Electrode assembly for secondary battery and lithium secondary battery including same

Abstract

The present invention relates to an electrode assembly for a secondary battery. The electrode assembly has a structure in which a laminate including a sheet-type positive electrode, a sheet-type negative electrode, and a sheet-type separator between the sheet-type positive electrode and the sheet-type negative electrode is wound, and an electron conductive tape is attached to an outer surface of the sheet-type negative electrode, which does not face the sheet-type positive electrode, in a width direction of the sheet-type negative electrode perpendicular to the winding direction of the laminate at a portion corresponding to the winding end portion of the sheet-type positive electrode.

Description

Electrode assembly for secondary battery, and lithium secondary battery including same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0108378, filed August 18, 2023, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to an electrode assembly for a secondary battery and a lithium secondary battery including the same.

[0004] As technological developments and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are attracting significant attention not only as an energy source for mobile devices such as cell phones, digital cameras, laptops, and wearable devices, but also as a power source for powertrains such as electric bicycles, electric cars, and hybrid electric vehicles.

[0005] Secondary batteries are classified into cylindrical batteries, in which the electrode assembly is housed in a cylindrical metal can, square batteries, in which the electrode assembly is housed in a square metal can, and pouch batteries, in which the electrode assembly is housed in a pouch-shaped case made of aluminum laminate sheet, depending on the shape of the battery case. Among these, cylindrical batteries have the advantages of relatively large capacity and structural stability.

[0006] The electrode assembly built into the battery case is a rechargeable power plant having a stacked structure of a positive electrode, a separator, and a negative electrode, and is classified into a jelly roll type, a stack type, and a stack / folding type. The jelly roll type is a form in which a separator is interposed between long sheet-shaped positive and negative electrodes coated with an active material and wound, and the stack type is a form in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked with a separator interposed between them, and the stack / folding type is a composite structure of the jelly roll type and the stack type. Among them, the jelly roll type electrode assembly has the advantages of being easy to manufacture and having a high energy density per weight.

[0007] However, recently, as the need for high capacity increases, the loading of the positive electrode increases, which increases the brittleness of the positive electrode, and as a result, the strength of the positive electrode end increases, and as charging and discharging proceed, the force applied to the negative electrode corresponding to the positive electrode end increases, causing the problem of the negative electrode breaking.

[0008] However, when the negative electrode is disconnected, a phenomenon is observed in which the electrical connection is disconnected in a 1+1 tab structure, i.e., when both the positive and negative electrodes have a 1 tab structure, and thus the operation of the lithium secondary battery, which has not reached the end of its life, is terminated.

[0009] Therefore, there is a need to develop lithium secondary battery technology that can solve these problems.

[0010] Accordingly, the purpose of the present invention is to provide an electrode assembly for a secondary battery, which can delay disconnection of a negative electrode portion corresponding to a positive electrode end in an electrode assembly of a coiled structure according to charging and discharging of the secondary battery.

[0011] The present invention also aims to provide an electrode assembly for a secondary battery in which the operation of the secondary battery does not end even if the negative electrode is disconnected by the positive electrode end during charging and discharging of the secondary battery.

[0012] According to one embodiment of the present invention, as an electrode assembly for a secondary battery,

[0013] A laminate having a rolled structure including a sheet-shaped positive electrode, a sheet-shaped negative electrode, and a sheet-shaped separator interposed between the sheet-shaped positive electrode and the sheet-shaped negative electrode,

[0014] An electrode assembly is provided in which an electron conductive tape is attached to the outer surface of the sheet-shaped negative electrode, which does not face the sheet-shaped positive electrode, in a width direction of the sheet-shaped negative electrode that is perpendicular to the winding direction of the laminate, at a portion corresponding to the winding end of the sheet-shaped positive electrode.

[0015] The above electronic conductive tape has a resistance of 0.01Ω / cm. 2 Within 100Ω / cm 2 It can be, and can have elasticity.

[0016] Specifically, the electronically conductive tape may have a structure in which an electronically conductive adhesive layer is formed on a substrate, and in detail, the electronically conductive adhesive layer may be a one-sided tape or a double-sided tape formed on one or both sides of the substrate.

[0017] At this time, the electronically conductive adhesive layer may contain a carbon material for electronic conductivity.

[0018] Such electronically conductive tape may be, for example, a carbon tape.

[0019] Specifically, the above-mentioned electronic conductive tape may be attached in the width direction of the sheet-shaped negative electrode at a portion corresponding to the winding end of the sheet-shaped positive electrode on the outer surface of the sheet-shaped negative electrode, and in detail, may be attached with an extended width of 0.5 mm to 35 mm on both sides based on the winding end edge of the sheet-shaped positive electrode.

[0020] Meanwhile, the length of the sheet-shaped negative electrode in the winding direction may be longer than the length of the sheet-shaped positive electrode in the winding direction, and the electrode assembly may have a structure in which the sheet-shaped positive electrode is wound so as to be positioned on the inside.

[0021] In addition, the electrode assembly may be an electrode assembly having a 1+1 tab structure in which the sheet-shaped positive electrode includes one positive electrode tab and the sheet-shaped negative electrode includes one negative electrode tab.

[0022] At this time, the sheet-shaped positive electrode is a free edge positive electrode in which a positive electrode non-conductive portion on which a positive electrode active material layer is not formed is formed in the middle, and the positive electrode tab can be positioned on the positive electrode non-conductive portion.

[0023] In addition, the above sheet-shaped negative electrode may have a structure in which a negative electrode non-conductive portion on which a negative electrode active material layer is not formed is formed on one or both sides, and the negative electrode tab is positioned on the negative electrode non-conductive portion formed at the winding end.

[0024] Meanwhile, according to another embodiment of the present invention, the present invention also provides a lithium secondary battery including the electrode assembly.

[0025] Figure 1 is a cross-sectional view of a laminate before the electrode assembly is wound.

[0026] Figure 2 is a schematic diagram showing the inner surface of an electrode assembly in which the laminate of Figure 1 is partially rolled up.

[0027] Fig. 3 is a schematic diagram showing the outer surface of the electrode assembly in a partially rolled state of the laminate of Fig. 1.

[0028] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless specifically stated otherwise.

[0029] The terms "about," "substantially," and the like used throughout this specification are used in a sense of or near to the numerical values ​​when manufacturing and material tolerances inherent in the meanings referred to are presented, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that mention exact or absolute values ​​to aid understanding of this specification.

[0030] The terms “width,” “length,” and “width” used in this specification are based on the definitions in the specification.

[0031] Additionally, throughout the specification, when we say "in plan", we mean when the target portion is viewed from above, and when we say "in cross section", we mean when the target portion is viewed from the side in a cross-section cut vertically.

[0032]

[0033] Hereinafter, based on the above definitions, embodiments of the invention will be described in detail with reference to the drawings. However, to clearly explain the present invention, parts irrelevant to the description have been omitted, and identical or similar components are designated by the same reference numerals throughout the specification.

[0034] Furthermore, the sizes and thicknesses of each component shown in the drawings are arbitrarily indicated for convenience of explanation, and thus the present invention is not necessarily limited to the illustrated components. In the drawings, the thicknesses are enlarged to clearly represent various layers and regions. Furthermore, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0035] The drawings are provided as examples and are not intended to limit the invention, which is defined only by the scope of the claims set forth below.

[0036] According to one embodiment of the invention, as an electrode assembly for a secondary battery,

[0037] A laminate having a rolled structure including a sheet-shaped positive electrode, a sheet-shaped negative electrode, and a sheet-shaped separator interposed between the sheet-shaped positive electrode and the sheet-shaped negative electrode,

[0038] An electrode assembly is provided in which an electron conductive tape is attached to the outer surface of the sheet-shaped cathode, which does not face the sheet-shaped anode, in a portion corresponding to the winding end of the sheet-shaped anode, in the width direction of the sheet-shaped cathode perpendicular to the winding direction of the laminate.

[0039] Fig. 1 shows a cross-sectional view of a laminate before the electrode assembly is wound, Fig. 2 shows a schematic view of the inner surface of the electrode assembly in a partially wound state, and Fig. 3 shows a schematic view of the outer surface of the electrode assembly in a partially wound state.

[0040] Referring to FIGS. 1 to 3, the electrode assembly (100) has a structure in which a laminate (100') including a sheet-shaped positive electrode (110), a sheet-shaped negative electrode (120), and a sheet-shaped separator (130) interposed between the sheet-shaped positive electrode (110) and the sheet-shaped negative electrode (120) is wound.

[0041] Here, the length (l2) of the sheet-shaped cathode (120) in the winding direction may be longer than the length (l1) of the sheet-shaped anode (110) in the winding direction.

[0042] Additionally, it may be wound in the direction of the arrow so that the sheet-shaped positive electrode (110) is positioned on the inside.

[0043] Furthermore, the sheet-shaped positive electrode (110) may include one positive electrode tab (113), and the sheet-shaped negative electrode (120) may include one negative electrode tab (123).

[0044] Although not limited thereto, in the case of an electrode assembly having a 1+1 tab structure in which tabs are included in each electrode, if a short circuit occurs at the cathode terminal due to charging and discharging of the secondary battery, the operation of the secondary battery is stopped as the cathode tab is disconnected.

[0045] In this case, the loss is very large because the operation is stopped even before the secondary battery's lifespan is over.

[0046] Therefore, the electrode assembly according to the present invention can be more suitably applied in the case of a 1+1 tab structure as described above.

[0047] Of course, it can be effectively used in a 1+2 tab structure that includes two negative tabs, as it can prevent a sudden increase in resistance.

[0048] Meanwhile, the sheet-shaped positive electrode (110) may be a free-edge positive electrode having a structure in which a positive electrode holding portion (110a) in which a positive electrode active material layer (112) is formed on a positive electrode current collector (111) and a positive electrode non-conducting portion (110b) in which a positive electrode active material layer (112) is not formed, and the positive electrode non-conducting portion (110b) is formed between the positive electrode holding portions (110a) rather than at the ends, i.e. in the middle of the sheet-shaped positive electrode (110).

[0049] At this time, the positive electrode tab (113) may be positioned on the positive electrode non-conductive portion (110b). At this time, the positive electrode tab (113) may be attached to the positive electrode non-conductive portion (110b) using welding, adhesive tape, or conductive adhesive, or the current collector (111) may be manufactured to include the positive electrode tab (113), and the electrical connection is not limited as long as the positive electrode tab (113) is positioned on the positive electrode non-conductive portion (110b).

[0050] In addition, the drawing shows a structure in which the positive electrode tab (113) is positioned in a direction facing the sheet-shaped negative electrode (120), but this is not limited thereto.

[0051] Here, the positive electrode active material layer (112) is manufactured by applying, drying, and rolling a slurry containing the positive electrode active material onto the positive electrode current collector (111). Here, the slurry may further include a conductive agent, a binder, or a filler in addition to the positive electrode active material.

[0052] The positive electrode current collector may generally have a thickness of 3 to 500 μm. In addition, the positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. The current collector may also form fine unevenness on its surface to increase the adhesive strength of the positive electrode active material, and various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric are possible.

[0053] And, in the case of the above positive electrode active material, it may include a compound capable of reversible intercalation and deintercalation of lithium, specifically a lithium metal oxide containing one or more metals such as iron, cobalt, manganese, nickel, or aluminum and lithium.

[0054] Specifically, the lithium metal oxide is a lithium-manganese oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt oxide (e.g., LiCoO2, etc.), a lithium-nickel oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O2 (here, 0 <Y<1), LiMn 2-Z Ni Z O4 (where 0<Z<2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O2 (here, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2Mn Y2 O2 (here, 0 <Y2<1), LiMn 2-Z1 Co Z1 O4 (wherein, 0<Z1<2) etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O2(wherein, 0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li(Ni p1 Co q1 Mn r1 )O4 (wherein, 0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2) etc.), lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2 )O2 (wherein, M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r2 and s2 are atomic fractions of independent elements, respectively, 0<p2<1, 0<q2<1, 0<r2<1, 0<s2<1, p2+q2+r2+s2=1), etc.), or lithium iron phosphate (e.g., Li 1+a Fe 1-x M x (PO 4-b )X b (Here, M is at least one selected from Al, Mg, and Ti, X is at least one selected from F, S, and N, -0.5≤a≤+0.5, 0≤x≤0.5, 0≤b≤0.1), and any one or two or more compounds thereof may be included.

[0055] Among these, the positive electrode active material may include a lithium metal oxide including lithium and two or more metals selected from the group consisting of nickel, manganese, cobalt, and aluminum.

[0056] The conductive agent is a component for further improving the conductivity of the positive electrode active material. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive nanomaterials such as carbon nanofibers or carbon nanotubes; fluorinated carbon powder; conductive powder such as aluminum powder or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. can be used. Among these, the conductive agent can further lower the resistance of the lithium metal battery and improve the output characteristics, etc. by including a conductive nanomaterial such as carbon nanotubes or carbon nanofibers.

[0057] Typically, the conductive material may be included in an amount of 1 to 20 wt%, or 1 to 15 wt%, or 1 to 10 wt% based on the total weight of the positive electrode active material layer.

[0058] The binder optionally included in the above-described positive electrode active material layer is a component that assists in the bonding of the positive electrode active material and the conductive material, and in the bonding to the current collector. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, nitrile rubber, styrene-butadiene rubber, or fluororubber, and a mixture or copolymer of two or more selected from these may also be used.

[0059] Typically, the binder may be included in an amount of 1 to 20 wt%, or 1 to 15 wt%, or 1 to 10 wt% based on the total weight of the positive electrode active material layer.

[0060] In addition, the filler as the component for suppressing the expansion is not particularly limited as long as it can suppress the expansion of the electrode without causing a chemical change in the battery, and for example, an olefin polymer such as polyethylene or polypropylene; a fibrous material such as glass fiber or carbon fiber; etc. can be used.

[0061] Meanwhile, the sheet-shaped negative electrode (120) includes a negative electrode holding portion (120a) in which a negative electrode active material layer (122) is formed on a negative electrode current collector (121), and a negative electrode non-conductive portion (120b) in which a negative electrode active material layer (122) is not formed, and the negative electrode non-conductive portion (120b) can be formed on one side or both sides.

[0062] At this time, the negative electrode tab (123) may be positioned on the negative electrode non-coated portion (120b) located at the winding end among these negative electrode non-coated portions. At this time, the negative electrode tab (123) may be attached on the negative electrode non-coated portion (120b) using welding, adhesive tape, or conductive adhesive, or the current collector (121) may be manufactured to include the negative electrode tab (123), and the electrical connection is not limited as long as the negative electrode tab (123) is positioned on the negative electrode non-coated portion (120b).

[0063] In addition, the drawing shows a structure in which a cathode tab (123) is positioned in a direction facing a sheet-shaped anode (110), but this is not limited thereto.

[0064] Here, the negative electrode active material layer (122) is manufactured by applying, drying, and rolling a slurry containing the negative electrode active material onto the negative electrode current collector (121). Here, the slurry may further include a conductive material, binder, or filler, as described for the positive electrode, in addition to the negative electrode active material.

[0065] The above-described negative electrode current collector may generally have a thickness of 3 to 500 μm. In addition, the positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and may be, for example, one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper surface-treated with a dissimilar metal, stainless steel surface-treated with a dissimilar metal, and an aluminum-cadmium alloy. The negative electrode current collector may have fine unevenness on its surface to increase the adhesion of the positive electrode active material, and may have various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven fabric.

[0066] The above negative active material is at least one carbon-based material selected from the group consisting of graphite, amorphous hard carbon, low-crystalline soft carbon, carbon black, acetylene black, Ketjen black, super P, graphene, and fibrous carbon, Si-based material, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SiO, SiO2, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물; 리튬 티타늄 산화물 등을 포함할 수 있지만, 당업계에 알려진 것이라면 이들만으로 한정되는 것은 아니다.

[0067] The sheet-shaped separator (130) may be formed of, but is not limited to, a sheet, a multi-film, a microporous film, a woven fabric, or a non-woven fabric, such as an olefin polymer such as polyethylene or polypropylene, or glass fiber. The sheet-shaped separator may be a thin insulating film having high ion permeability and mechanical strength, and the pore diameter of the separator may generally be in the range of 0.01 to 10 ㎛, and the thickness may generally be in the range of 5 to 300 ㎛, but is not limited thereto.

[0068] In addition, the sheet-shaped separator may be integrated with the electrolyte and interposed between the sheet-shaped positive electrode and the sheet-shaped negative electrode in the form of an electrolyte membrane or electrolyte film. In this case, the electrolyte membrane or electrolyte film may be in the form of a polymer matrix containing the lithium salt and a non-aqueous organic solvent described above, and a well-known polymer-based solid electrolyte, etc. may be used as the polymer matrix. In this case, it may be a semi-solid battery used in combination with a liquid electrolyte injected during the manufacture of the secondary battery.

[0069] Meanwhile, such an electrode assembly (100) has a problem in that a short circuit occurs when the portion of the sheet-shaped cathode (120) facing the end of the sheet-shaped positive electrode (110) is continuously impacted by expansion due to charging and discharging of the sheet-shaped positive electrode (110) and is cut.

[0070] However, since the electrical connection of the negative tab (123) is terminated by this cutting, the operation of the secondary battery is stopped before the life of the secondary battery is over.

[0071] Accordingly, in order to prevent such problems, an electrode assembly (100) according to one embodiment of the present invention has an electron conductive tape (124) attached to the outer surface of a sheet-shaped negative electrode (120) that does not face a sheet-shaped positive electrode (110), in a portion corresponding to the winding end of the sheet-shaped positive electrode (110), in the direction of the width (w) of the sheet-shaped negative electrode (120) that is perpendicular to the winding direction of the laminate (100').

[0072] At this time, the electronic conductive tape (124) may be attached to the outer surface of the sheet-shaped cathode (120) with an extended width (d1, d2) of 0.5 mm to 35 mm on both sides based on the winding end edge of the sheet-shaped anode (110).

[0073] Specifically, the widths (d1, d2) on both sides based on the corners may be 1 mm to 30 mm, and more specifically, 5 mm to 20 mm.

[0074] If the width is formed too thinly beyond the above range, it is difficult to achieve the intended effect of the present invention, and if it is formed too thick, it may affect the negative electrode active material layer, which is not desirable.

[0075] In addition, in order to achieve the intended effect of the present invention, the electronic conductive tape (124) must exhibit electronic conductivity, and accordingly, the resistance of the electronic conductive tape (124) must be 0.01 Ω / cm. 2 100 Ω / cm 2 It can be, in detail, 0.1 Ω / cm 2 80 Ω / cm 2 It can be 5 Ω / cm, more specifically 2 30 Ω / cm 2 It could be.

[0076] If the resistance is too high beyond the above range, the effect intended by the present invention, that is, the effect of preventing the secondary battery from being stopped from operating by maintaining conductivity even if the sheet-shaped negative electrode (120) is cut, cannot be obtained, and it is difficult to manufacture a tape having a resistance lower than the above, which is not preferable.

[0077] In addition, such electronic conductive tape (124) may have elasticity, and such elasticity has the effect of delaying cutting and short-circuiting of the sheet-shaped cathode (120).

[0078] At this time, the electronic conductive tape (124) may have a structure in which an electronic conductive adhesive layer is formed on a substrate in order to have electronic conductivity, and in detail, the electronic conductive adhesive layer may be a one-sided tape or a double-sided tape formed on one or both sides of the substrate.

[0079] The above substrate is not limited to any material that can be used in a secondary battery, but may be, for example, a polymer substrate, specifically a polyolefin substrate, and more specifically, for example, polyethylene (PE) or polypropylene (PP).

[0080] Meanwhile, the adhesive layer may include an adhesive and a conductive material. Here, the adhesive may be a polymer material having adhesive properties, and may include, for example, one or more materials selected from the group consisting of polycarbonate (PC), polyacrylate (PA), rubber, and styrene.

[0081] In addition, the conductive material is not limited to a material having conductivity, but may be, for example, a carbon material or a metal or semi-metal material, and more specifically, a carbon material.

[0082] Most specifically, the electronically conductive tape may be a carbon tape.

[0083] By attaching the electronic conductive tape (124), the electrode assembly (100) of the present invention has the effect of delaying the occurrence of a short circuit at the sheet-shaped negative electrode (120) corresponding to the end of the sheet-shaped positive electrode (110), and furthermore, even if a short circuit occurs at the sheet-shaped negative electrode (120), electronic conductivity can be maintained, so that the operation of the secondary battery can be continued, thereby improving the lifespan of the secondary battery.

[0084] Therefore, according to another embodiment of the present invention, a lithium secondary battery including the electrode assembly is provided.

[0085] Here, the lithium secondary battery has a structure in which the electrode assembly and the lithium non-aqueous electrolyte are embedded in a battery case.

[0086] The above lithium non-aqueous electrolyte may include a non-aqueous organic solvent and a lithium salt.

[0087] The lithium salt included in the above lithium non-aqueous electrolyte is used as a medium for transferring ions within a secondary battery. The lithium salt is, for example, Li as a cation. + Including, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N- , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - It may include an anion selected from the group consisting of .

[0088] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiFSI (lithium bis(fluorosulfonyl) imide, LiN(SO2F)2), LiBETI (lithium bis(perfluoroethanesulfonyl) imide, LiN(SO2CF2CF3)2) and LiTFSI (lithium bis(trifluoromethanesulfonyl) imide, LiN(SO2CF3)2).

[0089] The concentration of the above lithium salt can be appropriately changed within a commonly usable range, and can be included in the electrolyte at a concentration of 0.5 M to 6 M, or a concentration of 1 M to 5 M.

[0090] Meanwhile, the type of non-aqueous organic solvent that can be included in the electrolyte is not particularly limited, and any organic solvent previously known to be applicable to electrolytes of lithium ion batteries, etc., can be used. Examples of such organic solvents include at least one selected from the group consisting of carbonate solvents, ether solvents, nitrile solvents, phosphate solvents, and sulfone solvents.

[0091] More specifically, as the carbonate solvent, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, methyl propyl carbonate, ethyl methyl carbonate, ethyl propyl carbonate or methyl (2,2,2-trifluoroethyl) carbonate can be used, and as the phosphate solvent, trimethyl phosphate, triethyl phosphate or 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphosphorane 2-oxide can be used.

[0092] In addition, as the ether solvent, dibutyl ether, tetraglyme, diglyme, dimethoxy ethane, or tetrahydrofuran derivatives such as 2-methyl tetrahydrofuran can be used, and as the nitrile solvent, succinonitrile, adiponitrile, sebaconitrile, acetonitrile, or propionitrile can be used. In addition, as the sulfone solvent, dimethyl sulfone, ethylmethyl sulfone, or sulforane can be used.

[0093] [Explanation of symbols]

[0094] 100: Electrode assembly,

[0095] 110: Sheet-shaped anode,

[0096] 120: Sheet-shaped cathode,

[0097] 130: Sheet-shaped separator,

[0098] 124: Electronic conductive tape.

[0099] The electrode assembly for a secondary battery according to the present invention has the effect of delaying the occurrence of a short circuit in the sheet-shaped negative electrode corresponding to the sheet-shaped positive electrode end by attaching an electronically conductive tape to the outer surface of the sheet-shaped negative electrode corresponding to the sheet-shaped positive electrode end.

[0100] In addition, the electrode assembly for a secondary battery according to the present invention can maintain electronic conductivity even if a short circuit occurs at the sheet-shaped negative electrode corresponding to the sheet-shaped positive electrode end, thereby enabling the secondary battery to continue to operate, thereby improving the lifespan of the secondary battery.

Claims

1. As an electrode assembly for a secondary battery, A laminate having a rolled structure including a sheet-shaped positive electrode, a sheet-shaped negative electrode, and a sheet-shaped separator interposed between the sheet-shaped positive electrode and the sheet-shaped negative electrode, An electrode assembly in which an electron conductive tape is attached to the outer surface of the sheet-shaped cathode that does not face the sheet-shaped anode in a width direction of the sheet-shaped cathode that is perpendicular to the winding direction of the laminate, at a portion corresponding to the winding end of the sheet-shaped anode.

2. In paragraph 1, The resistance of the above electronic conductive tape is 0.01 Ω / cm 2 100 Ω / cm 2 Electrode assembly.

3. In paragraph 1, The above electronic conductive tape is an electrode assembly having elasticity.

4. In paragraph 1, The above-mentioned electronic conductive tape is an electrode assembly having a structure in which an electronic conductive adhesive layer is formed on a substrate.

5. In paragraph 4, The above electronic conductive tape is an electrode assembly in which the electronic conductive adhesive layer is formed on one or both sides of the substrate.

6. In paragraph 4, An electrode assembly in which the above-mentioned electronic conductive adhesive layer contains a carbon material.

7. In paragraph 1, The above-mentioned electronic conductive tape is an electrode assembly which is a carbon tape.

8. In paragraph 1, An electrode assembly in which the above-mentioned electronic conductive tape is attached to the outer surface of the sheet-shaped negative electrode with an extended width of 0.5 mm to 35 mm on both sides based on the edge of the winding end of the sheet-shaped positive electrode.

9. In paragraph 1, An electrode assembly in which the length of the sheet-shaped cathode in the winding direction is longer than the length of the sheet-shaped anode in the winding direction.

10. In paragraph 1, The above electrode assembly is an electrode assembly having a structure in which the sheet-shaped positive electrode is wound so as to be positioned on the inside.

11. In paragraph 1, An electrode assembly wherein the sheet-shaped positive electrode includes one positive tab and the sheet-shaped negative electrode includes one negative tab.

12. In paragraph 11, The above sheet-shaped positive electrode is a free-edge positive electrode having a positive electrode non-conductive region formed in the middle where a positive electrode active material layer is not formed, and an electrode assembly in which the positive electrode tab is positioned on the positive electrode non-conductive region.

13. In paragraph 11, The above sheet-shaped negative electrode is an electrode assembly in which a negative electrode non-conductive portion on which a negative electrode active material layer is not formed is formed on one or both sides, and the negative electrode non-conductive portion is formed including a winding end.

14. In paragraph 13, An electrode assembly in which the negative electrode tab is positioned on the negative electrode non-conductive portion formed at the above winding end.

15. A lithium secondary battery comprising an electrode assembly according to any one of claims 1 to 14.

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