WO2018016773A1

WO2018016773A1 - Secondary battery

Info

Publication number: WO2018016773A1
Application number: PCT/KR2017/007109
Authority: WO
Inventors: 추성기; 김잔디; 어성화; 한다운
Original assignee: 삼성에스디아이 주식회사
Priority date: 2016-07-19
Filing date: 2017-07-04
Publication date: 2018-01-25
Also published as: KR102337569B1; KR20180009594A

Abstract

A secondary battery according to an embodiment of the present invention comprises: an electrode assembly which includes a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a first uncoated tab projecting from the first electrode and a second uncoated tab projecting from the second electrode; and a pouch case accommodating the electrode assembly and having a first joint portion and a second joint portion which are formed on an upper side and a lower side thereof, wherein the first uncoated tab projects in the direction of the first joint portion, the second uncoated tab projects in the direction of the second joint portion; the first uncoated tab and the second uncoated tab are spaced apart from each other by an inter-tab distance; and the first uncoated tab is spaced apart from one side of the electrode assembly by a first spaced-apart distance.

Description

Secondary battery

The present invention relates to a secondary battery.

A secondary battery is a battery that can be charged and discharged unlike a primary battery that is not rechargeable. Secondary batteries are widely used in portable electronic devices such as mobile phones, laptops, and camcorders, or widely used as power sources for driving motors of hybrid vehicles.

The secondary battery includes an electrode assembly including a positive electrode and a negative electrode and a separator interposed between the positive electrode and the negative electrode. The electrode assembly is accommodated in the case to perform charging and discharging, and the case is provided with terminals to supply or receive current. The case may be made of a metal plate or pouch.

When used as a power source for driving a motor of a hybrid vehicle or the like, a secondary battery having a high rate discharge characteristic having a high discharge capacity is required. To this end, an electrode assembly having a large charge or discharge capacity is used. In this case, an unflowed region in which no current flows in the electrode assembly may be generated. When a lot of these unflowed regions are generated, the discharge capacity may not be sufficient or the temperature may be concentrated at a specific portion of the electrode assembly due to the resistance generated as the current flows. Accordingly, there is a problem that heat shrinkage or damage of a specific portion occurs.

One aspect of the present invention is to provide a secondary battery capable of high rate discharge by reducing the non-flow region in which no current flows in the electrode assembly.

A secondary battery according to an exemplary embodiment of the present invention includes an electrode assembly including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, and a first plain tab protruding from the first electrode. And a pouch case accommodating the second plain tab and the electrode assembly protruding from the second electrode, wherein the first bonding portion and the second bonding portion are formed up and down, wherein the first plain tab protrudes in the direction of the first bonding portion. The second plain tab is protruded in the direction of the second joining portion, and the first plain tab and the second plain tab are spaced apart from each other by a tab distance, and the first plain tab is formed on one side of the electrode assembly. 1 spaced apart.

The tab distance may be a distance from one side of the first plain tab to a side of the second plain tab parallel to the short side direction of the electrode assembly and toward one side of the first plain tab.

The tab distance may be greater than the first separation distance.

The first separation distance may be greater than 1/2 of the thickness of the electrode assembly, and may be smaller than 1/20 of the width of the electrode assembly.

The aspect ratio of the width to the thickness of the electrode assembly may be greater than 10: 1.

Widths of the first plain tab and the second plain tab may be formed within 1/4 of the width of the electrode assembly.

A plurality of first plain tabs of the first electrode may protrude.

The thickness of the first plain tab and the second plain tab may be formed in a range of less than 3/4 of the thickness of the electrode assembly.

The secondary battery according to an embodiment of the present invention can perform a high rate discharge by reducing a non-flow region in which no current flows in the electrode assembly, and can prevent a phenomenon in which a temperature of a specific portion of the electrode assembly rises.

1 is a partially cutaway perspective view illustrating a rechargeable battery according to an exemplary embodiment of the present invention.

FIG. 2 is an exploded perspective view of the secondary battery shown in FIG. 1.

3 is a plan view of an electrode assembly applied to the secondary battery illustrated in FIG. 2.

4 is a cross-sectional view of an electrode assembly applied to the secondary battery illustrated in FIG. 2.

5 is a graph showing the high rate discharge characteristics of a secondary battery according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to the illustrated.

In addition, in various embodiments, components having the same configuration will be described only in the exemplary embodiment using the same reference numerals, and in other embodiments, only the components different from the exemplary embodiment will be described.

Throughout the specification, when a part is said to be "connected" with another part, it includes not only "directly connected" but also "indirectly connected" with another member therebetween. In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

1 is a partially cutaway perspective view of a rechargeable battery according to an exemplary embodiment of the present invention, and FIG. 2 is an exploded perspective view of the rechargeable battery illustrated in FIG. 1.

Referring to FIGS. 1 and 2, the secondary battery 100 according to the present exemplary embodiment includes a pouch case 30 in which the electrode assembly 10 and the electrode assembly 10 are embedded.

The electrode assembly 10 includes a separator 13 interposed between the first electrode 11 and the second electrode 12. The electrode assembly 10 may be formed by winding the first electrode 11, the second electrode 12, and the separator 13 together. As another example, the electrode assembly 10 may be formed by stacking the first electrode 11, the second electrode 12, and the separator 13.

The first electrode 11, the second electrode 12, and the separator 13 constituting the electrode assembly 10 are measured in a direction parallel to the winding axis around which the electrode assembly 10 is wound, and the length of the long side of the electrode assembly 10 is measured. When the length L of the assembly is measured in the direction orthogonal to the winding axis and the length of the short side direction of the electrode assembly 10 is the width W of the electrode assembly, the length L of the electrode assembly is the electrode. It may be formed larger than the width (W) of the assembly.

The thickness T of the electrode assembly may be measured in a direction orthogonal to both the length L of the electrode assembly and the width W of the electrode assembly, and may be smaller than the width W of the electrode assembly.

The first electrode 11 may be an anode or a cathode, which will be described using an anode as an example. In addition, the second electrode 12 may be formed of a cathode or an anode having a polarity opposite to that of the first electrode 11. Hereinafter, a case where the first electrode 11 is an anode and the second electrode is a cathode will be described as an example.

For example, the first electrode 11 may include a positive electrode current collector made of a strip-shaped metal thin plate and a positive electrode active material layer coated on one or both sides of the positive electrode current collector. The positive electrode current collector may be made of a metal material having excellent conductivity, such as an aluminum thin plate. The positive electrode active material layer may be formed of a material in which a binder, a conductive material, and the like are mixed with a lithium oxide.

The second electrode 12 may include, for example, a negative electrode current collector made of a strip metal foil and a negative electrode active material layer coated on one or both surfaces of the negative electrode current collector. The negative electrode current collector may be made of a metal material having excellent conductivity, for example, a copper thin plate. The negative electrode active material layer may be formed of a material in which a binder conductive material is mixed with a negative electrode active material such as a carbon material.

The separator 13 may be made of a porous material, and may be made of polyolefin such as polyethylene and polypropylene.

The pouch case 30 includes an accommodating part 31 accommodating the electrode assembly 10, an edge junction part 33 formed around the accommodating part 31, a first junction part 35, and a second junction part 36. can do.

The accommodating part 31 of the pouch case 30 accommodates the electrolyte together with the electrode assembly 10. The pouch case 30 may be formed of a film including an insulating layer, and may include a first plate 30a and a second plate 30b. The first plate 30a and the second plate 30b of the pouch case 30 may be joined by heat fusion at the edge junction 33, the first junction 35, and the second junction 36. The heat-sealed edge junction 33, the first junction 35, and the second junction 36 may prevent leakage of the electrolyte contained in the accommodation part 31 to the outside.

When the width of the edge junction 33 is large, the bonding force of the pouch case 30 may be increased, and the pouch case 30 may be more stably sealed to prevent leakage of the electrolyte.

The first junction 35 and the second junction 36 may be formed above and below the accommodation portion 31. The accommodating part 31 may be formed in the first plate 30a of the pouch case 30. Since the accommodating part 31 embeds the electrolyte together with the electrode assembly 10, it may be larger than the electrode assembly 10.

The first lead tab 21 and the second lead tab 22 are electrically connected to the first plain tab 11a of the first electrode 11 and the second plain tab 12a of the second electrode 12, respectively. It is connected.

Protective tapes

23 and 24 may be wound around the first lead tab 21 and the second lead tab 22 to prevent short circuits with the first junction 35 and the second junction 36. A large amount of current flowing through the first lead tab 21 and the second lead tab 22 prevents the first junction portion 35 and the second junction portion 36 from being generated such as thermal damage, and short-circuited by the current. To prevent this.

The first lead tab 21 protrudes out of the pouch case 30 through the first bonding part 35, and the second lead tab 22 moves out of the pouch case 30 through the second bonding part 36. It may protrude.

The first lead tab 21 may protrude outward from the first junction part 35 of the pouch case 30 and may be positioned to one side in the width (W) direction of the electrode assembly.

The first electrode 11 may be formed of a coating part coated with an active material on a current collector and one side of the coating part to be electrically connected to the first lead tab 21, and formed of a first non-coating tab 11 a not coated with the active material. Can be.

For example, the first non-coating tab 11a may be formed by forming one side of the current collector, which is not coated with the active material, into a plain portion, and then punching it with a punch or the like. In addition, the first electrode 11 may include a plurality of first plain tabs 11a.

Accordingly, the plurality of first non-coating tabs 11a may form a smooth current flow in the electrode assembly 10, thereby enabling stable high rate discharge.

The second lead tab 22 may protrude outward from the second junction portion 36 of the pouch case 30, and may be spaced apart from the first lead tab 21 in the width (W) direction of the electrode assembly to be offset from each other. can do.

That is, the first plain tab 11a connected to the first lead tab 21 and the second plain tab 12a connected to the second lead tab 22 are parallel to the length L direction of the electrode assembly. Protruding in opposite directions to each other, may be spaced apart from each other in the width (W) direction of the electrode assembly. Through this, the electrode area of the electrode assembly 10 formed between the first plain tab 11a and the second plain tab 12a can be secured to the maximum. The first plain tab 11a and the second plain tab 12a may be disposed in the diagonal direction on the electrode assembly 10.

The current in the electrode assembly 10 may flow from the second lead tab 22 to the first lead tab 21 in the length L direction of the electrode assembly. Therefore, in the secondary battery 100 according to the exemplary embodiment of the present invention, the flow path of the current is formed to be long, and thus the unflowed region of the current that may be generated in the electrode assembly 10 may be reduced.

The distance between the first plain tab 11a and the second lead tab 22 in the width W direction of the electrode assembly may be spaced apart by the tab distance D1. The tab distance D1 is parallel to the width W of the electrode assembly, which is a short side direction of the electrode assembly 10, from one side of the first plain tab 11a and is one of the first plain tabs 11a. It consists of a distance to one side of the second plain tab 12a facing the side. That is, the first plain tab and the second plain tab 12a are spaced apart from the side surface of the first plain tab 11a by the tab distance D1 (see FIG. 3) between the side surfaces of the second plain tab 12a. The tab distance D1 may be formed to be 1/2 or more of the width W of the electrode assembly. Accordingly, the electric current may flow in most regions of the electrode assembly 10 across the electrode assembly 10 diagonally.

Referring to FIG. 3, the electrode assembly 10 includes a first plain tab 11a and a second plain tab 12a that protrude upward and downward.

The first non-coating tab 11a may be spaced apart from one side of the electrode assembly 10 by the first separation distance D2. When the first plain tab 11a is positioned on one side of the electrode assembly 10, the risk of a short circuit that may be generated by contacting the first plain tab 11a and the pouch case 30 (see FIG. 2) may be prevented. can do. In addition, when a swelling phenomenon occurs due to an abnormal situation of the secondary battery 100 (refer to FIG. 1), the risk of a short circuit that may occur due to the contact between the first plain tab 11a and the pouch case 30 may be prevented. can do.

The width w11 of the first plain tab may be formed within a quarter of the width W of the electrode assembly. The larger the width w11 of the first plain tab is, the more advantageous the high rate discharge is. However, since the width w11 of the first non-coated tab in the limited width W of the electrode assembly is closely related to the inter-tap distance D1 and the first separation distance D2, there is a limitation in width. For example, the width w11 of the first plain tab may be 6 mm to 15 mm.

The width w12 of the second plain tab may be formed within a quarter of the width W of the electrode assembly, similar to the width w11 of the first plain tab, and may be equal to the length w11 of the width of the first plain tab. It may be formed differently.

However, since the discharge capacity of the electrode assembly 10 is large, it is preferable that the width w11 of the first plain tab and the width w12 of the second plain tab are the same length.

The second plain tab 12a is spaced apart from the other side of the electrode assembly 10. As mentioned above, the second plain tab 12a may be spaced apart from the other side of the electrode assembly 10 so that the second plain tab 12a is formed close to the other side of the electrode assembly 10. The risk of short circuits can be avoided.

Referring to FIG. 4, the first plain tab 11a may be spaced apart from one side of the electrode assembly 10 by a first separation distance D2. In addition, the first separation distance D2 may be formed within 1/20 of the electrode assembly width W, and may be larger than 1/2 of the thickness T of the electrode assembly.

In addition, the aspect ratio W / T of the width W to the thickness T of the electrode assembly may be greater than 10: 1.

In order to secure the maximum distance between the tabs D1 in the width W of the electrode assembly, the first separation distance D2 is preferably formed within 1/20 of the width W of the electrode assembly. Accordingly, the inter-tap distance D1 is greater than the first separation distance D2.

In addition, since the electrode assembly 10 is wound and pressed to form an elliptical cross section, one side of the electrode assembly 10 is formed to be curved. Therefore, the first separation distance D2 may be spaced apart from one side surface of the electrode assembly to be greater than 1/2 of the electrode assembly thickness T to prevent contact between the first plain tab and one end of the electrode assembly 10. have.

The thickness t11 of the first plain tab may be formed within 3/4 of the thickness T of the electrode assembly. As the thickness t11 of the first plain tab is thicker, currents emitted from the plurality of first plain tabs 11a can be supplied to the outside without loss. However, in consideration of the sealing and short-circuit problems of the pouch case 30, the thickness of the electrode assembly may be smaller than the thickness T. The thickness t11 of the first plain tab may be greater than or equal to 0.39 mm. In consideration of the high rate discharge, the thickness of the second plain tab may be the same as the thickness t11 of the first plain tab.

Referring to FIG. 5, a graph of measuring high rate discharge while increasing the inter-tap distance D1 (see FIG. 3) is disclosed. The graph shows 1C, 30C, and 50C by measuring the distance between taps (D1) and when the tap distance (D1) is formed.

The presence or absence of the tap-interval D1 at 1C discharge did not significantly affect the discharge efficiency. However, the discharge efficiency was good when the distance between taps D1 was large when discharging 30C, and high rate discharge was possible only when the distance between taps D1 was formed when discharging 50C.

Although the present invention has been described through the preferred embodiments as described above, the present invention is not limited thereto and various modifications and variations are possible without departing from the spirit and scope of the claims set out below. Those in the technical field to which they belong will easily understand.

(Explanation of the sign)

100: secondary battery 10: electrode assembly

11: first electrode 12: second electrode

11a: first plain tab 12a: second plain tab

13: Separator 21: first lead tap

22: second lead tab 23, 24: protective tape

30: pouch case

30a: first edition 30b: second edition

31: accommodating part 33: edge joint

35: first junction 36: second junction

D1: Distance between taps D2: First separation distance

W: electrode assembly width L: electrode assembly length

T: electrode assembly thickness t11: thickness of the first plain tab

w11: width of the first plain tab w12: width of the second plain tab

Claims

An electrode assembly including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode;

A first uncoated tab protruding from the first electrode and a second uncoated tab protruding from the second electrode; And

It includes a pouch case for receiving the electrode assembly, the first junction portion and the second junction portion formed up and down,

The first plain tab is protruded in the direction of the first junction, the second plain tab protrudes in the direction of the second junction, the first plain tab and the second plain tab is spaced apart from each other tab,

The first plain tab is spaced apart by a first separation distance from one side of the electrode assembly.
The method of claim 1,

The distance between the taps,

And a distance from one side of the first plain tab to one side of the second plain tab in parallel with a short side direction of the electrode assembly and toward one side of the first plain tab.
The method of claim 1,

The tab between the secondary battery is formed larger than the first separation distance.
The method of claim 1,

The first spacing,

The secondary battery is formed larger than 1/2 of the thickness of the electrode assembly, and smaller than 1/20 of the width in the short side direction of the electrode assembly.
The method of claim 4, wherein

The aspect ratio of the width to the thickness of the electrode assembly is greater than 10: 1 secondary battery.
The method of claim 4, wherein

The width of the first plain tab and the second plain tab,

Secondary battery formed within a quarter of the width of the electrode assembly.
The method of claim 1,

The secondary battery of the first electrode tab of the first electrode protrudes into a plurality.
The method of claim 1,

The thickness of the first plain tab and the second plain tab,

Secondary battery is formed in the range of less than 3/4 of the electrode assembly thickness.