWHM of a second largest peak (according to the X-ray
diffraction analysis) of the positive current collector 112 in the positive coated region
1 lb.
[0079] For example, a ratio of (FWHM of maximum peak)/(FWHM of second largest
peak) of the positive current collector 1 12 in the positive uncoated region 1 la may be
larger than a ratio of (FWHM of maximum peak):( FWHM of second largest peak) of
the positive current collector 112 in the positive coated region 1 lb. The ratio of
(FWHM of maximum peak)/( FWHM of second largest peak ) of the positive current
collector 1 12 in the positive uncoated region 1 la may be about 1.3 to about 1.6 times
the ratio of (FWHM of maximum peak):( FWHM of second largest peak) of the positive
current collector 112 in the positive coated region 1 lb due to hammering using
ultrasonic vibrations.
[OOSO] When the ratio of the FWHM of the maximum peak and the FWHM of the
second largest peak of the positive current collector 112 in the positive uncoated region
1 la is increased (e.g., due to a change in crystal orientation), a length of the positive
uncoated region 1 la may be increased, and a stretching ratio may be increased in a
lengthwise direction of the positive uncoated region 1 la, thereby helping to prevent the
negative electrode fiom being cunred.
[008 11 In an implementation, in the positive current collector 112 in the positive
uncoated region 1 la, the ratio of (FWHM of maximum peak )/( FWHM of second
largest peak), e.g., a ratio of the FWHM of the maximum peak and the FWHM of the
second largest peak of the positive current collector 112 in the positive uncoated region
1 la, may be about 1.4 to about 2.0.
[0082] As described above, when the positive current collector 112 in the positive
uncoated region is hammered using ultrasonic vibrations, the crystal orientation of the
positive current collector 112 in the positive uncoated region may be changed, thereby
helping to prevent the positive electrode from being curved in the process of rolling or
pressing the positive coated region.
[0083] FIG. 8 illustrates a diagram showing a fabricating method of an electrode
according to an embodiment.
[0084] In FIG. 8, a positive electrode is described as an example, but the embodiments
are not limited thereto, and a negative electrode may fabricated by the same method.
[0085] A fabrication method of a positive electrode according to an embodiment may
include a step of forming a positive active material layer 11 3 on a positive current
collector 1 12, a step of vibration-hammering a preliminary positive uncoated region
(fiee of the positive active material layer 113) to form a positive uncoated region 1 1 a,
and a step of pressing a coated region (where the positive active material layer 113 is
coated).
[0086] In the step of forming the positive active material layer 113, the positive active
material layer 113 may be formed on a part of the positive current collector 112 by
using a coater 7 1 discharging an active material. The positive active material layer 113
may be simultaneously formed on both surfaces of the positive current collector 112.
Or as shown in FIG. 8, after the positive active material layer 113 is formed on one
surface of the positive current collector 112, the positive active material layer 113 may
be sequentially formed on the other surface.
In the vibration-hammering step, the preliminary positive uncoated region may
be hammered by using an ultrasonic vibration hammering device 60 to form the positive
uncoated region 1 la. The ultrasonic vibration hammering device 60 may include an
anvil 61 having a cylindrical roller structure, a horn 62 hammering the preliminary
positive uncoated region, that moves on the anvil 61, using ultrasonic vibrations, and an
ultrasonic vibration generator 63 applying ultrasonic vibrations to the horn 62.
The preliminary positive uncoated region may move on the rotating anvil 6 1 and
the horn 62 may vibration-hammer the preliminary positive uncoated region vertically
while vibrating at an ultrasonic wave frequency. When the positive current collector
1 12 moves while being hammered, hammering using ultrasonic vibrations may be
continuously performed and in this process, the positive uncoated region 1 la may be
formed and stretched. ,A
In an implementation, the ultrasonic vibrations may have a frequency of about 8
to about 12 kHz. In an implementation, the horn 62 may strike the preliminary
uncoated region with a pressure of about 0.4 to about 0.8 MPa. In an implementation,
the preliminary uncoated region may be passed along the anvil 61 at a speed of about 3
mlmin to about 7 mlmin.
[0090] In the pressing step, the positive coated region 1 lb may be pressed using
pressing rollers 73 and 74 and during the pressing process, the positive coated region
1 lb may be stretched. As the positive coated region 1 lb is stretched, the positive
uncoated region 1 la may be stretched together therewith. The ultrasonic vibration
hammering processed positive uncoated region 1 la may be easily stretched even by a
small force. Thus, the positive electrode may be prevented from being curved.-
[009 11 FIG. 9 illustrates a diagram showing a fabricating method of an electrode
according to an embodiment.
[0092] Referring to FIG. 9, a fabricating method of an electrode according to an
embodiment will be described. In the present embodiment, an electrode 15 may refer to
a positive electrode or a negative electrode that are applied to a rechargeable battery.
[0093] The fabricating method of the electrode 15 according to the present embodiment
may include a step of forming an active material layer 152 on a current collector 15 1, a
step of drying an electrode where the active material layer 152 is formed, a step of
pressing a coated region (where the active material layer 152 is coated), and a step of
vibration-hammering a preliminary uncoated region (fiee of the active material layer
152) to form the uncoated region.
In the step of forming the active material layer 152, the active material layer 152
may be formed on a part of the current collector 15 1 by using a coater discharging an
active material. The active material layer 152 may be simultaneously formed on both
surfaces of the current collector 15 1. Or as shown in FIG. 9, after the active material
layer 152 is formed on one surface of the current collector 15 1, the active material layer
152 may be sequentially formed on the other surface.
[0095] In the drying step, the electrode 15 may be moved into a drying path 75 to dry a
volatile liquid remaining inside the active material layer.
[0096] In the pressing step, the coated region may be pressed using pressing rollers 73
and 74 and during the pressing process, the coated region may be stretched. As the
coated region is stretched, tensile stress may be applied to the preliminary uncoated
region.
In the vibration-hammering step, after the pressing step, the preliminary
uncoated region may be hammered using an ultrasonic vibration hammering device 60.
The ultrasonic vibration hammering device 60 may include an anvil 6 1 having a
cylindrical roller structure, a horn 62 hammering the preliminary uncoated region, that
moves on the anvil 61, using ultrasonic vibrations, and an ultrasonic vibration generator
63 applying ultrasonic vibrations to the horn 62.
The preliminary uncoated region may move on the rotating anvil 6 1, and the
horn 62 may vibration-hammer the preliminary uncoated region vertically while
vibrating at an ultrasonic wave frequency. When the current collector 112 moves while
being hammered, hammering using ultrasonic vibrations may be continuously
performed. In this process, the preliminary uncoated region may be stretched to form
the uncoated region and thus tensile stress applied to the uncoated region may be
removed.
In an implementation, the ultrasonic vibrations may have a eequency of about 8
to about 12 kHz. In an implementation, the horn 62 may strike the preliminary
uncoated region with a pressure of about 0.4 to about 0.8 m a . In an implementation,
the preliminary uncoated region may be passed along the anvil 61 at a speed of about 3
dmin to about 7 dmin.
[00 1 001 In the present embodiment, the vibration-hammering step may be performed
after the pressing step, but the embodiments are not limited thereto. For example, the
vibration-hammering step may be performed together with the pressing step.
[OOlOl] By way of summation and review, after being coated with the active material,
the positive electrode and the negative electrode may be pressed flatly by a press or the
like. The coated region may be pressed by the press to be stretched, but the uncoated
region may hardly receive any pressing force and thus may not be stretched. As
described above, when stretching ratios of the coated region and the uncoated region are
different fiom each other, the electrode may warp. If the electrode warps, an error may
occur in the process of winding the electrode (that is elongated in one direction),
leading to a reduction in productivity and charging and discharging efficiency.
[00 1021 The embodiments provide a rechargeable dattery including an electrode in
which undesirable curvature thereof is reduced andlor prevented.
[00 1031 According to an embodiment, the current collector in the uncoated region may
be vibration-hammered to be stretched, and a stretching ratio of the current collector in
the uncoated region may be increased, thereby preventing the electrode fiom warping.
[00 1041 Example embodiments have been disclosed herein, and although specific terms
are employed, they are used and are to be interpreted in a generic and descriptive sense
only and not for purpose of limitation. In some instances, as would be apparent to one
of ordinary skill in the art as of the filing of the present application, features,
characteristics, andlor elements described in connection with a particular embodiment
may be used singly or in combination with features, characteristics, andlor elements
described in connection with other embodiments unless otherwise specifically indicated.
Accordingly, it will be understood by those of skill in the art that various changes in
form and details may be made without departing from the spirit and scope of the present
invention as set forth in the following claims.

WE CLAIM:
1. A rechargeable battery, comprising:
an electrode assembly, the electrode assembly including:
a first electrode,
a second electrode, and
a separator between the first electrode and the second electrode; and
a case accommodating the electrode assembly,
wherein:
each of the first and second electrodes includes a coated region having an active
material layer on a current collector and an uncoated region fi"ee of the active material
layer, and
in at least one electrode of the first and second electrodes, the current collector is
characterized by an x-ray diffraction pattern in which a ratio of an FWHM of a largest
peak:an FWHM of a second largest peak of the current collector in the uncoated region
is greater than a ratio of an FWHM of a largest peak:an FWHM of a second largest peak
of the current collector in the coated region.
2. The rechargeable battery as claimed in claim 1, wherein the ratio of the
FWHM of the largest peak:the FWHM of the second largest peak of the current
collector in the uncoated region is about 1.3 to about 1.6 times the ratio of the FWHM
of the largest peak:the FWHM of the second largest peak of the current collector in the
coated region.
- 25 -
3. The rechargeable battery as clauned in claim 1, wherein, in the at least
one electrode, the x-ray diffraction pattern of the current collector has a ratio of an
FWHM of a largest peak:an FWHM of a second largest peak of about 1.4 to about 2.0
in the uncoated region.
4. The rechargeable battery as claimed in claim 1, wherein the current
collector of the at least one electrode has an average thickness in the uncoated region
smaller than an average thickness thereof in the coated region.
5. The rechargeable battery as claimed in claim 4, wherein, in the at least
one electrode, the average thickness of the current collector in the uncoated region is
about 80 to about 95 % of the average thickness of the current collector in the coated
region.
6. The rechargeable battery as claimed in claim 1, wherein the current
collector of each of the first electrode and the second electrode is characterized by the xray
diffraction pattern in which a ratio of an FWHM of a largest peak:an FWHM of a
second largest peak of the current collector in the uncoated region is greater than a ratio
of an FWHM of a largest peak:an FWHM of a second largest peak of the current
collector in the coated region.
-26-
7. The rechargeable battery as claraied in claim 1, wherein each uncoated
region of each of the electrodes extends along a side end, respectively, of the current
collector.
8. A method of manufacturing a rechargeable battery, the method
comprising preparing an electrode such that preparing the electrode includes:
coating an active material on a portion of a current collector to form a coated
region and a preliminary uncoated region, the preliminary uncoated region extending
along one side end of the current collector and being free of the active material; and
vibration hammering the current collector in the prelimmary uncoated region to
form an uncoated region such that the current collector is characterized by an x-ray
diffraction pattern in which a ratio of an FWHM of a largest peak:an FWHM of a
second largest peak of the current collector in the uncoated region is greater than a ratio
of an FWHM of a largest peak:an FWHM of a second largest peak of the current
collector in the coated region.
9. ThemethodasclaimedinclaimS, wherein the ratio of the FWHM of the
largest peak:the FWHM of the second largest peak of the current collector in the
uncoated region is about 1.3 to about 1.6 times the ratio of the FWHM of the largest
peakrthe FWHM of the second largest peak of the current collector in the coated region.
-26-
7. The rechargeable battery as claimed in claim 1, wherein each uncoated
region of each of the electrodes extends along a side end, respectively, of the current
collector.
8. A method of manufacturing a rechargeable battery, the method
comprising preparing an electrode such that preparing the electrode includes:
coating an active material on a portion of a current collector to form a coated
region and a preliminary uncoated region, the preliminary uncoated region extending
along one side end of the current collector and being free of the active material; and
vibration hammering the current collector in the preliminary uncoated region to
form an uncoated region such that the current collector is characterized by an x-ray
diffraction pattern in which a ratio of an F WHM of a largest peakran F WHM of a
second largest peak of the current collector in the uncoated region is greater than a ratio
of an FWHM of a largest peakran FWHM of a second largest peak of the current
collector in the coated region.
9. The method as claimed in claim 8, wherein the ratio of the FWHM of the
largest peakrthe FWHM of the second largest peak of the current collector in the
uncoated region is about 1.3 to about 1.6 times the ratio of the FWHM of the largest
peak:the FWHM of the second largest peak of the current collector in the coated region.
-27-
10. The method as claimed in claim 8, wherein the x-ray dififraction pattern
of the current collector has a ratio of an FWHM of a largest peak:an FWHM of a second
largest peak of about 1.4 to about 2.0 in the uncoated region.
11. The method as claimed in claim 8, wherein the current collector has an
average thickness in the uncoated region smaller than an average thickness thereof in
the coated region.
12. The method as claimed in claim 11, wherein the average thickness of the
current collector in the uncoated region is about 80 to about 95 % of the average
thickness of the current collector in the coated region.
13. The method as claimed in claim 8, wherein the vibration hammering
includes ultrasonic vibration hammering.
14. The method as claimed in claim 13, wherein the ultrasonic vibration
hammering includes:
passing the preliminary uncoated region along an anvil,
generating ultrasonic vibrations with an ultrasonic vibration generator, and
striking the preliminary uncoated region with a horn that vibrates in response to
the ultrasonic vibrations of the ultrasonic vibration generator.
- I S IS.
The method as claimed in claim 14, wherein:
the anvil has a cylmdrical roller structure, and
passing the preliminary uncoated region along the anvil includes rolling the
prelimmary uncoated region along the cylindrical roller.
16. The method as claimed in claim 14, wherein:
the ultrasonic vibrations have a frequency of about 8 to about 12 kHz,
the horn strikes the preliminary uncoated region with a pressure of about 0.4 to
about 0.8 MPa, and
the preliminary uncoated region is passed along the anvil at a speed of about 3
m/min to about 7 m/min.
17. The method as claimed in claim 8, further comprising pressing the
coated region between pressing rollers.
18. The method as claimed in claim 17, wherein vibration hammering the
current collector in the preliminary uncoated region occurs prior to pressing the coated
region.
19. The method as claimed in claim 17, wherein pressing the coated region
occurs prior to vibration hammering the current collector in the preliminary uncoated
region.
20. The method as claimed in claim 8, further comprising drying the active
material.