KR101869137B1 - Electrode Assembly Comprising Gas Discharging Passage and Manufacturing Method for the Same - Google Patents

Abstract

The present invention relates to an electrode assembly for a secondary battery comprising a cathode, a cathode, and a separator interposed between the anode and the cathode, wherein the anode is represented by the following Formula 1, and a lithium composite transition metal oxide, And a preformed gas discharge passage which is contained in the active material and communicates with the outside so that gas generated inside the electrode assembly can be discharged to the outside of the electrode assembly during charging and discharging of the electrode assembly, And a discharge passage portion of the structure that is converted into the gas discharge passage by the discharge passage portion, and a method of manufacturing the electrode assembly.
Li _{1 + a} Ni _b M _c Mn _{2- (a + b + c)} O _4-z (1)
Wherein M is one or more selected from the group consisting of Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and other transition metals, and 0? A? 0.1, 0.4? , 0? C? 0.1, and 0? Z? 0.1.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode assembly including a gas discharge passage,

The present invention relates to an electrode assembly including a gas discharge path and a method of manufacturing the same.

Due to the rapid increase in the use of fossil fuels, the demand for the use of alternative energy or clean energy is increasing. As a part of this, the most active field of research is electric power generation and storage.

At present, a typical example of an electrochemical device utilizing such electrochemical energy is a secondary battery, and the use area thereof is gradually increasing.

The secondary battery is classified into a cylindrical battery and a prismatic battery in which the electrode assembly is housed in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch-shaped battery in which the electrode assembly is housed in a pouch-shaped case of an aluminum laminate sheet .

In addition, the electrode assembly incorporated in the battery case is a charge / dischargeable power generation device composed of a lamination structure of a positive electrode / separator / negative electrode, and includes a jelly-roll type battery having a separator interposed between a positive electrode and a negative electrode coated with an active material, , And a plurality of positive electrodes and negative electrodes of a predetermined size are sequentially stacked in a state in which the separator is interposed therebetween. Among them, the jelly-roll type electrode assembly has an advantage of being easy to manufacture and having a high energy density per weight.

On the other hand, in lithium secondary batteries, lithium-containing cobalt oxide (LiCoO ₂ ) is mainly used as a cathode active material, and lithium-containing manganese oxides such as LiMnO _{2 having a} layered crystal structure and LiMn ₂ O _{4 having a} spinel crystal structure, Lithium-containing nickel oxide (LiNiO ₂ ) is also used.

Among the above cathode active materials, LiCoO ₂ has excellent properties such as excellent cycle characteristics and is widely used at present, but its safety is low and there is a problem that it is expensive due to the resource limit of cobalt as a raw material.

Lithium nickel oxide such as LiNiO ₂ exhibits a high discharge capacity when charged at 4.25 V at a lower cost than LiCoO ₂ , but has a high production cost, swelling due to gas generation in the battery, low chemical stability, high pH And so on.

In addition, lithium manganese oxides such as LiMnO ₂ and LiMn ₂ O ₄ have the advantage of using manganese which is rich in resources and environment-friendly as a raw material, and thus attracts much attention as a cathode active material that can replace LiCoO ₂ . Particularly, LiMn ₂ O ₄ has advantages such as relatively low cost and high output, but has a disadvantage that energy density is lower than LiCoO ₂ and ternary active materials.

In order to overcome this disadvantage, replacing a part of Mn with Ni in LiMn ₂ O ₄ has a higher operating voltage (about 4.7V or more) than the original operating voltage (about 4V). Spinel materials with a composition of LiNi _x Mn _2-x O ₄ (0.4 ≦ _x ≦ 0.6) have high operating voltages and are therefore suitable for use in electric vehicles (EV), which require high energy and high output performance, It is a material highly likely to be used as a cathode active material of a battery. However, due to the high charge / discharge voltage potential, dissolution of Mn and side reaction of the electrolyte occur in the cathode active material.

Particularly, the gas generated by the side reaction of the electrolyte forms a gas trap in the electrode assembly, thereby causing the electrode to be desorbed, thereby deteriorating the overall performance of the battery, .

Therefore, there is a high need for a technique capable of improving the lifetime characteristics of a battery while using a cathode active material exhibiting an operating voltage in a high voltage range as described above.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and have found that when the electrode assembly includes a gas discharge passage having a structure communicating with the outside or includes a discharge passage scheduled portion as described later, It has been confirmed that even if gas is generated in the electrode assembly due to the side reaction, generation of gas traps is suppressed, the overall performance of the battery can be maintained, and the life characteristics can be improved.

Accordingly, the electrode assembly for a secondary battery according to the present invention, comprising a cathode, a cathode, and a separator interposed between the anode and the cathode, is characterized in that the anode is represented by the following Chemical Formula 1 and has a lithium complex transition metal And a preformed gas discharge passage communicating with the outside so that the gas generated inside the electrode assembly may be discharged to the outside of the electrode assembly during charging and discharging of the electrode assembly, And a gas discharge passage scheduled to be converted into the gas discharge passage by the gas that has been discharged.

Li _{1 + a} Ni _b M _c Mn _{2- (a + b + c)} O _4-z (1)

Wherein M is one or more selected from the group consisting of Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and other transition metals, and 0? A? 0.1, 0.4? , 0? C? 0.1, and 0? Z? 0.1.

When a positive electrode active material containing a high Mn content as shown in Formula 1 and exhibiting an operating voltage in a voltage range of 5 V is used, the capacity is severely decreased as the charge / discharge cycle progresses, and the life characteristic is rapidly deteriorated have.

According to the present invention, this problem is the main cause of gas trap generation in the electrode assembly. Specifically, in the case of a secondary battery operating at a high voltage, since the oxidation potential of the electrolyte is reached at the time of activation or charge / discharge, decomposition of the electrolyte becomes more active at this time. The gas due to the decomposition of the electrolytic solution can not be discharged from the inside of the electrode assembly to the outside, thereby forming a gas trap. Therefore, lithium ions can not be exchanged between the active materials, resulting in a capacity reduction by the corresponding volume.

The decomposition of the electrolytic solution is continuously generated in the charging / discharging process, which causes the generation of gas traps to be increased. As a result, the life characteristics of the battery deteriorate rapidly.

The electrode assembly according to the present invention includes a pre-formed gas discharge passage communicating with the outside so that gas generated inside the electrode assembly can be discharged to the outside of the electrode assembly during charging and discharging, Even if gas is generated in the electrode assembly including the discharge passage scheduled portion of the structure that is converted into the passage, it is discharged to the outside of the electrode assembly through the gas discharge passage, so that generation of gas trap can be suppressed.

Such an electrode assembly suppresses the generation of gas traps therein, so that even if charging and discharging are repeated, the capacity reduction of the battery is not so large, and as a result, the life characteristics of the battery are improved.

In one specific example, the 5V voltage range in which the lithium composite transition metal oxide exhibits the operating voltage may be in the range of 4.5V to 5.5V, in particular in the range of 4.5V to 5.0V, May range from 4.7V to 4.9V. This range is only one example, and it can be considered that the voltage range in which the decomposition reaction occurs actively is included in the 5V voltage range of the present invention when the operating voltage reaches the oxidation potential of the electrolyte solution.

The position of the pre-formed gas discharge passage is not particularly limited as long as gas can be discharged to the outside of the electrode assembly to suppress the formation of gas traps. However, for example, the position between the current collector and the electrode mixture layer and / And the electrode mixture layer.

Specifically, the pre-formed gas discharge passage may be located at least between the separator and the cathode mixture layer. According to the present invention, since the generation frequency of the gas trap is highest between the separator and the cathode mixture layer in the electrode assembly, The generation of the gas trap can be most effectively suppressed by placing the gas discharge passage in the gas discharge passage.

In one specific example, the pre-formed gas discharge passage may be one or more gas discharge grooves formed on at least one side of the electrode mix layer, and more particularly, the depth of indentation of the gas discharge groove To 5% to 50%, and more specifically from 5% to 40%.

If the depth of indentation of the gas discharge groove is less than 5% based on the thickness of the electrode mixture layer, it is difficult to smoothly discharge the gas generated inside the electrode assembly, so that the effect of suppressing the generation of gas trap may not be large, The loading amount of the electrode active material may be reduced due to the volume occupied by the gas discharge groove, and the capacity of the battery may be lowered.

Meanwhile, the discharge passage scheduled portion may be a structure that is converted into a gas discharge passage only when the gas is discharged.

Specifically, the discharge passage scheduled portion may have a structure in which the electrode mix layer and the separation membrane are formed in a portion where the electrode mixture is adhered with a relatively low coupling force.

More specifically, the discharge passage scheduled portion is formed between the electrode mixture layer and the separator, and the electrode assembly layer and the separator have a relatively strong bonding force between the electrode assembly layer and the separator, And a structure in which the second joint is released from the gas inside the electrode assembly and is converted into the gas discharge passage.

Although forming the gas discharge path in the process of manufacturing the electrode assembly may be preferable from the viewpoint of reliability of the passage securing, it is necessary to change the existing manufacturing process so as to maintain the pre-formed gas discharge path, . However, if the discharging path portion is formed instead of the gas discharging path, the manufacturing process of the electrode assembly can be relatively simplified and the loading amount of the electrode active material can be relatively increased, which is advantageous in terms of securing the capacity of the battery.

In one specific example, the pre-formed gas discharge passageway or discharge passageway presumably may be one or more strip structures in plan view.

Specifically, the width of the strip structure may be 20% to 2000%, and more particularly, 50% to 1000% based on the thickness of the electrode mixture layer.

When the width of the strip structure is less than 20% based on the thickness of the electrode material mixture layer, it is difficult to smoothly discharge the gas generated in the electrode assembly, so that the effect of suppressing gas trap generation may not be significant. The amount of loading of the electrode active material may be reduced due to the volume occupied by the gas discharge passage or the adhesive force between the electrode mixture layer and the current collector or separator may be lowered so that the efficiency of manufacturing the electrode assembly may be deteriorated.

In yet another example, the pre-formed gas discharge passage or discharge passage predeterminable portion may be net-like in plan view.

If the gas discharging passage or the discharge passage predetermined portion is formed in a net structure, the length of the passage through the inside of the electrode assembly from each point to the outside is reduced, so that generation of the gas trap can be suppressed more effectively.

The pre-formed gas discharge passage or discharge passage predeterminable portion may be formed in a lamination process, though it is not particularly limited. In the case where the pre-formed gas discharge passage or the discharge passage preform is formed before the lamination process, such a passage structure may be deformed through lamination.

In one specific example, the negative electrode is made of non-graphitized carbon, graphitized carbon, graphite carbon, Li _x Fe ₂ O ₃ (0? _X? 1), Li _x WO ₂ (0? , Sn _x Me _1-x Me _y O _z (Me: Mn, Fe, Pb, Ge; Me ': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , SnO ₂ , Pb ₂ O ₃ , SnO ₂ , _{Pb 3 O 4, Sb 2 O} 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, Bi 2 O 5, metal oxide, a polyacetylene conductive polymer; Li-Co-Ni-based material, titanium oxide, lithium metal oxide represented by the following formula (2), and the like.

Li _a M ' _b O _{4-ca c} (2)

In the above formula, M 'is at least one element selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al and Zr; a and b are 0.1? a? 4; Is determined according to the oxidation number of M 'in the range of 0.2? B? 4; c is determined according to the oxidation number in the range of 0? c <0.2; A is one or more of an anion of -1 or -2.

Specifically, the lithium metal oxide represented by the above formula (2) may be lithium titanium oxide (LTO) represented by the following formula (3), specifically Li _0.8 Ti _2.2 O ₄ , Li _2.67 Ti _1.33 O ₄ , LiTi ₂ O ₄ , Li _1.33 Ti _1.67 O ₄ , Li _1.14 Ti _1.71 O _{4, and the} like, but there is no particular limitation on the composition and kind of lithium ions capable of intercalating / deintercalating lithium ions, and more specifically, And has a spinel structure Li _1.33 Ti _1.67 O ₄ or LiTi ₂ O ₄ having excellent reversibility.

Li _a Ti _b O ₄ (3)

In the above formula, 0.5? A? 3, 1? B? 2.5.

When a lithium composite transition metal oxide having a relatively high spinel structure is used as a cathode active material, the LTO having a high electric potential can be used as an anode active material to improve a rate characteristic, and Li plating Can be prevented.

The lithium complex transition metal oxide of Formula 1 may be a lithium nickel manganese oxide represented by Formula 4 below.

LiNi _x Mn _2-x O ₄ (4)

In the above formula, 0.4? X? 0.6.

Hereinafter, other components of the electrode assembly will be described.

The anode is prepared by applying a mixture of a cathode active material, a conductive material and a binder on a cathode current collector, followed by drying and pressing. If necessary, a filler may be further added to the mixture.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component which assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

On the other hand, the negative electrode is manufactured by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

The negative electrode current collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The structure of the electrode assembly is not particularly limited as long as it is a structure capable of generating a gas trap upon charging and discharging. For example, when a plurality of positive electrodes and negative electrodes cut in a predetermined size unit are sequentially (Stacked type) electrode assembly in which a positive electrode and a negative electrode are laminated in a stacked state with a separator interposed therebetween, or a stacked-folded electrode having a structure in which a bi- Assembly or the like.

The present invention also provides a secondary battery in which the electrode assembly is sealed inside a battery case together with an electrolyte solution.

The secondary battery may be a prismatic secondary battery in which an electrode assembly is embedded in a square metal can, or a pouch type secondary battery in which an electrode assembly is embedded in a case of a laminate sheet including a resin layer and a metal layer.

The laminate sheet may be an aluminum laminate sheet. Specifically, a resin outer layer having excellent durability is added to one surface (outer surface) of the metal barrier layer, and a thermally fusible resin sealant layer is provided on the other surface Structure.

Since the resin outer layer has excellent resistance from the external environment, it is necessary to have a tensile strength and weather resistance of a predetermined level or higher. In this respect, polyethylene terephthalate (PET) and stretched nylon film can be preferably used as the polymer resin of the resin outer layer.

The metal barrier layer may include aluminum or aluminum alloy so as to exhibit a function of improving the strength of the battery case, in addition to a function of preventing foreign matter such as gas or moisture from leaking or leaking.

As the polymer resin of the resin sealant layer, a polyolefin resin having a low heat absorbing property (heat adhesion property) and low hygroscopicity in order to suppress penetration of an electrolyte solution and not being swollen or eroded by an electrolytic solution is preferably used And more particularly, lead-free polypropylene (CPP) may be used.

In general, a polyolefin resin such as polypropylene has a low adhesive force with a metal. Therefore, as a method for improving the adhesion with the metal barrier layer, more specifically, an adhesive layer is additionally provided between the metal layer and the resin sealant layer, And blocking characteristics can be improved. Examples of the material of the adhesive layer include a urethane-based material, an acryl-based material, a composition containing a thermoplastic elastomer, and the like, but are not limited thereto.

The electrolytic solution contains a lithium salt, and examples of the electrolytic solution include non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer containing an ionic dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

In some cases, for the purpose of improving the charge-discharge characteristics and flame retardancy of the electrolytic solution, it is possible to use, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, May be added. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

The present invention also provides a battery pack including the secondary battery as a unit cell, and a device including the battery pack as a power source.

The device may be, for example, a computer, a mobile phone, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle, a plug- Or a system for power storage, but it is not limited to these.

Since the structure and manufacturing method of such a device are well known in the art, a detailed description thereof will be omitted herein.

The present invention also provides a method of manufacturing the electrode assembly for a secondary battery.

In one specific example,

(a) preparing a positive electrode, a negative electrode, and a separator comprising the lithium composite transition metal oxide represented by Formula 1 as a positive electrode active material;

(b) forming at least one groove structure on at least one surface of the anode and the cathode facing the separator;

(c) stacking the separator so that the separator is positioned between the anode and the cathode; And

(d) a lamination process of joining the lamination structure of the anode, the cathode and the separator to form a gas discharge passage with the groove structure being maintained.

More specifically, in the step (d), only the pressure is applied without applying heat, and the pressure is not applied to the portion corresponding to the groove structure upon application of pressure.

At this time, the pressure may be in the range of 2 to 10 bar, and if it is less than 2 bar, it is difficult to obtain a sufficient bonding force between the anode, the cathode and the separator, and if it exceeds 10 bar, It is not preferable.

Although this manufacturing method may be advantageous from the viewpoint of reliability of securing the gas discharge path, it may be difficult to maintain the pre-formed gas discharge path in the manufacturing process. Therefore, in another specific example for preventing this, How to do it,

(a) preparing a positive electrode, a negative electrode, and a separator comprising the lithium composite transition metal oxide represented by Formula 1 as a positive electrode active material;

(b) depositing a separator between the anode and the cathode; And

(c) a lamination structure for joining the stacked structure of the positive electrode, the negative electrode and the separation membrane to each other by applying a relatively small pressure to a portion corresponding to the gas discharge passage or the discharge passage preliminary portion to form a gas discharge passage, Process.

In this case, applying a relatively small pressure includes not applying pressure.

In one example, in the step (c), by using a pressing member having one or more strip-shaped projections formed on the surface facing the electrode assembly so that the gas discharge passage or the discharge passage projecting portion of the strip structure can be formed, However, this is only one concrete example, and the specific shape and number of the pressing members are not limited.

In another example, the pressing member including two or more polygonal or circular protrusions on the surface facing the electrode assembly may be laminated to form a gas discharge passage or a discharge passage forming portion of the net structure in the process (c) You may.

In addition, in order to form the gas discharge passage or the discharge passage predetermined portion in the strip structure or the net structure in the process (c), the cylindrical pressure roller including at least one protrusion on the outer surface facing the electrode assembly is laminated It is possible.

As described above, the electrode assembly according to the present invention includes a gas discharge passage having a structure communicating with the outside of the electrode assembly, or includes a discharge outlet portion, and gas is generated inside the electrode assembly due to a side reaction of the electrolyte solution The generation of gas traps can be suppressed, the overall performance of the battery can be maintained, and the life characteristics can be improved.

1 is a vertical cross-sectional view schematically showing a general electrode assembly;
2 is a vertical sectional view schematically showing an electrode assembly according to one embodiment of the present invention;
3 is a plan view schematically showing an anode included in the electrode assembly of FIG. 2;
4 and 5 are plan views schematically showing an anode included in an electrode assembly according to another embodiment of the present invention;
6 and 7 are schematic views illustrating a method of manufacturing an electrode assembly according to an embodiment of the present invention;
8 is a schematic view of a method of manufacturing an electrode assembly according to another embodiment of the present invention;
9 and 10 are perspective views schematically showing a pressing member used in a method of manufacturing an electrode assembly according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

1 is a schematic vertical cross-sectional view of a typical electrode assembly.

Referring to FIG. 1, an electrode assembly 100 includes an anode 110, a cathode 120, and a separator 130.

Specifically, the separator 130 is interposed between the anode 110 and the cathode 120, the anode 110 has the smallest area, the separator 130 has the largest area, and the cathode 120 Is narrower than the anode 110 and narrower than the separator 130.

The positive electrode 110 is composed of a positive electrode collector 111 and a positive electrode mixture layer 113 and is a cross section electrode having a positive electrode mixture layer 113 formed on only one side of the positive electrode collector 111.

The cathode 120 is also made of a cathode current collector 121 and a cathode mixture layer 123 and is a cross section electrode in which a cathode mixture layer 123 is formed on only one side of the anode current collector 121.

One surface of the separator 130 faces the positive electrode mixture layer 113 and the other side thereof is stacked so as to face the negative electrode mixture layer 123.

2 is a schematic vertical cross-sectional view of an electrode assembly according to an embodiment of the present invention.

Referring to FIG. 2, the electrode assembly 200 includes an anode 210, a cathode 220, and a separator 230.

The electrode assembly 200 is generally similar to the electrode assembly 100 of Figure 1. More specifically, the separator 230 is interposed between the anode 210 and the cathode 220, The area of the separator 230 is the largest and the area of the cathode 220 is larger than that of the anode 210 and narrower than the separator 230.

The positive electrode 210 is composed of a positive electrode collector 211 and a positive electrode mixture layer 213 and is a cross section electrode having a positive electrode mixture layer 213 formed on only one side of the positive electrode collector 211.

The cathode 220 is also composed of a cathode current collector 221 and a cathode mixture layer 223 and is a cross section electrode in which a cathode mixture layer 223 is formed on only one side of the anode current collector 221.

2, the electrode assembly 200 according to the present invention is provided with an electrode assembly 200 having a structure in which gas generated inside the electrode assembly 200 is discharged to the outside of the electrode assembly 200 during charging / And discharge passages 301, 302, 303, and 304 are formed.

The number, position, width, depth, and spacing of the gas discharge passages 301, 302, 303, and 304 are determined by the number of the gas discharge passages 301, 302, And the degree of generation of gas.

Specifically, three gas discharge passages 301 are formed between the cathode current collector 211 and the cathode mixture layer 213, and three gas discharge passages 301 are formed between the cathode mixture layer 213 and the separator 230. [ Are formed.

Three gas discharge passages 303 are formed between the separator 230 and the negative electrode mixture layer 223 and three gas discharge passages 303 are formed between the negative electrode collector 221 and the negative electrode mixture layer 223, (Not shown).

The gas discharge passages 301 and the gas discharge passages 302 are arranged in parallel to each other in the stacking direction with respect to the stacking direction while the gas discharge passages 303 and the gas discharge passages 304 are arranged on the basis of the stacking direction The top and bottom are offset.

The indentation depths of the gas discharge passages 301, 302, 303 and 304 are about 30% based on the thickness of the electrode mixture layers 213 and 223.

3 is a plan view schematically showing the anode included in the electrode assembly of FIG.

3, an anode 210 has a positive electrode mixture layer 213 formed on one surface of a current collector, and an electrode tab 212 protrudes from an upper end of the current collector.

Three gas discharge passages 311, 312, and 313 are formed in the positive electrode mixture layer 213 and the gas discharge passages 311, 312, and 313 form a strip structure in a planar shape in the lateral direction.

FIGS. 4 and 5 schematically show plan views of an anode included in an electrode assembly according to another embodiment of the present invention, respectively.

4, the anode 210a is configured to be generally similar to the anode 210, but the anode 210a is different from the anode 210 in that the anode mixture layer 213 has two gases There is a difference in that the discharge passages 314 and 315 are formed and the gas discharge passages 314 and 315 form a strip structure in a planar shape in the longitudinal direction.

5, the anode 210b is configured to be generally similar to the anode 210, but the anode 210b is different from the anode 210 in that the cathode mix layer 213 has five gases The three gas discharge passages 311, 312, and 313 form a strip structure in a planar shape in the transverse direction, and two gas discharge passages 311, 312, 313, and 315 are formed. The passages 314 and 315 form a strip structure in a planar shape in the longitudinal direction, so that the gas discharge passages generally form a net structure in a plan view.

6 and 7 schematically show a method of manufacturing an electrode assembly according to an embodiment of the present invention.

Referring to FIG. 6, a process of forming three groove structures 320 in a positive electrode mixture layer of an anode 210 using a pressure roller 410 is shown.

Three protrusions 411 are formed on the outer surface of the pressing roller 410 facing the anode 210. The recesses 412 are formed on the protrusions 411 and the protrusions 411 are formed on the protrusions 411, The width is relatively narrow compared to the width of the indentations 412.

The outer surface of the pressure roller 410 is faced to the positive electrode mixture layer of the anode 210 and rotated and pressed counterclockwise to form a groove 320 structure in the region of the positive electrode mixture layer facing the recessed portions 411 .

Referring to FIG. 7, a lamination process of forming a gas discharge path by joining a lamination structure of an anode, a cathode, and a separator in a state in which the groove 320 structure is maintained is schematically shown.

The pressure roller 420 is rotated counterclockwise so that the outer surface of the pressure roller 420 is positioned on the laminated structure 201 in which the positive electrode, the negative electrode and the separator are laminated while the groove 320 structure is maintained, To laminate.

At this time, the pressure roller 420 is composed of three indentations 422 facing the three grooves 320 and protruding portions 421 facing the other portions, and the width of the indentations 422 is larger than the width 421 are relatively narrow compared to the width.

The pressure may not be applied to the portion corresponding to the groove 320 structure during the lamination process of the laminate structure 201 by the indentations 422. Accordingly, even after the lamination, the groove 320 structure is formed, . In order to more effectively maintain the structure of the groove 320, lamination is performed by applying only pressure without applying heat in the lamination process.

On the other hand, pressure is applied to the portion of the laminated structure 201 facing the protruding portion 421 to form the joint portion 250.

FIG. 8 schematically shows a method of manufacturing an electrode assembly according to another embodiment of the present invention.

Referring to FIG. 8 in comparison with FIG. 7, FIG. 8 schematically shows a lamination process of forming the discharge passage protector 330 by joining the lamination structure 201a of the anode, the cathode, and the separation membrane.

The groove 320 structure is already formed in the laminate structure 201 of FIG. 7 and is maintained to form the gas discharge passage. On the other hand, the laminate structure 201a of FIG. 8 is not formed with a groove structure, There is a difference in that the joint portion 250 and the discharge passage protector 330 are formed.

The pressing roller 420a is composed of three indentations 422 and three protrusions 421 so as to form three outlet channels and the width of the indentations 422 is larger than the width of the protrusions 422. [ 421 are relatively narrow.

A discharge passage protector 330 having a relatively weak coupling force between the electrode mixture layer and the separator is formed in the lamination structure 201 facing the recessed portion 422 and a portion facing the protrusion portion 421 A bonding portion 250 having a relatively strong bonding force is formed.

When gas is generated inside the electrode assembly during charging / discharging of the electrode assembly, the discharge passage protector 330 releases the separation of the separator and the electrode mixture layer at the discharge passage protector 330 and is converted into the gas discharge passage.

9 and 10 are a schematic perspective view of a pressing member used in manufacturing an electrode assembly according to another embodiment of the present invention, respectively.

9, the pressing member 430 includes four protrusions 431 and three indentations 432 on the upper surface which faces the electrode assembly, so that the gas discharge passage or the discharge passage protruding portion of the strip structure can be formed. Is formed.

The area of the upper surface of the pressing member 430 corresponds to the area of the electrode assembly. The protrusions 431 and the indentations 432 are alternately arranged in strip form.

A gas discharge passage or a discharge passage predetermined portion is formed at a portion of the electrode assembly facing the depression portion 432 of the pressing member 430 and a bonding portion is formed at a portion of the electrode assembly facing the projection portion 431.

10, the pressing member 440 has twelve rectangular protrusions 441 formed on the upper surface, which is a surface facing the electrode assembly, so as to form a gas discharging passage or discharging passage forming portion having a net structure, Three indentations 442 and two indentations 443 in the transverse direction are formed.

The recessed portions 442 in the longitudinal direction and the recessed portions 443 in the transverse direction intersect with each other to form a net structure and the gas discharge passage or the gas discharge passage is formed in a portion of the electrode assembly facing the recessed portion 432 of the pressing member 440 And a joint portion is formed at a portion of the electrode assembly facing the projecting portion 441. [

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Claims (27)

An electrode assembly for a secondary battery comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
Wherein the anode comprises a lithium complex transition metal oxide represented by the following Chemical Formula 1 and exhibiting an operating voltage in a 5V voltage region as a cathode active material,
And a gas discharge path communicating with the outside so that gas generated inside the electrode assembly can be discharged to the outside of the electrode assembly during charging and discharging of the electrode assembly ,
Wherein the gas discharge passage is one or more gas discharge grooves formed on at least one surface of the electrode mix layer,
Wherein the recessed depth of the gas discharge groove is 5% to 50% based on the thickness of the electrode mixture layer,
(a) preparing a cathode, a cathode, and a separator comprising a lithium complex transition metal oxide represented by Chemical Formula 1 as a cathode active material;
(b) forming at least one groove structure on at least one surface of the anode and the cathode facing the separator;
(c) stacking the separator so that the separator is positioned between the anode and the cathode; And
(d) a lamination process of joining a lamination structure of an anode, a cathode and a separator to form a gas discharge passage with the groove structure maintained,
In the step (d), only the pressure is applied without applying heat and the lamination is performed. When pressure is applied, no pressure is applied to the portion corresponding to the groove structure,
Wherein the pressure is in the range of 2 to 10 bar.
Li _{1 + a} Ni _b M _c Mn _{2- (a + b + c)} O _4-z (1)
Wherein M is one or more selected from the group consisting of Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and other transition metals, and 0? A? 0.1, 0.4? , 0? C? 0.1, and 0? Z? 0.1. An electrode assembly for a secondary battery comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
Wherein the anode comprises a lithium complex transition metal oxide represented by the following Chemical Formula 1 and exhibiting an operating voltage in a 5V voltage region as a cathode active material,
And a discharge passage portion that is configured to be converted into a gas discharge passage by a gas generated therein so that gas generated inside the electrode assembly can be discharged to the outside of the electrode assembly during charging and discharging of the electrode assembly. As a result,
(a) preparing a cathode, a cathode, and a separator comprising a lithium complex transition metal oxide represented by Chemical Formula 1 as a cathode active material;
(b) depositing a separator between the anode and the cathode; And
(c) In bonding the laminated structure of the positive electrode, the negative electrode and the separator, a pressure lower than a pressure for bonding the laminated structure of the positive electrode, the negative electrode and the separator is applied to a portion corresponding to the discharge passage pre- A lamination process for forming a predetermined passage portion; / RTI &gt;
Wherein the lamination is performed using a pressing member having one or more strip-shaped protrusions formed on a surface facing the electrode assembly so that the discharging passage forming portion can be formed in the step (c)
Li _{1 + a} Ni _b M _c Mn _{2- (a + b + c)} O _4-z (1)
Wherein M is one or more selected from the group consisting of Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and other transition metals, and 0? A? 0.1, 0.4? , 0? C? 0.1, and 0? Z? 0.1. The method of claim 1 or claim 2, wherein the negative electrode is a negative electrode active material, graphitizing carbon, graphitizing softening carbon, graphite based _{carbon, Li x Fe 2 O 3 (} 0≤x≤1), Li x WO 2 (0≤ x, _{y, z, z, and z in the} periodic table, Sn _x Me _1-x Me _y O _z (Me: Mn, Fe, Pb, Ge; Me ' A metal alloy oxide, a lithium metal, a lithium alloy, a silicon-based alloy, a tin-based alloy, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO ₂ , GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , Bi ₂ O ₅ , Polymer; Li-Co-Ni-based materials, titanium oxide, and to method of manufacturing an electrode assembly comprising at least one selected from the group consisting of lithium metal oxide represented by General Formula 2:
Li _a M ' _b O _{4-ca c} (2)
In the above formula, M 'is at least one element selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al and Zr;
a and b are 0.1? a? 4; Is determined according to the oxidation number of M 'in the range of 0.2? B? 4;
c is determined according to the oxidation number in the range of 0? c <0.2;
A is one or more of an anion of -1 or -2. The method of claim 3, wherein the lithium metal oxide represented by Formula 2 is Lithium Titanium Oxide (LTO) represented by Formula 3 :
Li _a Ti _b O ₄ (3)
In the above formula, 0.5? A? 3, 1? B? 2.5. According to claim 1 or 2, wherein the lithium composite transition metal oxide of Formula 1 has the following method for manufacturing an electrode assembly, it characterized in that the lithium-nickel-manganese oxide represented by the general formula [4]:
LiNi _x Mn _2-x O ₄ (4)
In the above formula, 0.4? X? 0.6. The method of claim 1, wherein the gas discharge passage is located between the collector and the electrode mixture layer and / or between the separator and the electrode mixture layer . 7. The method of claim 6, wherein the gas discharge passage is located at least between the separator and the positive electrode mixture layer . delete delete [3] The method of claim 2, wherein the discharge passage scheduled portion is converted into a gas discharge passage only when the gas is discharged . The method according to claim 2, wherein the discharge passage scheduled portion is formed as a portion where the electrode mixture layer and the separation membrane are in close contact with each other with a relatively low coupling force . 12. The method of claim 11, going the exhaust passage portion formed between the electrode material mixture layer and the separator and the electrode the first bonding portion and the electrode is the first bond bonding between the mix layer and a separator that combines a portion of the anode mix layer and a separator than comprising a weak second joint, is a combination of the second joint in case of gas released from the electrode assembly manufacturing method of the electrode assembly characterized in that the conversion to the gas exhaust passage. The method of claim 1 or 2 , wherein the gas discharge passage or the discharge passage predetermined portion forms at least one strip structure in a plane . 14. The method of claim 13, wherein the width of the strip structure is 20% to 2000% based on the thickness of the electrode mixture layer . The method according to claim 1 or 2 , wherein the gas discharge passage or the discharge passage predetermined portion forms a net structure in a planar manner. The method of claim 1 or 2 , wherein the gas discharge passage or the discharge passage predetermined portion is formed in a lamination process . The secondary battery according to claim 1 or 2, wherein the electrode assembly is sealed inside the battery case together with the electrolyte solution. A battery pack comprising a secondary battery according to claim 17 as a unit battery. A device comprising the battery pack according to claim 18 as a power source. 20. The device of claim 19, wherein the device is a computer, a mobile phone, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle, a plug- , Or a system for power storage. delete delete delete delete delete The method of claim 2, wherein lamination is performed using a pressing member including two or more polygonal or circular protrusions on a surface of the electrode assembly facing the electrode assembly, Wherein the electrode assembly is made of a metal. The method as claimed in claim 2, wherein a cylindrical pressure roller having at least one protrusion on an outer surface facing the electrode assembly so that the gas discharge passage or the discharge passage predetermined portion of the strip structure or the net structure is formed in the step (c) Wherein the laminate is laminated by using the laminate .

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