Patent ID: 12199314

MODE FOR CARRYING OUT THE INVENTION

The objectives, specific advantages, and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. It should be noted that the reference numerals are added to the components of the drawings in the present specification with the same numerals as possible, even if they are illustrated in other drawings. Also, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. In the following description of the present invention, the detailed descriptions of related arts which may unnecessarily obscure the gist of the present invention will be omitted.

FIG.1is an exploded perspective view of a secondary battery to which an electrode assembly is applied according to a first embodiment of the present invention,FIG.2is a partial perspective view illustrating another example of an arrangement of a positive electrode tab in the electrode assembly according to the first embodiment of the present invention, andFIG.3is a front view illustrating an unfolded state before the electrode assembly is wound according to the first embodiment of the present invention.

Referring toFIGS.1and3, an electrode assembly100according to a first embodiment of the present invention comprises a positive electrode sheet110comprising a positive electrode active material portion112and a positive electrode non-coating portion113, a positive electrode tab150provided on the positive electrode non-coating portion113, a negative electrode sheet120comprising a negative electrode active material portion122and a negative electrode non-coating portion123, a negative electrode tab160provided on the negative electrode non-coating portion123, and a separator140provided between the positive electrode sheet110and the negative electrode sheet120.

FIG.4is a plan view illustrating a stacked state before the electrode assembly is wound according to the first embodiment of the present invention,FIG.5is a plan view illustrating an unfolded state before the positive electrode sheet110and the negative electrode sheet120are wound in the electrode assembly according to the first embodiment of the present invention, andFIG.6is a front view illustrating a main part in the state in which the electrode assembly is wound according to the first embodiment of the present invention.

Hereinafter, the electrode assembly according to the first embodiment of the present invention will be described in more detail with reference toFIGS.1to6.

Referring toFIGS.1and3, the electrode assembly100may be a chargeable and dischargeable power generation element and have a structure in which an electrode130and a separator140are combined and alternately stacked with each other. Here, the electrode assembly100may be an electrode assembly for a lithium ion secondary battery and may have a wound shape.

The electrode130may comprise the positive electrode sheet110and the negative electrode sheet120. Also, the separator140may electrically insulate the positive electrode sheet110from the negative electrode sheet120.

Also, the positive electrode sheet110and the negative electrode sheet120may be alternately stacked and wound together with the separator140and may be formed in a roll shape. Here, the electrode assembly100may be, for example, wound in a circular or oval shape so as to be formed in a jelly roll type.

Referring toFIGS.3to5, the positive electrode sheet110may comprise a positive electrode active material portion112that is an area on which a positive electrode active material is stacked on a positive electrode collector111and a positive electrode non-coating portion113that is an area on which a positive electrode active material is not stacked. Here, the positive electrode sheet110may be disposed, for example, in the form of a sheet.

For example, the positive electrode collector111may be provided as foil made of an aluminum (Al) material.

The positive electrode active material portion112may comprise a positive electrode active material stacked on one or more surfaces of one surface110cor the other surface110dof the positive electrode sheet110. Here, the positive electrode active material portion112may be disposed, for example, on both surfaces of the positive electrode sheet120. Also, the positive electrode active material portion112may further comprise a binder and a conductive material in addition to the positive electrode active material.

The positive electrode active material may comprise lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound containing at least one of these and mixtures thereof.

For another example, the positive electrode active material may comprise a Hi Ni-based positive electrode material. Here, the Hi Ni-based positive electrode material may comprise one or more of a LiNiMnCoO-based material, a LiNiCoAl-based material, and a LiMiMnCoAl-based material.

For example the binder may comprise one of polyfluoro vinylidene, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, and fluoro rubber.

For example, the conductive material may comprise one of: graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powder such as carbon fluorine, aluminum, and nickel powder; conductive whisker such as zinc oxide and potassium titanate; conductive oxide such as titanium oxide; and polyphenylene derivatives.

The positive electrode non-coating portion113may be divided into two portions spaced apart from each other and thus may comprise a first positive electrode non-coating portion113aand a second positive electrode non-coating portion113b. Here, the positive electrode non-coating portion113may be disposed on at least one surface of both surfaces of the positive electrode sheet110.

The first positive electrode non-coating portion113aand the second positive electrode non-coating portion113bmay be disposed between both sides in a longitudinal direction of the positive electrode sheet110.

Here, for example, the first positive electrode non-coating portion113amay be disposed close to one side portion110aof the positive electrode sheet110, and the second positive electrode non-coating portion113bmay be disposed close to the other side portion110bof the positive electrode sheet110.

Also, the first positive electrode non-coating portion113amay be disposed at a side of a winding outer portion, and the second positive electrode non-coating portion113bmay be disposed at a side of a winding central portion when the positive electrode sheet110is wound. The present invention is not necessarily limited thereto. For example, the first positive electrode non-coating portion113amay be disposed at the side of the winding central portion, and the second positive electrode non-coating portion113bmay be disposed at the side of the winding outer portion when the positive electrode sheet110is wound.

The positive electrode tab150is provided on the positive electrode non-coating portion113of the positive electrode sheet110. Here, one end of the positive electrode tab150may be attached and fixed to the positive electrode non-coating portion113, and the other end of the positive electrode tab150may protrude from the positive electrode sheet110.

Also, the positive electrode tab150may comprise a first positive electrode tab151provided on the first positive electrode non-coating portion113aand a second positive electrode tab152provided on the second positive electrode non-coating portion113b. Here, although the first positive electrode tab151and the second positive electrode tab152are illustrated as being disposed on the other surface110dof the positive electrode sheet110inFIG.3, the present invention is not necessarily limited thereto. For example, the first positive electrode tab151and the second positive electrode tab152may be disposed on one surface110cor the other surface110dof the positive electrode sheet110, respectively. Here, for another example, the first positive electrode tab151and the second positive electrode tab152may be disposed on the one surface110cof the positive electrode sheet110.

Referring toFIG.1, for example, the first positive electrode tab151and the second positive electrode tab152may be disposed at both sides of a winding central axis C in the wound electrode assembly100.

Referring toFIG.2, in the positive electrode tab150, a first positive electrode tab151′ and a second positive electrode tab152may be disposed at one side with respect to the winding central axis C in an electrode assembly100′ that is wound according to another embodiment. That is, in the winding central axis C, the first positive electrode tab151′ and the second positive electrode tab152may be sequentially arranged in a direction of an outer circumferential surface of the electrode assembly100′. Here, the first positive electrode tab151′ and the second positive electrode tab152may be arranged on a line extending in a direction perpendicular to the winding central axis C.

Referring toFIGS.3to5, the negative electrode sheet120may comprise a negative electrode active material portion122that is an area on which a negative electrode active material is stacked on the negative electrode collector121and a negative electrode non-coating portion123that is an area on which the negative electrode active material is not stacked. Here, the negative electrode sheet120may be provided in, for example, the form of a sheet.

For example, the negative electrode collector121may be foil made of a copper (Cu) or nickel (Ni) material.

The negative electrode active material portion122may comprise a negative electrode active material stacked on one or more of one surface120cor the other surface120dof the negative electrode sheet120. Here, the negative electrode active material portion122may be disposed on, for example, both surfaces of the negative electrode sheet120. Also, the negative electrode active material portion122may further comprise a binder and a conductive material in addition to the negative electrode active material.

For example, the negative electrode active material may be made of a material comprising synthetic graphite.

For another example, the negative electrode active material may comprise lithium a metal, a lithium alloy, carbon, petroleum coke, activated carbon, graphite, a silicon compound, a tin compound, a titanium compound, or an alloy thereof.

The negative electrode non-coating portion123may comprise a first negative electrode non-coating portion123adisposed between both sides in a longitudinal direction of the negative electrode sheet120and second and third negative electrode non-coating portions123band123cdisposed at both sides of the negative electrode sheet120. Here, the negative electrode non-coating portion123may be disposed on at least one surface of both surfaces of the negative electrode sheet120.

Referring toFIGS.3,5, and6, the first positive electrode non-coating portion113aand the first negative electrode non-coating portion123amay be disposed at positions corresponding to each other.

Referring toFIGS.3to5, the negative electrode tab160is disposed on the negative electrode non-coating portion123. Here, one end of the negative electrode tab160may be attached and fixed to the negative electrode non-coating portion123, and the other end of the negative electrode tab160may protrude from the negative electrode sheet120.

Also, the negative electrode tab160comprise a first negative electrode tab161provided on the first negative electrode non-coating portion123a, a second negative electrode tab162provided on the second negative electrode non-coating portion123b, and a third negative electrode tab163disposed on the third negative electrode non-coating portion123c. Here, although the first negative electrode tab161and the second negative electrode tab162are illustrated as being disposed on the one surface120cof the negative electrode sheet120inFIG.3, the present invention is not necessarily limited thereto. For example, the first negative electrode tab161, the second negative electrode tab162, and the third negative electrode tab163may be disposed on the one surface120cor the other surface120dof the negative electrode sheet120, respectively. Here, for another example, the first negative electrode tab161and the second negative electrode tab162may be disposed on the other surface120dof the negative electrode sheet120, and the third negative electrode tab163may be disposed on one surface120cof the negative electrode sheet120.

Referring toFIGS.1,3, and6, the separator140is made of an insulation material and alternately stacked with the positive electrode sheet110and the negative electrode sheet120. Here, the separator140may be disposed between the positive electrode sheet110and the negative electrode sheet120and on outer surfaces of the positive electrode sheet110and the negative electrode sheet120.

Also, the separator140may be made of, for example, a material having uniform fine pores. Here, the separator140may be, for example, a multi-layer film produced by microporous polyethylene, polypropylene, or a combination thereof or a polymer film for solid polymer electrolytes or gel-type polymer electrolytes such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride hexafluoropropylene copolymers.

Also, the separator140may comprise a first separator141disposed between the one surface110cof the positive electrode sheet110and the other surface120dof the negative electrode sheet120and a second separator142disposed on the one surface120cof the negative electrode sheet120.

Referring toFIGS.1,4, and5, the first positive electrode tab151and the first negative electrode tab161may be disposed so as not to overlap each other with respect to a direction in which the positive electrode sheet110and the negative electrode sheet120face each other. Here, the direction in which the positive electrode sheet110and the negative electrode sheet120face each other may be, for example, a side direction S of the winding central axis C.

Also, the first positive electrode tab151may protrude in one side direction C1with respect to a direction parallel to the winding central axis C, which is a central axis around which the electrode assembly100is wound, and the first negative electrode tab161may protrude in the other side direction C2with respect to the direction parallel to the winding central axis C. Here, referring toFIG.1, for example, the first positive electrode tab151may protrude upward from the electrode assembly100so as to be connected to a cap assembly12, and the first negative electrode tab161may protrude downward from the electrode assembly100so as to be connected to an inner bottom surface of the battery case11.

Also, ends of the first positive electrode tab151and the first negative electrode tab161may be spaced a predetermined distance from each other with respect to the direction parallel to the winding central axis C so as not to overlap each other.

Referring toFIGS.1,3, and6, one surface110cand120cof both surfaces of each of the positive electrode sheet110and the negative electrode sheet120may disposed inward S1during the winding, and the other surface110dand120dof both surface of each of the positive electrode sheet110and the negative electrode sheet120may be disposed outward S2from the winding side. Here, the first positive electrode tab151may be disposed on the other surface110dof the positive electrode sheet110, and the first negative electrode tab161may be disposed on the one surface120cof the negative electrode sheet120.

Also, in the positive electrode sheet110and the negative electrode sheet120, for example, the one side portions110aand120athereof may be wound to be disposed at the winding outer portion, and the other side portions110band120bmay be disposed at the winding central portion. Here, the positive electrode sheet110and the negative electrode sheet120may be wound around the other side portions110band120b. Here, the winding central portion may be a central region after the positive electrode sheet110and the negative electrode sheet120are wound, and the winding outer portion may be an outer region after the positive electrode sheet110and the negative electrode sheet120are wound. Here, referring toFIG.3, a winding direction R of the positive electrode sheet110and the negative electrode sheet120may be, for example, a clockwise direction. That is, in the positive electrode sheet110and the negative electrode sheet120, the one side portions110aand120amay be wound in a clockwise direction with respect to the other side portions110band120b.

However, the present invention is not necessarily limited thereto. For another example, in the positive electrode sheet110and the negative electrode sheet120, the one side portions110aand120aof both the sides may be wound to be disposed at the winding central portion, and the other side portions110band120bmay be disposed at the winding outer portion. Here, the positive electrode sheet110and the negative electrode sheet120may be wound around the one side portions110aand120a. That is, the positive electrode sheet110and the negative electrode sheet120may be wound in a direction opposite to that of the above-described example. Here, a winding direction R′ of the positive electrode sheet110and the negative electrode sheet120may be, for example, a counterclockwise direction.

Also, the first positive electrode non-coating portion113aand the second positive electrode non-coating portion113bmay be disposed between both sides of the positive electrode sheet110, and the first positive electrode non-coating portion113amay be disposed on the one side portion110aof the positive electrode sheet110.

Referring toFIGS.3and4, in the electrode assembly100according to the first embodiment of the present invention, a positive electrode insulation tape170may be further attached to the positive electrode non-coating portion113to cover the positive electrode tab150, and a negative electrode insulation tape180may be further attached to the negative electrode non-coating portion123to cover the negative electrode tab160. Here, the positive electrode insulation tape170made of an insulation material and a negative electrode insulation tape180made of an insulation material are provided to cover the positive electrode tab150and the negative electrode tab160, thereby preventing the separator140from being ruptured by edges of the positive electrode tab150and the negative electrode tab160and also preventing short circuit from occurring due to direct contact between the positive electrode tab150and the negative electrode sheet120or direct contact between the negative electrode tab160and the positive electrode sheet110through the damaged portion when the separator is damaged.

The positive electrode insulation tape170may comprise a first positive electrode insulation tape171attached to the first positive electrode non-coating portion113ato cover the first positive electrode tab151and a second positive electrode insulation tape182attached to the second positive electrode non-coating portion113bto cover the second positive electrode tab152.

The negative electrode insulation tape180may comprise a first negative electrode insulation tape181attached to the first negative electrode non-coating portion123ato cover the first negative electrode tab161, a second negative electrode insulation tape182attached to the second negative electrode non-coating portion123bto cover the second negative electrode tab162, and a third negative electrode insulation tape183attached to the third negative electrode non-coating portion123cto cover the third negative electrode tab163. Also, the negative electrode insulation tape180may further comprise a fourth negative electrode insulation tape184attached to a surface opposite to the surface on which the second negative electrode tab162is disposed on the second negative electrode non-coating portion123b. That is, the second negative electrode non-coating portion123bmay be disposed on both sides of the negative electrode sheet120. Here, the second negative electrode tab162may be disposed on one surface of the second negative electrode non-coating portion123b, and the fourth negative electrode insulation tape184may be disposed on the other surface of the second negative electrode non-coating portion123b.

Also, each of the positive electrode insulation tape170and the negative electrode insulation tape180may comprise an electrical insulation material. Here, the positive electrode insulation tape170and the negative electrode insulation tape180may not have pores through which lithium ions are movable. Thus, the positive electrode insulation tape170and the negative electrode insulation tape180may be made of a material that is resistant to the physical damage and thus may not be damaged by the edges of the positive electrode tab150and the negative electrode tab160. In addition, portions of the separator140facing the positive electrode tab150and the negative electrode tab160may be prevented from being damaged.

The positive electrode insulation tape170and the negative electrode insulation tape180may comprise, for example, a base material (not shown) and an adhesion layer (not shown) disposed on one surface of the base material.

Referring toFIGS.3and6, in the electrode assembly100according to the first embodiment of the present invention, a lithium ion deposition prevention tape190may be further attached on a portion of the positive electrode sheet110which faces the first negative electrode insulation tape181with the separator140therebetween. Here, the lithium ion deposition prevention tape190may be provided on, for example, the other surface110dof the positive electrode sheet110, particularly, disposed on a surface of the positive electrode active material112stacked between the one side portion110aof the positive electrode sheet110and the first positive electrode non-coating portion113athat is disposed close to the one side portion110aof the positive electrode sheet110. Here, the lithium ion deposition prevention tape190and the first negative electrode non-coating portion123amay face each other with the second separator142therebetween. Also, the lithium ion deposition prevention tape190may be made of an electrical insulation material.

Thus, the lithium ion deposition prevention tape190may be disposed on a portion of the positive electrode sheet110facing the first negative electrode non-coating portion123a, to which the first negative electrode insulation tape181is attached, to prevent lithium ions, which are not exchanged, from being accumulated to be deposited during the charging and discharging.

That is, the lithium ion deposition prevention tape190may be attached to the surface of the positive electrode active material portion112of the positive electrode sheet110facing the first negative electrode insulation tape181to prevent the lithium ions from being accumulated to be deposited on the portion at which the lithium ions are not exchanged by the first negative electrode insulation tape181when the lithium ion are exchanged to perform the charging and the discharging.

In more detail, the separator140may have a thin film form and be disposed between the positive electrode sheet110and the negative electrode sheet120to prevent the positive electrode sheet110and the negative electrode sheet120from directly contacting each other. Here, the lithium ions may move through the fin pores of the separator140to perform the charging and the discharging. Here, the first negative electrode insulation tape181is made of an insulation material having no fine pores, and thus, the lithium ions do not move therethrough. Here, the lithium ions that do not move by being blocked by the first negative electrode insulation tape181may be accumulated to be deposited on the surface of the positive electrode active material portion112of the positive electrode sheet110facing the first t negative electrode insulation tape181. Thus, in the electrode assembly100according to the first embodiment of the present invention, the lithium ion deposition prevention tape made of the insulation material may be attached to the surface of the positive electrode active material portion112of the positive electrode sheet110to prevent facing the first negative electrode insulation tape181to prevent the lithium ions from being accumulated on the surface of the positive electrode active material portion112facing the first negative electrode insulation tape181.

The lithium ion deposition prevention tape190may be made of, for example, polyimide (PI).

Also, the lithium ion deposition prevention tape190may comprise, for example, a base material (not shown) and an adhesion layer (not shown) disposed on one surface of the base material.

Referring toFIG.3, the electrode assembly100according to the first embodiment of the present invention configured as described above may reduce resistance by adding the first negative electrode tab161such that the number of negative electrode tabs160is greater than that of the positive electrode tabs150.

Here, the first negative electrode non-coating portion123amay be additionally provided to attach the first negative electrode tab161, and the first negative electrode non-coating portion123amay be disposed to correspond to the first positive electrode non-coating portion113aon which the first positive electrode tab151is disposed, thereby preventing or significantly reducing the additional loss of the battery capacity. That is, when the negative electrode non-coating portion is additionally provided, if the positive electrode non-coating portion is additionally provided on the positive electrode sheet110to correspond to the formation of the first negative electrode non-coating portion123a, the positive electrode active material portion122may be reduced to decrease in battery capacity. Therefore, the first negative electrode non-coating portion123amay match the first positive electrode non-coating portion113aon which the first positive electrode tab151is disposed so that the positive electrode non-coating portion is additionally provided, thereby significantly reducing or preventing the decrease of the battery capacity.

Hereinafter, an electrode assembly according to a second exemplary embodiment of the present invention will be described.

FIG.7is a front view illustrating an unfolded state before an electrode assembly is wound according to a second embodiment of the present invention.

Referring toFIG.7, an electrode assembly200according to a second embodiment of the present invention comprises a positive electrode sheet210comprising a positive electrode active material portion212and a positive electrode non-coating portion213, a positive electrode tab250provided on the positive electrode non-coating portion213, a negative electrode sheet220comprising a negative electrode active material portion222and a negative electrode non-coating portion223, a negative electrode tab260provided on the negative electrode non-coating portion223, and a separator140provided between the positive electrode sheet210and the negative electrode sheet220.

The electrode assembly200according to the second embodiment of the present invention is different from the electrode assembly100according to the first embodiment of the present invention in positions of the positive electrode non-coating portion213and the negative electrode non-coating portion223. Thus, this embodiment briefly describes the contents overlapping with the above-described embodiment and will be described based on the differences.

In more detail, the positive electrode sheet210may comprise a positive electrode active material portion212that is an area on which a positive electrode active material is stacked on a positive electrode collector211and a positive electrode non-coating portion213that is an area on which the positive electrode active material is not stacked.

The positive electrode non-coating portion213may be divided into two portions spaced apart from each other and thus may comprise a first positive electrode non-coating portion213aand a second positive electrode non-coating portion213b. Here, the positive electrode non-coating portion213may be disposed on at least one surface of both surfaces of the positive electrode sheet210.

The first positive electrode non-coating portion213aand the second positive electrode non-coating portion213bmay be disposed between both sides in a longitudinal direction of the positive electrode sheet210.

Here, for example, the first positive electrode non-coating portion213amay be disposed close to the other side portion210bof the positive electrode sheet210, and the second positive electrode non-coating portion213bmay be disposed close to one side portion210aof the positive electrode sheet210.

Also, the first positive electrode non-coating portion213amay be disposed at a side of a winding outer portion, and the second positive electrode non-coating portion213bmay be disposed at a side of a winding central portion when the positive electrode sheet210is wound. The present invention is not necessarily limited thereto. For example, the first positive electrode non-coating portion213amay be disposed at the side of the winding central portion, and the second positive electrode non-coating portion213bmay be disposed at the side of the winding outer portion when the positive electrode sheet210is wound.

The positive electrode tab250is provided on the positive electrode non-coating portion213of the positive electrode sheet210. Here, one end of the positive electrode tab250may be attached and fixed to the positive electrode non-coating portion213, and the other end of the positive electrode tab150may protrude from the positive electrode sheet210.

Also, the positive electrode tab250may comprise a first positive electrode tab251provided on the first positive electrode non-coating portion213aand a second positive electrode tab252provided on the second positive electrode non-coating portion213b.

The negative electrode sheet220may comprise a negative electrode active material portion222that is an area on which a negative electrode active material is stacked on the negative electrode collector221and a negative electrode non-coating portion223that is an area on which the negative electrode active material is not stacked.

The negative electrode non-coating portion223may comprise a first negative electrode non-coating portion223adisposed between both sides in a longitudinal direction of the negative electrode sheet220and second and third negative electrode non-coating portions223band223cdisposed at both sides of the negative electrode sheet220. Here, the negative electrode non-coating portion223may be disposed on at least one surface of both surfaces of the negative electrode sheet220.

The first positive electrode non-coating portion213band the first negative electrode non-coating portion223amay be disposed corresponding to each other.

The negative electrode tab260is disposed on the negative electrode non-coating portion223. Here, one end of the negative electrode tab260may be attached and fixed to the negative electrode non-coating portion223, and the other end of the negative electrode tab160may protrude from the negative electrode sheet220.

Also, the negative electrode tab260may comprise a first negative electrode tab261provided on the first negative electrode non-coating portion223a, a second negative electrode tab262provided on the second negative electrode non-coating portion123b, and a third negative electrode tab263disposed on the third negative electrode non-coating portion123c.

In the electrode assembly200according to the second embodiment of the present invention, a positive electrode insulation tape270may be further attached to the positive electrode non-coating portion213to cover the positive electrode tab250, and a negative electrode insulation tape280may be further attached to the negative electrode non-coating portion223to cover the negative electrode tab260.

The positive electrode insulation tape270may comprise a first positive electrode insulation tape271attached to the first positive electrode non-coating portion213ato cover the first positive electrode tab251and a second positive electrode insulation tape272attached to the second positive electrode non-coating portion213bto cover the second positive electrode tab252.

The negative electrode insulation tape comprise a first negative electrode insulation tape281attached to the first negative electrode non-coating portion223ato cover the first negative electrode tab261, a second negative electrode insulation tape282attached to the second negative electrode non-coating portion223bto the second negative electrode tab262, and a third negative electrode insulation tape283attached to the third negative electrode non-coating portion223cto cover the third negative electrode tab263. Also, the negative electrode insulation tape280may further comprise a fourth negative electrode insulation tape284attached to a surface opposite to the surface on which the second negative electrode tab262is disposed on the second negative electrode non-coating portion223b. That is, the second negative electrode non-coating portion223bmay be disposed on both sides of the negative electrode sheet220. Here, the second negative electrode tab262may be disposed on one surface of the second negative electrode non-coating portion223b, and the fourth negative electrode insulation tape284may be disposed on the other surface of the second negative electrode non-coating portion223b.

Hereinafter, an electrode assembly according to a third embodiment will be described with reference toFIGS.8and9.

FIG.8is a front view illustrating an unfolded state before an electrode assembly is wound according to a third embodiment of the present invention, andFIG.9is a front view illustrating a main part in the state in which the electrode assembly is wound according to the third embodiment of the present invention.

Referring toFIGS.8and9, an electrode assembly300according to a third embodiment of the present invention comprises a positive electrode sheet310comprising a positive electrode active material portion312and a positive electrode non-coating portion313, a positive electrode tab350provided on the positive electrode non-coating portion313, a negative electrode sheet320comprising a negative electrode active material portion322and a negative electrode non-coating portion323, a negative electrode tab360provided on the negative electrode non-coating portion323, and a separator140provided between the positive electrode sheet310and the negative electrode sheet320.

The electrode assembly300according to the third embodiment of the present invention is different from the electrode assembly100according to the first embodiment and the electrode assembly according to the second embodiment in winding shape. Thus, this embodiment briefly describes the contents overlapping with the above-described embodiment and will be described based on the differences.

In more detail, the positive electrode sheet310may comprise a positive electrode active material portion312that is an area on which a positive electrode active material is stacked on a positive electrode collector311and a positive electrode non-coating portion113that is an area on which a positive electrode active material is not stacked.

The positive electrode non-coating portion313may be divided into two portions spaced apart from each other and thus may comprise a first positive electrode non-coating portion313aand a second positive electrode non-coating portion313b. Here, the positive electrode non-coating portion313may be disposed on at least one surface of both surfaces of the positive electrode sheet310.

The first positive electrode non-coating portion313aand the second positive electrode non-coating portion313bmay be disposed between both sides in a longitudinal direction of the positive electrode sheet310.

Here, for example, the first positive electrode non-coating portion313amay be disposed close to one side portion310aof the positive electrode sheet310, and the second positive electrode non-coating portion113bmay be disposed close to the other side portion310bof the positive electrode sheet310.

Also, the first positive electrode non-coating portion313amay be disposed at a side of a winding central portion, and the second positive electrode non-coating portion313bmay be disposed at a side of a winding outer portion when the positive electrode sheet310is wound. However, the present invention is not necessarily limited thereto. For example, the first positive electrode non-coating portion313amay be disposed at the side of the winding outer portion, and the second positive electrode non-coating portion313bmay be disposed at the side of the winding central portion when the positive electrode sheet310is wound.

The positive electrode tab350is provided on the positive electrode non-coating portion313of the positive electrode sheet310. Here, one end of the positive electrode tab350may be attached and fixed to the positive electrode non-coating portion313, and the other end of the positive electrode tab150may protrude from the positive electrode sheet310.

Also, the positive electrode tab350may comprise a first positive electrode tab351provided on the first positive electrode non-coating portion313aand a second positive electrode tab352provided on the second positive electrode non-coating portion313b. Here, for example, the first positive electrode tab351and the second positive electrode tab352may be disposed on the other surface310dof the positive electrode sheet310.

Here, although the first positive electrode tab351and the second positive electrode tab352are illustrated as being disposed on the other surface110dof the positive electrode sheet310inFIG.9, the present invention is not necessarily limited thereto. For example, the first positive electrode tab351and the second positive electrode tab352may be disposed on one surface310cor the other surface310dof the positive electrode sheet310, respectively. Here, for another example, the first positive electrode tab351and the second positive electrode tab352may be disposed on the one surface310cof the positive electrode sheet310.

The negative electrode sheet320may comprise a negative electrode active material portion322that is an area on which a negative electrode active material is stacked on the negative electrode collector321and a negative electrode non-coating portion323that is an area on which the negative electrode active material is not stacked.

The negative electrode non-coating portion323may comprise a first negative electrode non-coating portion323adisposed between both sides in a longitudinal direction of the negative electrode sheet320and second and third negative electrode non-coating portions323band323cdisposed at both sides of the negative electrode sheet320. Here, the negative electrode non-coating portion323may be disposed on at least one surface of both surfaces of the negative electrode sheet320.

The first positive electrode non-coating portion313band the first negative electrode non-coating portion323amay be disposed corresponding to each other.

The negative electrode tab360is disposed on the negative electrode non-coating portion323. Here, one end of the negative electrode tab360may be attached and fixed to the negative electrode non-coating portion323, and the other end of the negative electrode tab160may protrude from the negative electrode sheet320.

Also, the negative electrode tab360may comprise a first negative electrode tab361provided on the first negative electrode non-coating portion323a, a second negative electrode tab362provided on the second negative electrode non-coating portion323b, and a third negative electrode tab363disposed on the third negative electrode non-coating portion323c. Here, although the first negative electrode tab361and the second negative electrode tab362are illustrated as being disposed on the one surface320cof the negative electrode sheet320inFIG.8, the present invention is not necessarily limited thereto. For example, the first negative electrode tab361, the second negative electrode tab362, and the third negative electrode tab363may be disposed on the one surface320cor the other surface320dof the negative electrode sheet320, respectively. Here, for another example, the first negative electrode tab361and the second negative electrode tab362may be disposed on the other surface320dof the negative electrode sheet320, and the third negative electrode tab363may be disposed on the one surface320cof the negative electrode sheet320.

The one surfaces310cand320cof both the surfaces of the positive electrode sheet310and the negative electrode sheet320may be disposed outward during the winding, and the other surfaces310dand320dmay be disposed inward from the winding side. Here, the first positive electrode tab351may be disposed on the other surface110dof the positive electrode sheet310, and the first negative electrode tab361may be disposed on the one surface320cof the negative electrode sheet320.

Also, in the positive electrode sheet310and the negative electrode sheet320, for example, the other side portions310band320bof both the side portions may be wound to be disposed at a winding central portion, and one side portions310aand320amay be wound to be disposed at a winding outer portion. Here, the positive electrode sheet310and the negative electrode sheet320may be wound from the other side portions310band320bso as to be wound in direction of the one side portions310aand320a, i.e., wound in a clockwise direction. Here, the winding direction R of the positive electrode sheet310and the negative electrode sheet320may be, for example, a clockwise direction.

However, the present invention is not necessarily limited thereto. For another example, in the positive electrode sheet310and the negative electrode sheet320, the one side portions310aand320aof both the sides may be wound to be disposed at the winding central portion, and the other side portions310a320abe disposed at the winding outer portion. Here, the positive electrode sheet310and the negative electrode sheet320may be wound around the other side portions310band320b. That is, the positive electrode sheet310and the negative electrode sheet320may be wound in a direction opposite to that of the above-described example. Here, a winding direction R′ of the positive electrode sheet310and the negative electrode sheet320may be, for example, a counterclockwise direction.

In the electrode assembly300according to the third embodiment of the present invention, a positive electrode insulation tape370may be further attached to the positive electrode non-coating portion313to cover the positive electrode tab350, and a negative electrode insulation tape380may be further attached to the negative electrode non-coating portion323to cover the negative electrode tab360.

The positive electrode insulation tape370may comprise a first positive electrode insulation tape371attached to the first positive electrode non-coating portion313ato cover the first positive electrode tab351and a second positive electrode insulation tape372attached to the second positive electrode non-coating portion313bto cover the second positive electrode tab352.

The negative electrode insulation tape380may comprise a first negative electrode insulation tape381attached to the first negative electrode non-coating portion323ato cover the first negative electrode tab361, a second negative electrode insulation tape382attached to the second negative electrode non-coating portion323bto the second negative electrode tab362, and a third negative electrode insulation tape383attached to the third negative electrode non-coating portion323cto cover the third negative electrode tab363. Also, the negative electrode insulation tape380may further comprise a fourth negative electrode insulation tape384attached to a surface opposite to the surface on which the second negative electrode tab362is disposed on the second negative electrode non-coating portion323b. That is, the second negative electrode non-coating portion323bmay be disposed on both sides of the negative electrode sheet320. Here, the second negative electrode tab362may be disposed on one surface of the second negative electrode non-coating portion323b, and the fourth negative electrode insulation tape384may be disposed on the other surface of the second negative electrode non-coating portion323b.

In the electrode assembly300according to the first embodiment of the present invention, a lithium ion deposition prevention tape390may be further attached on a portion of the positive electrode sheet310which: faces the first negative electrode insulation tape381with the separator140therebetween.

Hereinafter, a secondary battery comprising the electrode assembly according to an embodiment of the present invention will be described with reference toFIGS.1to6.

Referring toFIGS.1and2, a secondary battery10according to an embodiment of the present invention comprises an electrode assembly100and a battery case11accommodating the electrode assembly100. Here, the electrode assembly100comprises a positive electrode sheet110comprising a positive electrode active material portion112and a positive electrode non-coating portion113, a positive electrode tab150provided on the positive electrode non-coating portion113, a negative electrode sheet120comprising a negative electrode active material portion122and a negative electrode non-coating portion123, a negative electrode tab160provided on the negative electrode non-coating portion123, and a separator140provided between the positive electrode sheet110and the negative electrode sheet120.

The secondary battery according to an embodiment of the present invention relates to the secondary battery10comprising the electrode assembly according to the first to third embodiments. This embodiment briefly describes the contents overlapping with the above-described embodiment, and will be described based on the differences.

In more detail, referring toFIG.1, in the secondary battery10according to an embodiment of the present invention, the battery case11may have an accommodation part11athat accommodates an electrolyte and the electrode assembly100therein. Here, the battery case11may be opened in a shape in which the accommodation part11ais opened to one side. Also, a cap assembly12may be further provided to cover the opened one side of the battery case11. Here, the battery case11may have, for example, an oval shape or a cylindrical shape.

Also, the electrode assembly100may be a chargeable and dischargeable power generation element and have a structure in which an electrode130and a separator140are combined and alternately stacked. Here, the electrode assembly100may be an electrode assembly for a lithium ion secondary battery and may have a wound shape.

The electrode130may comprise the positive electrode sheet110and the negative electrode sheet120. Also, the separator140may electrically insulate the positive electrode sheet110from the negative electrode sheet120.

Referring toFIGS.1to4, the positive electrode sheet110may comprise a positive electrode active material portion112that is an area on which a positive electrode active material is stacked on a positive electrode collector111and a positive electrode non-coating portion113that is an area on which a positive electrode active material is not stacked. Here, the positive electrode non-coating portion113may be divided into two portions spaced apart from each other on the positive electrode sheet110and thus may comprise a first positive electrode non-coating portion113aand a second positive electrode non-coating portion113b.

The positive electrode tab150is provided on the positive electrode non-coating portion113of the positive electrode sheet110. Here, one end of the positive electrode tab150may be attached and fixed to the positive electrode non-coating portion113, and the other end of the positive electrode tab150may protrude from the positive electrode sheet110. Here, the positive electrode tab150may protrude toward a bottom surface of the cap assembly12or the battery case11.

Also, the positive electrode tab150may comprise a first positive electrode tab151provided on the first positive electrode non-coating portion113aand a second positive electrode tab152provided on the second positive electrode non-coating portion113b.

The negative electrode sheet120may comprise a negative electrode active material portion122that is an area on which a negative electrode active material is stacked on the negative electrode collector121and a negative electrode non-coating portion123that is an area on which the negative electrode active material is not stacked. Here, the negative electrode non-coating portion123may comprise a first negative electrode non-coating portion123adisposed between both sides of the negative electrode sheet120and second and third negative electrode non-coating portions123band123cdisposed at both sides of the negative electrode sheet120. Here, the first negative electrode non-coating portion123amay be disposed on one side portion120aof the negative electrode sheet120, and the second negative electrode non-coating portion123bmay be disposed on the other side portion120bof the negative electrode sheet120.

The negative electrode tab160is disposed on the negative electrode non-coating portion123. Here, one end of the negative electrode tab160may be attached and fixed to the negative electrode non-coating portion123, and the other end of the negative electrode tab160may protrude from the negative electrode sheet120. Here, the negative electrode tab160may protrude toward a bottom surface of the cap assembly12or the battery case11.

Also, the negative electrode tab160may comprise a first negative electrode tab161provided on the first negative electrode non-coating portion123a, a second negative electrode tab162provided on the second negative electrode non-coating portion123b, and a third negative electrode tab163disposed on the third negative electrode non-coating portion123c.

Here, the first positive electrode non-coating portion213band the first negative electrode non-coating portion123amay be disposed corresponding to each other.

Also, referring toFIG.5, the first positive electrode tab151and the first negative electrode tab161may be disposed so as not to overlap each other with respect to a direction in which the positive electrode sheet110and the negative electrode sheet120face each other.

Referring toFIGS.3and6, in the electrode assembly100of the secondary battery10according to an embodiment of the present invention, a first negative electrode insulation tape181may be further attached to the first negative electrode non-coating portion123ato cover the first negative electrode tab161.

Also, in the electrode assembly100of the secondary battery10according to an embodiment of the present invention, a lithium ion deposition prevention tape190may be further attached to a portion of the positive electrode sheet10facing the first negative electrode non-coating portion123a.

Thus, the lithium ion deposition prevention tape190may be disposed on a portion of the positive electrode sheet110facing the first negative electrode non-coating portion123a, to which the first negative electrode insulation tape181is attached, to prevent lithium ions, which are not exchanged, from being accumulated to be deposited during the charging and discharging.

That is, the lithium ion deposition prevention tape190may be attached to the surface of the positive electrode active material portion112of the positive electrode sheet110facing the first negative electrode insulation tape181to prevent the lithium ions from being accumulated and deposited on the portion at which the lithium ions are not exchanged by the first negative electrode insulation tape181when the lithium ion are exchanged to perform the charging and the discharging.

FIG.10is a perspective view illustrating an unfolded state before a positive electrode plate and a negative electrode plate are wound in an electrode assembly according to a fourth embodiment of the present invention.

Hereinafter, an electrode assembly according to a fourth embodiment will be described with reference toFIG.10.

Referring toFIG.10, an electrode assembly1100according to a fourth embodiment of the present invention comprises a positive electrode plate1110comprising a positive electrode active material portion1112and a positive electrode non-coating portion1113, a positive electrode tab1150disposed on the positive electrode non-coating portion1113, a negative electrode plate1120comprising a negative electrode active material portion1122and a negative electrode non-coating portion1123, a negative electrode tab1160disposed on the negative electrode non-coating portion1123, and a separator1140disposed between the positive electrode plate1110and the negative electrode plate1120.

The electrode assembly1100may be a chargeable and dischargeable power generation element and have a structure in which an electrode1130and the separator1140are combined and alternately stacked. Here, the electrode assembly1100may be an electrode assembly for a lithium ion secondary battery and may have a wound shape.

The electrode1130may comprise the positive electrode plate1110and the negative electrode1120. Also, the separator1140may separate the positive electrode plate1110and the negative electrode plate1120from each other so that the positive electrode plate1110and the negative electrode plate1120are electrically insulated from each other.

Also, the positive electrode plate1110and the negative electrode plate1120may be alternately stacked and wound together with the separator1140and may be provided in the form of a roll. Here, the electrode assembly1100may be, for example, wound in a circular or oval shape so as to be formed in a jelly roll type.

The positive electrode plate1110may comprise a positive electrode collector1111, a positive electrode active material portion1112that is an area on which a positive electrode active material is stacked on the positive electrode collector1111, and a positive electrode non-coating portion1113that is an area on which the positive electrode active material is not stacked.

For example, the positive electrode collector1111may be provided as foil made of an aluminum (Al) material.

The positive electrode active material portion1112may comprise a positive electrode active material stacked on a first surface M12of the positive electrode collector1111. Also, the positive electrode active material portion1112may further comprise a positive electrode active material stacked on a second surface of the positive electrode collector1111. Also, the positive electrode active material portion1112may further comprise a binder and a conductive material in addition to the positive electrode active material.

For example, the positive electrode non-coating portion1113may be divided into two portions spaced apart from each other and thus may comprise a first positive electrode non-coating portion1113aand a second positive electrode non-coating portion1113b. Here, the first positive electrode non-coating portion1113amay be disposed between both ends of the positive electrode plate1110.

For another example, the positive electrode non-coating portion1113may be divided into three portions spaced apart from each other and thus may comprise a first positive electrode non-coating portion1113a, a second positive electrode non-coating portion1113b, and a third positive electrode non-coating portion1113c. Here, the first positive electrode non-coating portion1113amay be disposed between both ends of the positive electrode plate1110.

The positive electrode tab1150may be disposed on the positive electrode non-coating portion1113of the positive electrode plate1110. Also, the positive electrode tab1150may comprise a first positive electrode tab1151disposed on the first positive electrode non-coating portion113a. Here, one end of the first positive electrode tab1151may be attached and fixed to the first positive electrode non-coating portion1113a, and the other end of the first positive electrode tab1151may protrude from the positive electrode plate1110. Furthermore, the positive electrode tab1150may further comprise a second positive electrode tab (not shown) disposed on the second positive electrode non-coating portion1113b.

The negative electrode plate1210may comprise a negative electrode collector1121, a negative electrode active material portion1122that is an area on which a negative electrode active material is stacked and a negative electrode non-coating portion1123that is an area on which the negative electrode active material is not stacked.

For example, the negative electrode collector1121may be foil made of a copper (Cu) or nickel (Ni) material.

The negative electrode active material portion1122may comprise a negative electrode active material stacked on a first surface M21of the negative electrode collector1121. Here, the first surface M21of the negative electrode collector may be a surface facing the first surface M12of the positive electrode collector1111. That is, although the first surface M21of the negative electrode collector1122is illustrated in the same direction as the first surface M12of the positive electrode collector1111, for convenience of description inFIG.6, the first surface M21of the negative electrode collector1121may be substantially a surface facing the first surface M12of the positive electrode collector1111. Also, the negative electrode active material portion1122may further comprise a negative electrode active material stacked on a second surface of the negative electrode collector1121. Also, the negative electrode active material portion1122may further comprise a binder and a conductive material in addition to the negative electrode active material.

The negative electrode non-coating portion1123may comprise a first negative electrode non-coating portion1123adisposed between both ends of the negative electrode plate1120and second and third negative electrode non-coating portions1123band1123cdisposed at both ends of the negative electrode plate1120.

Also, the first positive electrode non-coating portion1113band the first negative electrode non-coating portion1123amay be disposed corresponding to each other.

The negative electrode tab1160is disposed on the negative electrode non-coating portion1123. Here, one end of the negative electrode tab1160may be attached and fixed to the negative electrode non-coating portion1123, and the other end of the negative electrode tab1160may protrude from the negative electrode plate1120. Also, the negative electrode tab1160may comprise a first negative electrode tab1161provided on the first negative electrode non-coating portion1123a, a second negative electrode tab1152provided on the second negative electrode non-coating portion1123b, and a third negative electrode tab1153disposed on the third negative electrode non-coating portion1123c.

The separator1140is made of an insulation material and is alternately stacked together with the positive electrode plate1110and the negative electrode plate1120. Here, the separator1140may be disposed between the positive electrode plate1110and the negative electrode plate1120and disposed on an outer surface of the positive electrode plate1110or the negative electrode plate1120.

The first positive electrode tab1151and the first negative electrode tab1161may be disposed so as not to overlap each other with respect to a direction in which the positive electrode1110and the negative electrode1120face each other. Here, the direction in which the positive electrode1110and the negative electrode1120face each other may be, for example, a lateral direction of a winding central axis. Also, ends of the first positive electrode tab1151and the first negative electrode tab1161may be spaced a predetermined distance from each other with respect to the direction parallel to the winding central axis so as not to overlap each other.

In the electrode assembly1100according to the fourth embodiment of the present invention, a positive electrode insulation tape may be further attached to the positive electrode non-coating portion1113to cover the positive electrode tab1150, and a negative electrode insulation tape may be further attached to the negative electrode non-coating portion1123to cover the negative electrode tab1160. Here, the positive electrode insulation tape and the negative electrode insulation tape may be attached in the same manner as that in which the positive electrode insulation tape170and the negative electrode insulation tape180of the electrode assembly100according to the foregoing first embodiment of the present invention are attached.

The positive electrode insulation tape may comprise a first positive electrode insulation tape attached to the first positive electrode non-coating portion1113ato cover the first positive electrode tab1151.

The negative electrode insulation tape may comprise a first negative electrode insulation tape attached to the first negative electrode non-coating portion1213ato cover the first negative electrode tab161, a second negative electrode insulation tape attached to the second negative electrode non-coating portion1123bto cover the second negative electrode tab1162, and a third negative electrode insulation tape attached to the third negative electrode non-coating portion1123cto cover the third negative electrode tab1163.

Also, each of the positive electrode insulation tape and the negative electrode insulation tape may comprise an electrical insulation material.

In the electrode assembly1100according to the fourth embodiment of the present invention, a lithium ion deposition prevention tape comprising an insulation material may be further attached to a portion of the positive electrode plate1110facing the first negative electrode insulation tape with the separator therebetween. Here, the lithium ion deposition prevention tape may be attached in the same manner as that in which the lithium ion deposition prevention tape190of the electrode assembly100according to the foregoing first embodiment of the present invention are attached. Here, the lithium ion deposition prevention tape may be disposed on a surface of the positive electrode active material portion1112of the positive electrode plate1110. Thus, the lithium ion deposition prevention tape1190may be disposed on a portion of the positive electrode plate1110facing the first negative electrode non-coating portion1123a, to which the first negative electrode insulation tape is attached, to prevent lithium ions, which are not exchanged, from being accumulated to be deposited during the charging and discharging.

Manufacturing Example

1-1 Manufacture of Electrode Assembly

A positive electrode non-coating portion was formed on each of two portions of a positive electrode sheet, which are spaced part from each other, to provide positive electrode tabs, and a negative electrode non-coating portion was formed on each of three portions of a negative electrode sheet, which are spaced apart from each other, to provide negative electrode tabs, thereby manufacturing an electrode assembly comprising the two positive electrode tabs and the three negative electrode tabs.

Here, a first positive electrode non-coating portion of the positive electrode non-coating portions disposed on the two portions of the positive electrode sheet and a first negative electrode non-coating portion formed between both side portions of the negative electrode sheet are formed at positions corresponding to each other.

1-2 Manufacture of Secondary Battery

The manufactured electrode assembly was accommodated together with an electrolyte in a battery case to manufacture a secondary battery.

Comparative Example

A secondary battery was manufactured in the same manner as that of the manufacturing example except that a positive electrode non-coating portion was formed on each of two portions of a positive electrode sheet, which are spaced part from each other, to provide positive electrode tabs, and a negative electrode non-coating portion was formed on each of two portions of a negative electrode sheet, which are spaced apart from each other, to provide negative electrode tabs, thereby manufacturing an electrode assembly comprising the two positive electrode tabs and the two negative electrode tabs. Here, according to the comparative example, the negative electrode non-coating portion may be formed on the two portions of the negative electrode sheet, and thus, the first negative electrode non-coating portion formed between both side portions of the negative electrode sheet according to the manufacturing example was not formed.

Experimental Example

Electricity was applied to the secondary battery to measure an effect of improving resistance.

As a result of measuring alternating current (AC) resistance, it was observed that the resistance value measured in the manufacturing example was reduced by about 20% when compared to that measured in the comparative example.

As a result, it may be seen that the resistance is significantly improved in the manufacturing example.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the electrode assembly and the secondary battery comprising the same according to the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Furthermore, the scope of protection of the present invention will be clarified by the appended claims.