KR20240071107A - Electrode assembly and secondary battery including the same - Google Patents

Abstract

The present invention includes a zigzag-shaped separator and a cathode and an anode stacked in order between the separators and including a cathode tab and an anode tab, respectively, wherein the anode includes an internal anode stacked between the separators, the separator, and the cathode. and an external anode stacked on the outermost side in the stacking direction of the internal anode stack, wherein the external anode includes an insulating member that prevents the negative electrode tab from contacting one surface of the external anode. It's about.

Description

Electrode assembly and secondary battery including the same {ELECTRODE ASSEMBLY AND SECONDARY BATTERY INCLUDING THE SAME}

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

In general, secondary batteries refer to batteries that can be charged and discharged, unlike primary batteries that cannot be recharged. These secondary batteries are widely used in the field of advanced electronic devices such as phones, laptop computers, and camcorders.

The stability of secondary batteries can be ensured through a stability test that measures internal short circuits by compressing one side with a press.

Depending on the shape of the battery case, secondary batteries include cylindrical batteries and square batteries in which the electrode assembly is built into a cylindrical or square metal can, and pouch case-type batteries in which the electrode assembly is built in a pouch case-type case of aluminum laminate sheet. are classified.

Pouch case type batteries include stacked type and stacked/folded type electrode assemblies. Pouch-type batteries, which have a stacked or stacked/folded electrode assembly built into a pouch-type battery case of aluminum laminated sheets, are attracting a lot of attention due to their low manufacturing cost, low weight, and easy shape deformation. Usage is gradually increasing.

On the other hand, the stacked electrode assembly or stacked/folded electrode assembly forms a structure in which a separator is interposed between the anode electrode and the cathode electrode with an electrode tab protruding on one side, and the electrode tab protrudes outward from this structure. A problem occurred where the negative electrode tab was folded and came into contact with the positive electrode current collector located on the outermost side, causing a short circuit.

Korean Publication No. 10-2015-0098445

Focusing on the problems of the prior art described above, the present invention seeks to provide an electrode assembly that prevents the negative electrode tab from contacting the positive electrode and a secondary battery including the same.

One embodiment of the present invention includes a zigzag-shaped separator and a cathode and an anode stacked in order between the separators and including a cathode tab and an anode tab, respectively, and the anode includes an internal anode stacked between the separators and the anode. It includes an external anode stacked on the outermost side in the stacking direction of the separator, the cathode, and the internal anode, and the external anode includes an insulating member that prevents the cathode tab from contacting one surface of the external anode. A phosphorus electrode assembly is provided.

One embodiment of the present invention provides an electrode assembly wherein the insulating member covers a portion of the anode tab and includes a first insulating member and a second insulating member respectively covering surfaces opposing each other on both sides of the external anode. do.

One embodiment of the present invention provides an electrode assembly in which the external positive electrode includes a positive electrode current collector and a positive electrode active material layer provided on one surface of the positive electrode current collector.

One embodiment of the present invention provides an electrode assembly in which the first insulating member is positioned to cover a portion of the positive electrode active material layer and the positive electrode tab.

One embodiment of the present invention provides an electrode assembly in which the second insulating member is positioned to cover a portion of the positive electrode tab on a surface opposite to the surface of the positive electrode current collector provided with the positive electrode active material layer.

One embodiment of the present invention provides an electrode assembly in which one end of the first insulating member and the second insulating member is adhered.

One embodiment of the present invention provides an electrode assembly in which the insulating member includes an insulating tape.

One embodiment of the present invention provides an electrode assembly in which the insulating member covers 20% to 80% of the length of the positive electrode tab.

One embodiment of the present invention provides an electrode assembly in which the insulating member is provided to extend along an end of the external anode where the anode tab is located.

One embodiment of the present invention provides an electrode assembly in which the length of the insulating member is equal to or longer than that of the positive electrode tab.

Another embodiment of the present invention provides a secondary battery including a case including the electrode assembly, a lower case including a receiving groove in which the electrode assembly is accommodated, and an upper case coupled to the lower case.

The electrode assembly and the secondary battery including the same according to an embodiment of the present invention can prevent contact with the negative electrode tab and internal short circuit by placing an insulating member on one side of the positive electrode located at the outermost part of the laminate.

1 is an exploded perspective view showing an electrode assembly according to an exemplary embodiment of the present invention.
Figure 2 is a cross-sectional view showing an electrode assembly according to an exemplary embodiment of the present invention.
Figure 3 is a front view and a rear view showing an external anode according to an exemplary embodiment of the present invention.
FIG. 4 is a cross-sectional view taken along line A-A' of FIG. 3.
Figure 5 is a cross-sectional view showing a secondary battery according to an exemplary embodiment of the present invention.

The detailed description of the present invention is intended to completely explain the present invention to those skilled in the art. Throughout the specification, when a part is said to “include” a certain component or is “characterized” by a certain structure and shape, this means excluding other components or excluding other structures and shapes unless specifically stated to the contrary. It does not mean that it does, but that it can include other components, structures, and shapes.

Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be presented and explained in detail in the detailed description. However, this is not intended to limit the content of the invention by examples, and should be understood to include all transformations, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. However, the drawings are for illustrating the present invention, and the scope of the present invention is not limited by the drawings.

FIG. 1 is a perspective view showing the electrode assembly 100 according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the electrode assembly 100 according to an exemplary embodiment of the present invention.

The electrode assembly 100 is a power generating element that includes an anode 110, a cathode 120, and a separator 130 located between the anode 110 and the cathode 120 and is capable of charging and discharging.

The electrode assembly 100 may include a stacking/folding structure in which an anode 110 and a cathode 120 are sequentially stacked on a separator 130 folded in a zigzag shape.

The positive electrode 110 may include a positive electrode current collector, a positive electrode active material portion, and a positive electrode tab. The positive electrode current collector is a thin metal plate with excellent conductivity and may include, for example, aluminum (Al) foil.

The positive electrode 110 is coated with a positive active material on one or both sides of a plate-shaped positive current collector, and the uncoated portion not coated with the positive active material can be cut into a positive electrode tab shape to form the positive electrode tab 111.

The positive electrode active material is lithium cobalt oxide with high operating voltage and excellent capacity characteristics, lithium nickel oxide with high reversible capacity and easy to implement large-capacity batteries, lithium nickel cobalt oxide in which part of nickel is replaced with cobalt, part of nickel in manganese, It may include lithium nickel cobalt metal oxide substituted with cobalt or aluminum, lithium manganese-based oxide with excellent thermal stability and low cost, and lithium iron phosphate with excellent stability.

The negative electrode 120 may include a negative electrode current collector, a negative electrode active material portion, and a negative electrode uncoated portion. The negative electrode current collector may include a thin metal plate with excellent conductivity, for example, copper (Cu) or nickel (Ni) foil.

The negative electrode 120 is formed by coating a negative electrode active material on one or both sides of a negative electrode current collector. The negative electrode active material portion is formed by coating or applying a negative electrode active material, and the negative electrode uncoated portion is cut into a negative electrode tab shape without coating or applying a negative electrode active material. A negative electrode tab 121 may be formed.

The negative electrode active material may be, for example, crystalline carbon, amorphous carbon, carbon composite, carbon material such as carbon fiber, lithium metal, or lithium alloy. At this time, the negative electrode active material may further include, for example, non-graphite SiO (silica) or SiC (silicon carbide) for high capacity design.

The positive electrode tab 111 and the negative electrode tab 121 transfer electrons collected in the current collector to an external circuit and may protrude in opposite directions or in the same direction from the electrode assembly of the stacked/folding structure.

The area of the cathode 120 included in the electrode assembly according to the present invention may be larger than that of the anode 110. Therefore, by setting the area of the cathode 120 to be larger than the area of the corresponding anode 110, lithium can be prevented from precipitating on the cathode 120.

The separator 130 prevents an internal short circuit that may occur when the anode 110 and the cathode 120 come into contact, and may include a porous material to facilitate the movement of ions between electrodes.

In one embodiment, the separator 130 may include a base layer made of a porous material. The base layer may include, for example, any one selected from the group consisting of polyethylene (PE), polystyrene (PS), polypropylene (PP), and a copolymer of polyethylene (PE) and polypropylene (PP). You can.

In another embodiment, the separator 130 may include a Safety Reinforced Separator (SRS) separator. That is, the separator 130 may include a base layer made of a porous material and a coating layer formed by applying a mixed slurry of inorganic particles and a binder polymer coated on the base layer. Preferably, the coating layer has a uniform pore structure formed by the pore structure included in the separator substrate itself, including ceramic particles, as well as the interstitial volume between the ceramic particles that are active layer components.

The coating layer may include ceramic particles containing at least one selected from the group consisting of alumina, silica, TiO ₂ , SiC, and MgAl ₂ O ₄ . By including such a coating layer, the safety of the electrode assembly can be enhanced. And, the coating layer may further include lithium salt.

The electrode assembly 100 according to the present invention may include an internal anode 110a and an external anode 110b.

In more detail, the electrode assembly 100 may have a structure in which an external anode 110b is stacked on the outermost layer of a stack 101 in which an anode and a cathode are stacked between separators 130 folded in a zigzag shape.

Here, the anode located between the separators 130 folded in a zigzag shape is the internal anode 110a, and the anode located at the top and bottom of the stack 101 is the external anode 110b. The internal positive electrode 110a may be coated with a positive active material on both sides of the positive electrode current collector, and the external positive electrode 110b may be coated with a positive active material on only one side of the positive current collector.

The external anode 110b may have the same area as the internal anode 110a or may be smaller.

The internal positive electrode tab 111a can be formed by cutting the positive electrode uncoated portion on one side of the internal positive electrode 110a that is not coated with the positive electrode active material. Accordingly, the internal positive electrode tab 111a may protrude outward from the area coated with the positive electrode active material.

The external positive electrode 110b includes a first surface 1 coated with the positive electrode active material and a second surface 2 not coated with the positive electrode active material. The external positive electrode 110b includes a first insulating member 112 located on the first side 1 and covering the positive electrode active material and the external positive electrode tab 111b, and a second insulating member 113 located on the second side 2. may include.

FIG. 3 is a front view and a rear view showing the external anode 110b according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line A-A' of FIG. 3.

The first insulating member 112 and the second insulating member 113 may each cover 20% to 80% of 100% of the width (Y) of the positive electrode tab. Preferably, the first insulating member 112 and the second insulating member 113 may each cover 30% to 70% of the width of the positive electrode tab, and more preferably may each cover 30% to 60% of the width of the positive electrode tab.

Alternatively, the first insulating member 112 and the second insulating member 113 may have a width of 5 mm or more and extend along the end of the external anode 110b where the external anode tab 111b is located. Preferably, the width of the first insulating member 112 and the second insulating member 113 may be 10 mm or more. Additionally, the length of the first insulating member 112 and the second insulating member 113 may be equal to or longer than the length of the external anode 110b. Here, the width (Y) refers to the length from the external positive electrode tab 111b in the direction of the positive electrode active material, and the length (X) refers to the length in the direction perpendicular to the width on the first side (1) or the second side (2). means.

When a high temperature is applied to the electrode assembly 100, the separator 130 may shrink, so that the width of the separator 130 may be wider than that of the anode 110 and the cathode 120. The first insulating member 112 prevents a short circuit from occurring due to direct contact between the external anode tab 111b and the cathode tab 121 when a high temperature is applied to the electrode assembly 100 and the separator 130 shrinks. You can.

The second insulating member 113 prevents the cathode tab 121 located on the cathode 120 located at the top and bottom of the laminate 101 from contacting the second surface 2 of the external anode 110b. can do.

Therefore, when the width of the first insulating member 112 satisfies the above range, it is possible to prevent the external positive electrode tab 111b and the negative electrode tab 121 included in the stack 101 from contacting each other. And, when the width of the second insulating member 113 satisfies the above range, the cathode tab 121 of the cathode 120 closest to the external anode 110b is moved to the second surface of the external anode 110b by external pressure. Even if it is folded in (2), it can be prevented from contacting the positive electrode current collector on the second side (2) of the external positive electrode (110b).

The first insulating member 112 and the second insulating member 113 are not particularly limited in shape as long as they have insulating properties, but may include an insulating tape.

In addition, the first insulating member 112 and the second insulating member 113 may include an insulating film and an adhesive layer (or adhesive layer) in which an adhesive material (or adhesive material) having insulating properties is applied to one surface of the insulating film. For example, the insulating film may be made of the same material as the separator 130.

The first insulating member 112 and the second insulating member 113 may include an insulating film, an adhesive layer (or adhesive layer), and an insulating sealing portion that can increase sealing between the electrode assembly 100 and the case 200. there is. At this time, the insulating sealing part may be located on one side of the insulating film where the adhesive layer is not located.

The adhesive layer of the first insulating member 112 may be fixed to the positive electrode active material of the external positive electrode 110b and the external positive electrode tab 111b, and the adhesive layer of the second insulating member 113 may be fixed to the second surface 2. . At this time, the adhesive layer of the first insulating member 112 and the second insulating member 113 may be exposed in an area where the external anode tab 111b is not located. In order to prevent the adhesive layers of the first insulating member 112 and the second insulating member 113 from being exposed, one end of the exposed portion of the first insulating member 112 and the second insulating member 113 may be bonded. .

In other words, the externally exposed ends of the first insulating member 112 and the second insulating member 113 may be located on the same line. Here, the same line means a line parallel to the direction in which the first insulating member 112, the second insulating member 113, and the external anode 110b are stacked.

The first insulating member 112 and the second insulating member 113 may have the same width, or the second insulating member 113 may have a narrower width. The first insulating member 112 is located on the first side 1 of the external positive electrode 110b and covers a portion of the positive electrode active material, and may need to be wider than the second insulating member 113 by the thickness of the positive electrode active material coated. .

Figure 5 is a cross-sectional view showing a secondary battery 1000 according to an exemplary embodiment of the present invention. The secondary battery 1000 includes an electrode assembly 100 and a case 200.

Case 200 includes a lower case 210 in which the electrode assembly 100 is accommodated, and an upper case 220 coupled to the lower case 210. The case 200 can be divided into an upper case 220 and a lower case 210 by bending the middle of the rectangular pouch membrane formed as one piece. In addition, a receiving groove 211 to accommodate the electrode assembly 100 is formed in the lower case 210 through press processing, etc., and a sealing portion 212 is formed for sealing with the upper case 220. The sealing portion 212 may be formed along one side and the remaining three sides where the upper case 220 and the lower case 210 are in integral contact. The case 200 includes two long sides where the upper case 220 and the lower case 210 face each other, and two short sides that face each other perpendicularly to the two long sides. Here, the first electrode lead 140 and the second electrode lead 150 of the electrode assembly 100 have the short side of the two short sides opposite the short side where the upper case 220 and the lower case 210 are connected. is withdrawn through At this time, insulating members (not shown) are attached to the first and second electrode leads 140 and 150, respectively, to prevent short circuits between the first and second electrode leads 140 and 150 and the case 200. can do.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

1000: Secondary battery
100: electrode assembly
1: side 1
2: Side 2
101: Laminate
110: anode
110a: internal anode
110b: external anode
111: positive tab
111a: Internal anode tab
111b: external anode tab
112: First insulating member
113: Second insulating member
120: cathode
121: cathode tab
130: Separator
140: first electrode lead
150: second electrode lead
200: case
210: lower case
211: Acceptance home
212: Sealing part
220: upper case

Claims (11)

Zigzag-shaped separator and
A cathode and an anode are stacked in order between the separators and each includes a cathode tab and an anode tab,
The anode includes an internal anode stacked between the separators and an external anode stacked on the outermost side in the stacking direction of the stack of the separator, the cathode, and the internal anode,
An electrode assembly wherein the external anode includes an insulating member that prevents the negative electrode tab from contacting one surface of the external anode. The electrode assembly according to claim 1, wherein the insulating member covers a portion of the anode tab and includes a first insulating member and a second insulating member that cover opposite surfaces of the external anode, respectively. The electrode assembly according to claim 2, wherein the external positive electrode includes a positive electrode current collector and a positive electrode active material layer provided on one surface of the positive electrode current collector. The electrode assembly of claim 3, wherein the first insulating member is positioned to cover a portion of the positive electrode active material layer and the positive electrode tab. The electrode assembly according to claim 3, wherein the second insulating member is positioned to cover a portion of the positive electrode tab on the surface opposite to the surface of the positive electrode current collector provided with the positive electrode active material layer. The electrode assembly according to claim 2, wherein one end of the first insulating member and the second insulating member is adhered. The electrode assembly according to claim 1, wherein the insulating member includes an insulating tape. The electrode assembly according to claim 1, wherein the insulating member covers 20% to 80% of the width of the positive electrode tab. The electrode assembly according to claim 1, wherein the insulating member is provided to extend along an end of the external anode where the anode tab is located. The electrode assembly according to claim 9, wherein the length of the insulating member is equal to or longer than that of the positive electrode tab. The electrode assembly of any one of claims 1 to 10, and
A case including a lower case including a receiving groove in which the electrode assembly is accommodated and an upper case coupled to the lower case.
A secondary battery containing.