KR20150060108A - Electrode Stack of Enhanced Rate Performance and Battery Comprising The Same - Google Patents

Abstract

The present invention relates to an electrode stack which is characterized by comprising one or more first separator interposed between electrodes having opposite polarities, and including one surface or both surfaces laminated on the electrode; one or more second separator interposed between electrodes having opposite polarities, and including one surface or both surfaces contacting with the electrode in non-contacting state; one or more first electrode including a first electrode material layer of high loading formed on a current current collector, and arranged on the outer side of the electrode current collector based on the second separator; and one or more second electrode including a second electrode material layer of relatively low loading compared with the first electrode material layer, and arranged on the inner side of the electrode current collector based on the second separator, and to a secondary battery comprising the same.

Description

[0001] The present invention relates to an electrode stack having improved rate characteristics and a battery including the electrode stack.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery capable of repeated charge and discharge and an electrode laminate constituting the same.

As information technology (IT) technology has developed remarkably, various portable information and communication devices have been spreading, so that the 21st century is being developed into a "ubiquitous society" capable of providing high quality information services regardless of time and place.

As a development base for such a ubiquitous society, a lithium secondary battery occupies an important position. The lithium secondary battery can be manufactured by incorporating an electrode stack body and an electrolyte in a housing portion of a battery case and thermally fusing an outer peripheral surface of the housing portion.

The electrode laminate includes a positive electrode plate, a separator plate, and a negative electrode plate of a predetermined size stacked in a stacked manner (one on top of the other) so that the separator plate is interposed between the positive electrode plate and the negative electrode plate, Rolled type (jelly-roll type) in which a separator sheet is wound in one direction, a predetermined number of stacked electrode assemblies are stacked on a separator sheet so that a separator sheet is interposed between a positive electrode sheet and a negative electrode sheet, A stack and folding type in which a predetermined number of electrode stacks are laminated by winding the separator sheet in a folded or unidirectional manner, and stacking and folding.

Fig. 1 is a schematic exploded perspective view of a conventional stack and folding type electrode laminate. The stacked and folded electrode stacked body 22 includes a positive electrode having a positive electrode tab 11, a negative electrode having a negative electrode tab 12, a stacked electrode stacked body laminated with a separator laminated, The stacked electrode laminate 21 and the separator sheet 30 are laminated by stacking the stacked electrode laminate members 21 by winding the separator sheet in one direction after arranging the stacked electrode assembly 21 on the separator sheet 30, There is a problem that the interfacial resistance at the interface is larger than the interfacial resistance at the interface between the electrode in the stacked electrode laminate 21 and the separator.

Disclosure of Invention Technical Problem [8] The present invention provides a secondary battery having improved rate characteristics and an electrode laminate constituting the secondary battery.

An electrode stack according to one non-limiting example of the present invention,

At least one first separator interposed between electrodes of opposite polarity and having one or both surfaces laminated with the electrodes;

One or more second separation membranes interposed between electrodes of mutually opposite polarities, one or both surfaces being in contact with the electrodes in an unmated state;

At least one first electrode having a first electrode layer of high loading formed on a current collector and disposed on an outer side (outer side) of the electrode stack body with respect to the second separator film; And

A second electrode material layer having a relatively low loading relative to the first electrode material layer is formed on the current collector and disposed on an inner side of the electrode stack body with respect to the second separator film At least one second electrode;

. ≪ / RTI >

The loading amount of the first electrode material of the high loading may be in the range of 101% to 200% of the loading amount of the low loading second electrode material, and more specifically may be in the range of 110% to 150%.

The first electrodes may be stacked with a first separator interposed between the anode and the cathode, and may be disposed outside the electrode stack with respect to the second separator. In a non-limiting example, the first electrodes may be stacked with the first separator interposed between the anode and the cathode, and disposed on the outermost side of the electrode stack with respect to the second separator.

The second electrodes may be stacked with a first separator interposed between the anode and the cathode, and may be disposed on the inner side of the electrode stack with respect to the second separator.

The first electrode material layer and the second electrode material layer, which are in contact with the second separation film in an unbonded state, may each include a first electrode active material having a high rate characteristic, and the first electrode material layer, The re-layer and the second electrode material layer may each include a second electrode active material having a low rate characteristic.

The first electrode active material and the second electrode active material may be a positive electrode active material or a negative electrode active material. In a non-limiting example, the first electrode active material and the second electrode active material may be a cathode active material.

Wherein the first electrode active material is at least one selected from the group consisting of a lithium transition metal oxide having a layered structure, a lithium transition metal oxide having a spinel structure, a lithium transition metal phosphate having an olivine structure, and a complex thereof, Or a compound in which a part of the transition metal is substituted with a dopant. At this time, the dopant is composed of Ni, Co, Mg, Ti, Sr, Zn, Ca, Cr, Si, Ga, Sn, P, V, Sb, Nb, Ta, Mo, W, Zr, And may be one or more kinds of elements selected from the group.

In one non-limiting example of the present invention, the dopant may substitute a portion of the transition metal in the range of 1 mol% to 5 mol%, based on the molar content of the total transition metal.

If the substitution amount of the dopant is less than 1 mol%, the desired rate characteristic improvement effect can not be obtained. If the substitution amount exceeds 5 mol%, the capacity may be lowered.

The second electrode active material is at least one selected from the group consisting of a lithium transition metal oxide having a layered structure, a lithium transition metal oxide having a spinel structure, a lithium transition metal phosphate having an olivine structure, and a complex thereof as a cathode active material , Or a compound in which a part of the transition metal is unsubstituted as a dopant.

In a non-limiting example, the first electrode active material may be an anode active material, an amorphous carbon-based material, lithium-titanium oxide, silicon and tin, or a mixture thereof.

In a non-limiting example, the second electrode active material may be a negative electrode active material, one selected from the group consisting of crystalline carbon-based materials, silicon and tin, or a mixture thereof or an alloy thereof.

The first electrode material layer and the second electrode material layer, which are in contact with the second separation film in an unbonded state, may each have a high porosity, and the first electrode material layer and the second electrode material layer, May have a relatively low porosity relative to the first electrode material layer and the second electrode material layer, respectively, having a high porosity.

In a non-limiting example, the electrode material layer having a low porosity may have a porosity ranging from 20% or more to 40% or less. In a non-limiting example, the electrode material layer having a high porosity may have a porosity ranging from more than 40% to less than 90%.

The electrode laminate may be a novel electrode laminate including one or more improved electrodes laminated on one or both surfaces of the first separator. At this time, one end and the other end of the anode, the first separator, the cathode, and the second separator may not cross each other. The above-described novel electrode laminate is characterized in that the positive electrode, the first separator, and the negative electrode each have a stacked and folded electrode stacked structure in which one end and the other end do not intersect with each other and the second separator surrounds a side surface of the electrode, It is distinguished from the sieve.

The improved electrode may be realized, for example, in such a structure that the first separation membrane is bonded to one surface of the anode or the cathode. Further, the first separator may be formed on both surfaces of the anode or on both surfaces of the cathode. The positive electrode, the first separator, and the negative electrode may be bonded to each other with the first separator interposed between the positive and negative electrodes. In this specification, an electrode group can be defined as an embodiment in which the anode, the first separator, and the cathode are bonded to each other with the first separator interposed between the anode and the cathode.

The polarities of the outermost electrodes of the electrode group may be equal to or different from each other. When the polarities of the outermost electrodes are the same, they can be referred to as S-type electrode groups, and when the polarities of the outermost electrode groups are different from each other, they can be referred to as D-type electrode groups. At least one of the outermost electrodes may be bonded to the first separators in a state interposed between the first separators.

In addition, the improved electrode may include any one of an anode and a cathode, and a first separator, and any one of an anode and a cathode may be bonded to the first separator. It can be defined as an electrode element. One of the positive electrode and the negative electrode may be interposed between the first separators, and either the positive electrode or the negative electrode may be bonded to the first separator.

The electrode laminate having the structure in which the separator is interposed between the positive electrode and the negative electrode as a combination of the electrode, the improved electrode, the first separator, the second separator, the electrode group, and the electrode element is included in the scope of the present invention.

The present invention can provide a secondary battery in which the novel electrode stack body and the stacked and folded electrode stack body are embedded in a battery case together with an electrolyte. The secondary battery may be a lithium secondary battery selected from the group consisting of a lithium ion polymer battery, a lithium ion battery, and a lithium polymer battery. The battery case may include a metal can or a laminate sheet including a metal layer and a resin layer It may be a pouch-type battery case. Known structures and components of a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery are incorporated herein.

Further, the present invention can provide a battery pack including the secondary battery and a device using the battery pack as a power source. The device may be an electric vehicle, a hybrid electric vehicle, a plug-in electric vehicle or a power storage device.

The electrode laminate according to a non-limiting example of the present invention differs from the conventional stack and folded electrode laminate in that the interface resistance at the laminated interface of the stacked electrode laminate and the separator sheet and the The difference in interfacial resistance between the electrode and the separator at the lamination interface can be minimized, so that it is possible to exhibit improved rate characteristics compared to the secondary battery including the conventional stack and folding type electrode laminate.

1 is a schematic exploded perspective view of a conventional stacked and folded electrode stack;
Figure 2 is a schematic cross-sectional view of an electrode stack according to a non-limiting example of the present invention;
3-7 are schematic cross-sectional views of various embodiments of the improved electrode.

Hereinafter, the present invention will be described in detail with reference to the drawings according to a non-limiting embodiment of the present invention, but the scope of the present invention is not limited thereto.

2 is a schematic cross-sectional view of an electrode stack according to a non-limiting example of the present invention.

2, electrode stack 400 includes stacked electrode stacks 310, stacked electrode stacks 320 and stacked electrode stacks 330, and stacked electrode stacks 330, And a second separator 140 that surrounds the sides of the stacked electrode stacks 310, 320, and 330. Specifically, the electrode stack body 400 includes an anode 110, a cathode 120, a first separator 130, and a second separator 140, and is disposed between the anode 110 and the cathode 120 The anode 110, the cathode 120, the first separator 130 and the second separator 140 are stacked such that the first separator 130 and the second separator 140 are interposed between the first separator 130 and the second separator 140, (110) and the side of the cathode (120) which is an electrode tap non-forming portion.

The stacked electrode assembly 310 includes a high loading anode 110 having a first electrode layer of high loading on both sides of the current collector, a first electrode layer of high loading on both sides of the current collector, The formed high loading cathode 120 and the first separator 130 are laminated and bonded in a state where the first separator 130 is interposed between the high loading anode 110 and the high loading cathode 120, And a structure in which the high loading cathode 120 is stacked as the outermost electrode.

The stacked electrode assembly 320 includes a low-loading anode 110 having a low-loading second electrode material layer formed on both sides of the current collector, a low-loading second electrode material layer on both sides of the current collector The low loading cathode 120 and the first separator 130 are laminated and bonded in a state where the first separator 130 is interposed between the low loading anode 110 and the low loading cathode 120, And the low loading anode 110 may be laminated as the outermost electrode.

The stacked electrode laminate 330 includes a high loading anode 110 having a first electrode layer of high loading on both surfaces of a current collector, a first electrode layer of high loading on both surfaces of the current collector, The formed high loading cathode 120 and the first separator 130 are laminated and bonded in a state where the first separator 130 is interposed between the high loading anode 110 and the high loading cathode 120, And a structure in which the high loading cathode 120 is stacked as the outermost electrode.

Referring to region A in FIG. 2, the high loading anode and the low loading cathode, which face each other with the second separator 140 therebetween, are in contact with the second separator 140 in an unbonded state. The high loading anode and the low loading anode facing each other with the second separator 140 therebetween are disposed on both surfaces of the cathode current collector 110E, respectively, with a cathode material layer 112 having a high porosity or a high- And an anode material layer 122 including a first anode active material having a high porosity or high rate property may be formed on both sides of the anode current collector 120E.

The anode material layer 112 faces the anode material layer 121 including the second anode active material having a low porosity or low rate characteristic with the first separator 130 interposed therebetween and the anode material layer 112, The separation membrane 130, and the anode material layer 121 are bonded to each other.

The anode material layer 122 faces the anode material layer 111 including the second cathode active material having a low porosity or low rate characteristic with the first separator 130 sandwiched therebetween and the anode material layer 122, The separator 130, and the anode material layer 111 are bonded to each other.

The positive electrode and the negative electrode facing each other with the second separator 140 therebetween are each formed with a positive electrode material layer containing a first positive electrode active material having a high porosity or high rate property on one surface of the positive electrode collector 110E, A cathode material layer including a second cathode active material having a low porosity or a low rate characteristic may be formed and an anode material layer including a first anode active material having a high porosity or high rate characteristic is formed on one surface of the anode current collector 120E And an anode material layer including a second anode active material having a low porosity or a low rate characteristic on the other surface.

The cathode material layer formed on the other surface of the anode current collector and the anode material layer formed on the other surface of the anode current collector may be respectively bonded to the first separator film.

The improved electrode having a structure in which one or both surfaces of the electrode are bonded to the separator may be implemented in various forms as shown in FIGS. However, the present invention is not limited to the structures shown in Figs. The improved electrode may be one or more of a plurality of electrodes.

FIG. 3 schematically shows a first embodiment 210 in which a first separator 130 is bonded to one surface of an anode 110. FIG. 4 schematically shows a second embodiment 220 having a structure in which a first separator 130 is bonded to both surfaces of an anode 110. 5 shows a structure in which the anode 110, the first separator 130, and the cathode 120 are bonded to each other with the first separator 130 interposed between the anode 110 and the cathode 120 A third embodiment 230 is schematically illustrated. In FIG. 6, one electrode 110 of the outermost electrodes of the third embodiment 230 of FIG. 4 is bonded to the first separators 130 with the first separators 130 interposed therebetween Lt; RTI ID = 0.0 > 240 < / RTI > 7 shows a structure of a structure in which the outermost electrodes 110 and 120 of the third embodiment 230 of FIG. 4 are bonded to the separation membranes 130 in a state where the outermost electrodes 110 and 120 are interposed between the first separation membranes 130 5 embodiment (250) is schematically illustrated. In this case, the second embodiment 220 can be replaced with an electrode element, and the third embodiment 230 can be replaced with an electrode group.

The electrode stack 300 includes a plurality of anodes 110, a plurality of separators 130 and 140, a plurality of cathodes 120, a first embodiment 210, a second embodiment 220, , A third embodiment 230, a fourth embodiment 240, and a fifth embodiment 250. The embodiment of FIG.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (18)

At least one first separator interposed between electrodes of opposite polarity and having one or both surfaces laminated with the electrodes;
One or more second separation membranes interposed between electrodes of mutually opposite polarities, one or both surfaces being in contact with the electrodes in an unmated state;
At least one first electrode having a first electrode layer of high loading formed on a current collector and disposed on an outer side (outer side) of the electrode stack body with respect to the second separator film;
A second electrode material layer having a relatively low loading relative to the first electrode material layer is formed on the current collector and disposed on an inner side of the electrode stack body with respect to the second separator film At least one second electrode;
And an electrode layer laminated thereon. The method according to claim 1,
Wherein the loading amount of the first electrode material of the high loading ranges from 101% to 200% of the loading amount of the second electrode material of the low loading. The method according to claim 1,
Wherein the first electrodes are stacked in a state in which a first separator is interposed between an anode and a cathode and are disposed outside the electrode stack body with respect to the second separator,
Wherein the second electrodes are laminated with a first separator interposed between the positive electrode and the negative electrode and arranged inside the electrode laminate with respect to the second separator. The method of claim 3,
Wherein the first electrodes are stacked with a first separator interposed between the anode and the cathode, and are disposed on the outermost side of the electrode stack with respect to the second separator. The method according to claim 1,
The electrode laminate includes at least one anode, at least one cathode, and at least one first separator, and the anode, the first separator, and the cathode are bonded to each other with the first separator interposed between the anode and the cathode Wherein the electrode assembly comprises a plurality of electrode assemblies. 6. The method of claim 5,
Wherein the outermost electrodes of the electrode group have the same polarity. The method according to claim 6,
Wherein at least one of the outermost electrodes is bonded to the first separator interposed between the first separators. 6. The method of claim 5,
Wherein the polarities of the outermost electrodes of the electrode group are different from each other. 9. The method of claim 8,
Wherein at least one of the outermost electrodes is bonded to the first separator interposed between the first separators. The method according to claim 1,
Wherein the electrode laminate includes an electrode element including any one of an anode and a cathode and a first separator and in which one of an anode and a cathode and a first separator are bonded to each other. 11. The method of claim 10,
Wherein one of the positive electrode and the negative electrode is interposed between the first separating films and either one of the positive electrode and the negative electrode is bonded to the first separating film. The method according to claim 1,
Wherein the second separation film surrounds a side surface of the electrode which is a portion where the electrode tab is not formed. A battery, wherein the electrode laminate according to any one of claims 1 to 12 is embedded in a battery case together with an electrolyte. 14. The method of claim 13,
Wherein the battery case is a pouch-shaped battery case of a laminate sheet including a metal can or metal layer and a resin layer. 14. The method of claim 13,
Wherein the battery is one lithium secondary battery selected from the group consisting of a lithium ion polymer battery, a lithium ion battery, and a lithium polymer battery. A battery pack comprising the battery according to claim 13. A device comprising a battery pack according to claim 16. 18. The method of claim 17,
Wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in electric vehicle or a power storage device.

Images