Patent ID: 12230835

BEST MODE

Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention.

In addition, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. In the case in which one part is said to be connected to another part in the specification, not only may the one part be directly connected to the another part, but also, the one part may be indirectly connected to the another part via a further part. In addition, that a certain element is included does not mean that other elements are excluded, but means that such elements may be further included unless mentioned otherwise.

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

FIG.1is an exploded perspective view showing an electrode and a separator according to an embodiment of the present invention, andFIG.2is a vertical sectional view ofFIG.1.

Referring toFIGS.1and2, a separator110according to the present invention has a larger size than an electrode120and is configured to have a structure in which a separator substrate111and a coating part112are formed, the coating part112being formed on a surplus part, which is an outer periphery of the separator substrate111and is not in contact with the electrode120.

The electrode120includes an electrode body121coated with an active material and an electrode tab122protruding to one side. The coating part112is disposed to surround an outer periphery of the electrode body121, and a coating part is not formed on the separator substrate111overlapping the protruding electrode tab122.

Therefore, the separator on which the coating part112is formed may serve to guide a position of the electrode120, and may prevent positional tolerances in the stacking direction when a plurality of electrodes are stacked.

A thickness a1of the coating part112may be the same as a thickness a2of the electrode body121. Alternatively, when the coating part can serve as a position guide for the electrode, the thickness a1of the coating part112may be formed smaller than a thickness of the separator.

FIG.2shows a state in which a gap G between the electrode body121and the coating part112is formed to some extent. However, considering that the coating part serves to fix the position of the electrode, it is preferable that the gap G between the electrode body121and the coating part112is small. This applies equally to a gap between an electrode body and a coating part shown inFIGS.4,5,7and8below.

FIG.1shows a structure in which the coating part112is formed only on an upper surface of the separator substrate111. However, unlike this, the coating part may be formed on each of the upper and lower surfaces of the separator substrate111.

FIG.3is a perspective view showing a separator according to an embodiment of the present invention.

Referring toFIG.3, when compared with the separator110ofFIG.1, a separator130ofFIG.3is the same as the separator110ofFIG.1in that it is composed of a separator substrate131and a coating part132. However, unlike that the coating part112ofFIG.1is formed on the entire outer periphery of the electrode body121except for the electrode tab122, the coating part132is different in that it is formed only on surplus parts of outer peripheries of corner portions of the separator substrate131. Since the coating part132ofFIG.3is formed at portions corresponding to corners of the electrode body, the coating part132ofFIG.3has the advantage of minimizing the resistance of the separator itself while serving to fix the position of the electrode.

FIG.3shows a structure in which the coating part132is formed only on an upper surface of the separator substrate131. However, unlike this, the coating part may be formed on each of the upper and lower surfaces of the separator substrate131.

FIG.4is a vertical sectional view showing a first embodiment of an electrode assembly.

The sizes of positive electrode and negative electrode may be determined taking into account the capacity and cycle characteristics of a designed battery. However, considering that a negative electrode is formed relatively larger than a positive electrode when considering the irreversible property of lithium ions, the electrode assembly is configured to have a structure in which a negative electrode220is disposed on an upper surface of a separator210and a positive electrode230is disposed on a lower surface of the separator210.

However, as described above, the positive electrode may be designed to be larger than the negative electrode. Of course, the large electrode positioned on the upper surface of the separator may be the positive electrode and the electrode positioned on the lower surface may be the negative electrode.

The separator210is configured to have a structure in which a coating part212is formed on an upper surface of a separator substrate211and a coating part213is formed on a lower surface of the separator substrate211. Since the size of the negative electrode220is relatively larger than that of the positive electrode230, a surplus part of an outer periphery of a negative electrode surface217of the separator substrate211is narrower than a surplus part of an outer periphery of a positive electrode surface218of the separator substrate211. Therefore, a width c1of the coating part212formed not to overlap with the negative electrode220is formed to be narrower than a width c2of the coating part213formed not to overlap with the positive electrode230.

The coating part212and the coating part213may include colored dyes, and the coating part212and the coating part213formed on the same separator substrate211may include the dyes of the same color.

A thickness b1of the coating part212is equal to or smaller than a thickness b3of the negative electrode220, and a thickness b2of the coating part213is equal to or smaller than a thickness b4of the positive electrode230. Since the thickness b3of the negative electrode220and the thickness b4of the positive electrode230may be different, the thickness b1of the coating part212and the thickness b2of the coating part213may not be the same.

FIG.5is a vertical sectional view showing a second embodiment of an electrode assembly.

Referring toFIG.5, (a) ofFIG.5is an electrode assembly which is a C-type bi-cell configured to have a structure in which a negative electrode320, a separator310, a positive electrode330, a separator340, and a negative electrode320are sequentially stacked, and (b) ofFIG.5is an electrode assembly which is a A-type bi-cell configured to have a structure in which a positive electrode330, a separator350, a negative electrode320, a separator360, and a positive electrode330are sequentially stacked.

Since the size of the negative electrode320is larger than the size of the positive electrode330, a width of a coating part312formed on a surplus part of an outer periphery of a negative electrode surface that does not overlap with the negative electrode320in a separator substrate311is narrower than a width of a coating part313formed on a surplus part of an outer periphery of a positive electrode surface that does not overlap with the positive electrode330in the separator substrate311. The same applies to the separator340, so that a width of a coating part342formed on a surplus part of an outer periphery of a negative electrode surface that does not overlap with the negative electrode320in a separator substrate341is narrower than a width of a coating part343formed on a surplus part of an outer periphery of a positive electrode surface that does not overlap with the positive electrode330in the separator substrate341.

In the electrode assembly (b) ofFIG.5, since the size of the negative electrode320is larger than the size of the positive electrode330, a width of a coating part353formed on a surplus part of an outer periphery of a negative electrode surface that does not overlap with the negative electrode320in a separator substrate351is narrower than a width of a coating part352formed on a surplus part of an outer periphery of a positive electrode surface that does not overlap with the positive electrode330in the separator substrate351. The same applies to the separator360, so that a width of a coating part363formed on a surplus part of an outer periphery of a negative electrode surface that does not overlap with the negative electrode320in a separator substrate361is narrower than a width of a coating part362formed on a surplus part of an outer periphery of a positive electrode surface that does not overlap with the positive electrode330in the separator substrate361.

In addition, since the coating part may include a resin that is cured by ultraviolet irradiation or heat, a coating part cured by ultraviolet irradiation or heating may be formed after forming the coating part.

As described above, since the coating part in a cured state is formed in a separator surplus part, it is possible to prevent the separator from being folded. In addition, the cured coating part is disposed so as to overlap with an end of an electrode of the relatively large size, so that the coating part serves to support the electrode of the relatively large size not to be bent in the direction of an electrode of the relatively small size during the laminating process of the electrode assembly. In addition, when the electrode is out of position and overlaps with the cured coating part, a significant difference occurs in the thickness change of the electrode assembly, and thus, it is possible to easily detect a defective electrode assembly by a method of measuring the thickness.

Since the coating part313and the coating part343are formed on a periphery of the positive electrode330, widths of the coating part313and the coating part343are the same, and the sum of thicknesses of the coating part313and the coating part343may be equal to or less than a thickness of the positive electrode330.

Since the coating part312and the coating part342are formed on a periphery of the negative electrode320, widths of the coating part312and the coating part342are the same, and the sum of thicknesses of the coating part312and the coating part342may be equal to or less than a thickness of the negative electrode320.

In addition, the coating part313may not be formed on the separator310, and the coating part343of the separator340may be formed with the thickness of the positive electrode330. Alternatively, the coating part343may not be formed on the separator340, and the coating part313of the separator310may be formed with the thickness of the positive electrode330.

The coating parts312,313,342, and343may include colored dyes, and the coating parts formed on the same separator substrate may contain dyes of the same color. Thus, the colors of the coating part312and the coating part313may be the same as a first color, and the colors of the coating part342and the coating part343may be the same as a second color. However, the first color and the second color may be different colors.

Therefore, in a structure in which two separators are interposed between electrodes as shown inFIG.5, when any one of the two separators is arranged to be misaligned out of its original position, the coating part of the misaligned separator is exposed. Thus, it is possible to identify whether the electrode assembly is aligned or not through a vision test measured at the top of the electrode assembly.

The electrode assembly (b) ofFIG.5is configured to have a structure in which the positions of the positive electrode and the negative electrode are replaced in the electrode assembly (a), such that the separator360is applied to the position of separator310, and the separator350is applied to the position of separator340. The description of the separator substrate and the coating layer may be applied in the same manner as the description of the separator310and the separator340described above.

Meanwhile,FIG.6is a vertical sectional view showing a conventional electrode assembly. Referring toFIG.6, when an electrode assembly300is rolled in a direction of an arrow using a rolling roller301, there is a problem in that an end of the negative electrode320having a relatively large size is bent toward the positive electrode330having a relatively small size, due to the difference in size between the positive electrode330and the negative electrode320.

However, when using the electrode assembly including the separator in which the coating part is formed on the surplus part of the outer periphery as in the present invention, the coating part serves to support end protrusions of the electrodes according to the difference in size between the positive electrode and the negative electrode. Thus, it is possible to prevent the electrode from being deformed, such as bending of the end of the electrode, as the outer periphery of the electrode is supported by the coating part.

FIG.7is a vertical sectional view showing a third embodiment of an electrode assembly.

Referring toFIG.7, the electrode assembly (a) and the electrode assembly (b) have a form in which separators are added to outer surfaces of the outermost electrodes as compared with the electrode assembly (a) and the electrode assembly (b) ofFIG.5.

The added separators are configured to have a structure in which coating parts372,374,382, and384are formed only on surfaces facing the electrodes in separator substrates371,373,381, and383. The width of the coating parts372and374is the same as the width of the coating parts312and342, and the width of the coating parts382and384is the same as the width of the coating parts352and362.

Since the outer peripheries of the separators in the electrode assembly are formed to align in the stacking direction, it can be easily confirmed that a separator is misaligned. Since the coating parts are in close contact with each other to form a stack, it is possible to prevent folding of the separator during the manufacturing process, and to prevent deformation of the separator by repeated expansion and shrinkage of the electrode assembly during the use of the battery. In addition, the supporting and protecting roles of the electrode in the stacking direction of the electrode assembly can also be expected.

FIG.8is a schematic view showing a process of manufacturing an electrode assembly.

Referring toFIG.8, a separator substrate421and a separator substrate441are unwound and taken out. A negative electrode410, which has been cut, is attached to an upper surface of the separator substrate421while maintaining a constant distance, and a negative electrode430, which has been cut, is attached to a lower surface of the separator substrate441while maintaining a constant distance.

A coating part422is formed on an outer periphery of the negative electrode410by a resin sprayed from a coater491. On a lower surface of the separator substrate421corresponding to the coating part422based on the separator substrate421, a coating part423is formed on an outer periphery of a portion to which a positive electrode450, which has been cut, is to be attached.

The width of the coating part422and the coating part423may be formed in different sizes depending on the size of the positive electrode450and the negative electrode410. However, dyes included in the coating part422and the coating part423may be the same color, and the coating part422and the coating part423may include a material that is cured by ultraviolet irradiation or heating. Therefore, after passing through an ultraviolet light source492, a coating part422′ and a coating part423′ developing a color in a cured state are formed.

A coating part442is formed on an outer periphery of the negative electrode430by a resin sprayed from the coater491. On an upper surface of the separator substrate441corresponding to the coating part422based on the separator substrate441, a coating part443is formed on an outer periphery of a portion to which the positive electrode450, which has been cut, is to be attached.

The width of the coating part442and the coating part443may be formed in different sizes depending on the size of the negative electrode430and the positive electrode450. However, dyes included in the coating part442and the coating part443may be the same color, and the coating part442and the coating part443may include a material that is cured by ultraviolet irradiation or heating. Therefore, after passing through the ultraviolet light source492, a coating part442′ and a coating part443′ developing a color in a cured state are formed.

However, the color development of the coating part422′ and the coating part423′ may be formed differently from the color development of the coating part442′ and the coating part443′.

Since the cut positive electrode450is disposed between the separator420and the separator440, the cut positive electrode450is seated and attached to the inside of the coating part423′ and the coating part443′.

As such, since the negative electrode410, the separator420, the positive electrode450, the separator440, and the negative electrode430form a stacked structure, the negative electrode410, the separator420, the positive electrode450, the separator440, and the negative electrode430are laminated while passing through a pair of rolling rollers493. At this time, the coating parts423′ and443′ formed on the outer peripheries of the separators support ends of the negative electrodes410and430so as not to overlap with the positive electrode, and thus it is possible to prevent the ends of the negative electrodes410and430from being bent toward the positive electrode450.

Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible based on the above description without departing from the scope of the present invention.

DESCRIPTION OF REFERENCE SYMBOLS

110,130,210,310,340,350,360,420,440: Separators111,131,211,311,341,351,361,371,373,381,383,421,441: Separator substrates112,132,212,213,312,313,342,343,352,353,362,363,372,374,382,384,422,422′,423,423′,442,442′,443,443′: Coating parts120: Electrode121: Electrode body122: Electrode tab217: Negative electrode surface of separator substrate218: Positive electrode surface of separator substrate220,320,410,430: Negative electrodes230,330,450: Positive electrodes300: Electrode assembly301,493: Rolling rollers491: Coater492: Ultraviolet light sourcea1, b1, b2: Thicknesses of coating partsa2: Thickness of electrode bodyG: Gap between electrode body and coating partb3: Thickness of negative electrodeb4: Thickness of positive electrodec1, c2: Widths of coating parts

INDUSTRIAL APPLICABILITY

As described above, since the present invention has a coating film formed on a separator surplus part, the present invention provides an electrode assembly in which a separator is completely aligned in the vertical direction in a stacked state.

In addition, by arranging the separators such that the colors of the coating parts of the separators are alternately arranged, it is possible to solve a problem in which it is difficult to check the position of electrodes because the electrode having a relatively small area is obscured by the separator.

In addition, since the coating part including a curable resin is formed in the separator surplus part, it is easy to detect defects as the difference in the thickness change of the electrode assembly increases when an electrode deviates from the fixed position and overlaps with the cured coating part.

In addition, it is possible to prevent the electrode from being deformed in the rolling step of the electrode assembly due to a difference in size of neighboring electrodes by adding a coating part to a separator surplus part not in contact with the electrode.

Therefore, it is possible to prevent a problem in which an electrode mixture layer is separated from an electrode current collector due to deformation of an electrode, and it is possible to easily determine a defective electrode.