KR20130134910A - Electrode assembly and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to an electrode assembly and a lithium secondary battery comprising the same and, in particular, to an electrode assembly and a lithium secondary battery comprising the same wherein the electrode assembly comprises an cathode including a cathode active material, an anode including an anode active material containing a silicon-based material and a graphite-based material, and a separator membrane inserted between the cathode and the anode; and the separator membrane has inorganic particles and a polymer binder applied to either or both of the surfaces of a porous substrate. [Reference numerals] (AA) Capacity ratio(%);(BB) Cycle(time);(CC) Example 3;(DD) Comparative example 3

Description

Electrode assembly and Lithium secondary battery comprising the same {Electrode assembly and Lithium secondary battery comprising the same}

The present invention relates to an electrode assembly and a lithium secondary battery having improved lifetime and safety including the same.

Recently, interest in energy storage technology is increasing. As the field of application of cell phones, camcorders, laptops and PCs, and even electric vehicles is expanding, efforts for research and development of batteries are becoming more specific. Among them, secondary batteries are attracting attention because they can be charged and discharged. .

Secondary batteries are chemical cells capable of repeating charging and discharging using reversible interconversion of chemical energy and electrical energy, and are classified into Ni-MH secondary batteries and lithium secondary batteries. Examples of the lithium secondary battery include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery. Lithium secondary batteries are currently produced by many companies because of their high operating voltage and high energy density, compared to conventional Ni-MH batteries using aqueous electrolyte solutions, but their safety characteristics are different. The safety evaluation and safety of the battery are the most important matters to be considered. Accordingly, the safety standard of the lithium secondary battery strictly regulates ignition and smoke in the battery.

As a negative electrode active material of a lithium secondary battery, various types of carbon-based materials including artificial graphite, natural graphite, and hard carbon capable of inserting / desorbing lithium have been applied. The graphite of the carbon series has a low discharge voltage of -0.2V compared to lithium, and the battery using the negative electrode active material exhibits a high discharge voltage of 3.6V. Therefore, the graphite active material provides an advantage in terms of energy density of a lithium battery, and is widely used to ensure long life of a lithium secondary battery with excellent reversibility. However, the graphite active material has a low capacity in terms of energy density per unit volume of the electrode plate due to the low graphite density (theoretical density of 2.2 g / cc) when manufacturing the electrode plate, and at high discharge voltage, side reactions with the organic electrolyte used are likely to occur. There is a risk of fire or explosion due to battery malfunction or overcharging.

In addition, lithium ion batteries and lithium ion polymer batteries currently being produced use a polyolefin-based separator to prevent a short circuit between the positive electrode and the negative electrode. Since the polyolefin-based separator has physical properties that melt at 200 ° C. or lower, when the battery rises to a high temperature due to internal and / or external magnetic poles, a volume change such as shrinkage or melting of the separator occurs, and thus, between the two electrodes. An explosion may occur due to a short circuit, the release of electrical energy, or the like.

The present invention provides an electrode assembly and a lithium secondary battery having improved lifespan and safety including the same.

The present invention includes a positive electrode comprising a positive electrode active material; A negative electrode including a negative electrode active material including a silicon-based material and a graphite-based material; And a separator interposed between the anode and the cathode, wherein the separator provides an electrode assembly, wherein inorganic particles and a polymer binder are applied to at least one surface of the porous substrate.

The present invention improves life and safety by using a separator in which a negative electrode and an inorganic particle including a silicon-based material and a graphite-based material and a polymer binder are coated on a porous substrate.

1 and 2 are graphs showing charge and discharge cycles of a lithium secondary battery according to an embodiment of the present invention.

The present invention includes a positive electrode comprising a positive electrode active material; A negative electrode including a negative electrode active material including a silicon-based material and a graphite-based material; And a separator interposed between the anode and the cathode, wherein the separator provides an electrode assembly, wherein inorganic particles and a polymer binder are applied to at least one surface of the porous substrate.

Hereinafter, the electrode assembly of the present invention will be described in more detail.

An electrode assembly according to an embodiment of the present invention uses a silicon-based material having an electrochemical reversibility capable of occluding and releasing lithium together with a graphite-based material. When a silicon-based material having a lower electronic conductivity than a graphite-based material is mixed with a graphite-based material as a negative electrode active material, the silicon-based material decreases the electronic conductivity of the entire negative electrode, thereby increasing the resistance of the negative electrode by the reduced electron conductivity. In addition, the present invention not only significantly alleviates the instantaneous large amount of current conduction that occurs when the battery is short-circuited, but also reduces the thermal accumulation of the battery due to the large amount of current supply, thereby suppressing sudden ignition and explosion of the battery. In addition, unlike the conventional electrode additives, the silicon-based material has electrochemical reversibility, for example, an electrochemical property that occludes and releases lithium, and thus, battery performance caused by the use of an electrode additive that does not participate in a conventional battery reaction. Degradation problems such as deterioration of capacity, lifetime characteristics, etc. hardly occur, but the capacity increases in terms of energy density per unit volume. In addition, in the electrode assembly according to the exemplary embodiment of the present invention, the separator may include inorganic particles and a polymer binder such that volume change such as shrinkage or melting of the separator does not occur, thereby improving thermal safety and performance.

In the electrode assembly according to the embodiment of the present invention, the silicon-based material may be SiO _x (0 <x ≦ 1), specifically, silicon monoxide. Silicon particles generally used involve very complicated crystal changes in the reaction of electrochemically absorbing and storing lithium atoms. As the reaction of absorbing, storing and releasing lithium atoms proceeds, the composition and crystal structure of silicon particles are Si (crystal structure: Fd3m), LiSi (crystal structure: I41 / a), and Li ₂ Si (crystal structure: C2). / m), Li ₇ Si ₂ (Pbam), Li ₂₂ S _i5 (F23) and the like. In addition, the volume of the silicon particles expands about four times as the complex crystal structure changes. Therefore, when the charge and discharge cycle is repeated, the silicon particles are destroyed, and as the bond between the lithium atoms and the silicon particles is formed, the insertion sites of the lithium atoms initially possessed by the silicon particles are damaged and the cycle life is significantly reduced. In the case of SiO _x in the negative electrode active material according to the exemplary embodiment of the present invention, silicon atoms are covalently bonded to oxygen atoms. To combine with silicon atom is a lithium atom break the covalent bonds between the silicon atoms and oxygen atoms, but may be inserted because of a lack of energy to break the covalent lithium atom SiO _x structure is not destroyed. That is, the reaction between the SiO _x and the lithium atom can proceed while maintaining the SiO _x structure, so that the cycle life and capacity can be increased.

The silicon-based material may be coated with a carbon material, and the carbon material may be hard carbon or coke, needle coke, or coal tar pitch (coal), which is an amorphous carbon-based material obtained by thermally decomposing various organic materials such as phenol resin or furan resin. It may be a tar pitch, a soft carbon, such as an amorphous carbon material carbonized with a petroleum pitch, and may include a mixture of hard carbon and soft carbon.

In addition, in the electrode assembly according to the embodiment of the present invention, the silicon-based material and the graphite-based material are preferably in a weight ratio of 3 to 35:97 to 65. If the silicon-based material is less than 3 weight ratio, there is a problem that the capacity increase of the battery is not large, and if the silicon-based material exceeds 35 weight ratio, there is a problem that the cycle characteristics are lowered.

In the electrode assembly according to an embodiment of the present invention, the graphite-based material may include one or more selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), carbon fiber, carbon black. .

The inorganic particles are Pb (Zr, Ti) O ₃ , Pb _{1 - x} La _x Zr _{1 -y} Ti _y O ₃ (0 <x <1, 0 <y <1), PB (Mg ₃ Nb _2/3 ) From the group consisting of O ₃ -PbTiO ₃ , BaTiO ₃ , Hafnia (HfO ₂ ), SrTiO ₃ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , SnO ₂ , CeO ₂ , MgO, CaO, ZnO and Y ₂ O ₃ It may include one or more selected. The particle diameter of the inorganic particles is not limited, but is preferably 0.01 to 10 μm for forming a coating layer (coating layer) having a uniform thickness and appropriate porosity. If the particle diameter of the inorganic particles is less than 0.01 μm, the dispersibility of the inorganic particles is lowered, so that the particles may not be uniformly dispersed in the separator. If the particle size exceeds 10 μm, large pores may be formed in the coating layer to charge and discharge the battery. Internal short circuits may occur.

The polymer binder may be polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, Polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl co-vinyl acetate, polyethylene oxide, cellulose acetate ), Cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, Cyanoethyl sucrose (cyanoe) thylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide and butyl acrylate-ethyl acrylate It may include one or more selected from the group consisting of a cyano acrylic copolymer.

The porous substrate is a polyolefin-based porous substrate; Or a group consisting of polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfite, polyethylene naphthalene It may include one or more selected from.

The coating thickness of the inorganic particles and the polymer binder applied to the porous substrate is not limited to a specific range, but is preferably 0.01 to 20 μm.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + y} Mn _{2 - y} O ₄ (where y is 0-0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Ni-site type lithium nickel oxide represented by the formula LiNi _{1 - y} M _y O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and y = 0.01-0.3; Formula LiMn _{2 - y} M _y O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and y = 0.01-0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Ternary lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Ternary Lithium with Fe ₂ (MoO ₄ ) ₃ , Li (Ni _a Co _b Mn _c ) O ₂ (0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1) Transition metal composite oxides, and the like, but are not limited thereto.

The present invention also relates to a positive electrode comprising a positive electrode active material; A negative electrode including a negative electrode active material including a silicon-based material and a graphite-based material; And a separator interposed between the positive electrode and the negative electrode, wherein the separator provides a lithium secondary battery in which an electrode assembly and an electrolyte are housed in a case, wherein inorganic particles and a polymer binder are coated on at least one surface of a porous substrate. .

The lithium secondary battery according to an embodiment of the present invention may include all conventional lithium secondary batteries, such as a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

Lithium secondary battery according to an embodiment of the present invention can be prepared according to conventional methods known in the art. For example, it can be prepared by inserting a nonaqueous electrolyte through a separator between the positive electrode and the negative electrode. As described above, the separator is coated with at least one surface of the inorganic particles and the polymer binder on the porous substrate.

The electrolyte includes conventional electrolyte components such as electrolyte salts and organic solvents.

Using the electrolyte salts is A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+, and comprising an alkali metal cation or an ion composed of a combination thereof, such as K ^+, B ^- is PF ₆ ^{-, _{BF 4 -, Cl -, Br}} -, I -, ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 -, C (CF 2 SO 2) Salts containing ions consisting of anions such as ₃ ⁻ or combinations thereof. In particular, a lithium salt is preferable. For example, LiClO ₄ , LiCF ₃ SO ₃ , LiPF ₆ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) _2, or a mixture thereof may be used.

Organic solvents are commonly known solvents such as cyclic carbonates with or without halogen substituents; Linear carbonate system; Ester-based, nitrile-based, phosphate-based solvents, or mixtures thereof. For example, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, (NMP), ethylmethyl carbonate (EMC), gamma butyrolactone (GBL), fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, acetic acid Methyl, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate and butyl propionate or mixtures thereof.

The electrode of a lithium secondary battery can be manufactured by conventional methods known in the art. For example, a slurry may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant in an electrode active material, and then applying the coating (coating) to a current collector of a metal material, compressing, and drying the electrode to prepare an electrode. have.

The current collector of the metal material may be any metal that has high conductivity and can easily adhere to the slurry of the electrode active material and is not reactive in the voltage range of the battery. Non-limiting examples of the positive electrode current collector include aluminum, nickel, or a foil produced by a combination of these. Non-limiting examples of the negative electrode current collector include copper, gold, nickel, or a copper alloy or a combination thereof Foil and so on.

In order to bind the active material particles to the electrode of the lithium secondary battery, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), styrene-butadiene rubber (hereinafter referred to as SBR), etc. A binder is used. The binder is divided into a solvent-based binder represented by polyvinylidene fluoride (PVdF) (that is, a binder containing an organic solvent as a solvent) and an aqueous binder represented by styrene-butadiene rubber (that is, a binder containing water as a solvent). Unlike solvent binders, water based binders are economical, environmentally friendly, harmless to the health of workers, and have a greater binding effect than solvent based binders, thereby increasing the proportion of active materials of the same type, thereby enabling high capacity. The aqueous binder is preferably SBR and may be dispersed in water together with a thickening agent such as carboxymethylcellulose (CMC) to be applied to electrodes as well known.

The conductive material is not particularly limited as long as it is an electronic conductive material that does not cause chemical change in the electrochemical device. In general, acetylene black, carbon black, Denka black, graphite, carbon fiber, carbon nanotubes, metal powder, conductive metal oxide, organic conductive material and the like can be used.

Solvents for forming the electrode include organic solvents such as NMP (N-methyl pyrrolidone), DMF (dimethyl formamide), acetone, dimethyl acetamide or water, and these solvents are used alone or in combination of two or more. It can be mixed and used. However, water is used as a solvent when forming a cathode. The amount of the solvent used is sufficient to dissolve and disperse the electrode active material, the binder and the conductive agent in consideration of the coating thickness of the slurry and the production yield.

Lithium secondary battery according to an embodiment of the present invention is not limited in its appearance or case, it may be a cylindrical, square, pouch (coin) or coin type (coin) using a can.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example 1 Preparation of Electrode Assembly 1

1.1 Anode Manufacturing

92% by weight of lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, 4% by weight of polyvinylidene fluoride (PVdF) as a binder, and 4% by weight of carbon black as a conductive material were used as organic solvent N-methyl-2-pyrrolidone ( NMP) to prepare a positive electrode mixture slurry. The positive electrode mixture was applied to an aluminum thin film, which is a positive electrode current collector having a thickness of 20 μm, and dried, followed by a roll press process, to prepare a positive electrode.

1.2 Cathode Manufacturing

A negative electrode active material in which 5 wt% of carbon coated on the surface of SiO and graphite are mixed in a weight ratio of 3:97, denka black (DB) as a conductive material, SBR as a binder, and CMC as a thickener 97: 1: 1: 1 The mixture was mixed with water, and these were added to water as a solvent to prepare a slurry. The prepared slurry was applied to a thin copper film, dried, and then pressed to prepare a negative electrode.

1.3 Membrane Preparation

The polyvinylidene fluoride-hexafluoroethylene copolymer (PVdF-HFP) was added to acetone by about 5% by weight, and then dissolved at about 50 ° C. for about 12 hours to prepare a polymer solution. Alumina (Al ₂ O ₃ ) powder was added to the polymer solution at a concentration of 20% by weight of solids, followed by a ball mill process for 12 hours or more to prepare a slurry in which the alumina powder was crushed and dispersed. The alumina particle diameter in the prepared slurry can be controlled according to the size (particle size) of the beads used in the ball mill and the ball mill process time. In Example 1 of the present invention, the particle diameter of the pulverized alumina was about 400 nm. Subsequently, the slurry was applied at a thickness of 3 μm to the surface of the polyethylene separator of 9 μm using the dip coating method.

An electrode assembly was manufactured through the separator between the prepared anode and cathode.

Example 2 Preparation of Electrode Assembly 2

An electrode assembly was manufactured in the same manner as in Example 1, except that SiO, coated with 5 wt% carbon on the surface thereof, and graphite at a weight ratio of 35:65 were used as the negative electrode active material.

Example 3: Lithium Secondary Battery Manufacture 1

The separator was sandwiched between the positive electrode and the negative electrode prepared in Example 1, wound round, compressed to form a rectangular jelly-roll, and then inserted into a rectangular aluminum case to impregnate an electrolyte to prepare a rectangular battery. As the electrolyte, a nonaqueous electrolyte solution in which 1M LiPF ₆ was added to a nonaqueous electrolyte solvent in which ethylene carbonate (EC) and diethylene carbonate were mixed at a weight ratio of 3: 7 was used.

Example 4: Manufacture of Lithium Secondary Battery 2

A lithium secondary battery was manufactured in the same manner as in Example 3, except that the electrode assembly prepared in Example 2 was used and the form of the battery was cylindrical.

Comparative Example 1:

An electrode assembly was manufactured in the same manner as in Example 1, except that polyethylene separator (thickness 9 μm) was used as the separator.

Comparative Example 2:

An electrode assembly was manufactured in the same manner as in Example 2, except that a polyethylene separator (9 μm thick) was used as the separator.

Comparative Example 3:

Using the electrode assembly of Comparative Example 1, a lithium secondary battery was manufactured in the same manner as in Example 3.

Comparative Example 4:

Using the electrode assembly of Comparative Example 2, a lithium secondary battery was manufactured in the same manner as in Example 4.

Experimental Example 1: Charge-Discharge Cycle Experiment

Charge and discharge cycle experiments were performed at room temperature with the lithium secondary batteries prepared in Examples 3 to 4 and Comparative Examples 3 to 4 at 1C / 1C, and the results are shown in FIGS. 1 and 2.

As shown in FIG. 1, when comparing Example 3 according to an embodiment of the present invention with Comparative Example 3, a capacity ratio (capacity ratio when the first cycle capacity is set to 100) is almost similar to 100 charge / discharge cycles. However, it can be seen that the capacity reduction of Comparative Example 3 increases as the amount is exceeded 100 times, thereby increasing the gap between Example 3 and the capacity ratio. Therefore, it can be seen that Example 3 maintains a higher capacity ratio than Comparative Example 3 even when the number of charge and discharge cycles increases.

Referring to FIG. 2, it can be seen that in Comparative Example 4, when the charge / discharge cycle exceeds 150 times, the capacity ratio is sharply lowered, but in Example 4 according to an embodiment of the present invention, the capacity ratio gradually drops even after being exceeded 150 times. It can be seen that. As a result, even if the number of charge and discharge cycles increases, it can be seen that the capacity ratio of Example 4 is maintained longer than that of Comparative Example 4. Accordingly, it can be seen that the electrode assembly according to the embodiment of the present invention does not suddenly decrease in capacity even if the number of cycles increases, thereby improving the life of the secondary battery.

Experimental Example 2: Nail Penetration Experiment

The lithium secondary batteries prepared in Examples 3 to 4 and Comparative Examples 3 to 4 were fully charged under a voltage of 4.35 V and fired through the center of the lithium secondary battery using a nail with a diameter of 2.5 mm. Whether or not was observed. At this time, the nail penetration speed was variously performed at 1 m / min, 6 m / min, and 11 m / min.

Yes Nail Penetration Speed (m / min) Whether or not fired (number of fired batteries / number of batteries tested before) Example 3 One 0/10 6 0/10 Example 4 6 0/10 11 0/10 Comparative Example 3 One 10/10 6 0/10 Comparative Example 4 6 10/10 11 0/10

As shown in Table 1, in Example 3, no fired batteries were found when the nail penetration rates were 1 m / min and 6 m / min, and in Example 4, no fired batteries were found. . On the other hand, in Comparative Example 3, all of the batteries tested at 1 m / min nail penetration rate were fired, and in Comparative Example 4, all the cells tested at 6 m / min nail penetration rate were fired. Therefore, Examples 3 and 4 according to the present invention did not ignite regardless of the nail penetration rate, it can be seen that the safety of the lithium secondary battery is improved.

Claims (12)

A cathode comprising a cathode active material;
A negative electrode including a negative electrode active material including a silicon-based material and a graphite-based material; And
It includes a separator interposed between the positive electrode and the negative electrode,
The separator is an electrode assembly, characterized in that the inorganic particles and the polymer binder is applied to at least one surface of the porous substrate.
The method according to claim 1,
Wherein said silicon-based material is SiO _x (0 <x ≦ 1).
The method according to claim 1,
And the silicon-based material is coated with a carbon material.
The method according to claim 3,
The carbon material comprises soft carbon, hard carbon or a mixture thereof.
The method according to claim 1,
The silicon material and the graphite material is an electrode assembly, characterized in that the weight ratio of 3 to 35:97 to 65.
The method according to claim 1,
The graphite-based material is an electrode assembly, characterized in that it comprises at least one selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), carbon fiber, carbon black.
The method according to claim 1,
The inorganic particles are Pb (Zr, Ti) O ₃ , Pb _{1 - x} La _x Zr _{1 -y} Ti _y O ₃ (0 <x <1, 0 <y <1), PB (Mg ₃ Nb _2/3 ) From the group consisting of O ₃ -PbTiO ₃ , BaTiO ₃ , Hafnia (HfO ₂ ), SrTiO ₃ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , SnO ₂ , CeO ₂ , MgO, CaO, ZnO and Y ₂ O ₃ An electrode assembly comprising at least one selected.
The method according to claim 1,
The particle size of the inorganic particles is an electrode assembly, characterized in that 0.01 to 10 ㎛.
The method according to claim 1,
The polymer binder may be polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, Polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl co-vinyl acetate, polyethylene oxide, cellulose acetate ), Cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, Cyanoethyl sucrose (cyanoe) thylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide and butyl acrylate-ethyl acrylate -At least one member selected from the group consisting of cyano acrylic copolymers.
The method according to claim 1,
The porous substrate is a polyolefin-based porous substrate; Or a group consisting of polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfite, polyethylene naphthalene Electrode assembly comprising at least one selected from.
The method according to claim 1,
The positive electrode active material is lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), the formula Li _{1 + y} Mn _{2 - y} O ₄ (where y is 0-0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , lithium copper oxide (Li ₂ CuO ₂ ); LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ , the formula LiNi _{1 - y} M _y O ₂ , where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, y = 0.01-0.3), formula LiMn _{2 - y} M _y O ₂ , where M = Co, Ni, Fe, Cr, Zn or Ta, y = 0.01-0.1, Li ₂ Mn ₃ MO ₈ where M = Fe, Co, Ni, Cu or Zn, LiMn ₂ O ₄ , disulfide compound, Fe ₂ (MoO ₄ ) ₃ and Li (Ni _a Co _b Mn _c ) O ₂ (0 <a An electrode assembly comprising at least one member selected from the group consisting of ternary lithium transition metal composite oxides of <1, 0 <b <1, 0 <c <1, a + b + c = 1).
A lithium secondary battery in which the electrode assembly and the electrolyte of any one of claims 1 to 11 are housed in a case.

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