KR100954591B1 - Electrode Assembly and Lithi? secondary Battery having the Same - Google Patents

Abstract

The present invention provides a lithium secondary battery comprising a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, an electrode assembly including a separator separating the positive electrode and the negative electrode and an electrolyte, wherein the separator comprises a ceramic material and It comprises a porous membrane made of a binder, the positive electrode active material layer comprises an olivine-based compound of the following [Formula 1], the particle size (particle size distribution D50 value) (A) of the olivine-based compound is 0.4 to 1.0 ㎛ The ceramic material has a particle size (particle size distribution D50 value) (B) of 0.04 to 1.0 μm, and the ratio (A / B) of the particle size of the olivine-based compound to the particle size of the ceramic material is 0.4 to 25. It relates to a secondary battery.

[Formula 1]

Li _y MXO _k (wherein M is Na, K, Mg, Ca, Sr, Ni, Co, Si, Ti, B, Al, Sn, Mn, Cr, Fe, Ce, V, Zr and combinations thereof At least one element selected from the group, X is at least one element selected from the group consisting of P, S, W, and a combination thereof, wherein 0 <y≤1, 2≤k≤4)

Therefore, the electrode assembly of the present invention and the lithium secondary battery including the same have excellent thermal stability by using an olivine-based compound as a positive electrode active material, and also have excellent particle size of the ceramic material and the olivine-based compound. By limiting the ratio of the silver particle size and the particle size of the olivine-based compound / particle size of the ceramic material, there is an effect that can provide a secondary battery excellent in battery stability.

Olivine, ceramic, binder

Description

Electrode Assembly and Lithium Secondary Battery Having Same {Electrode Assembly and Lithi㎛ secondary Battery having the Same}

The present invention relates to an electrode assembly and a lithium secondary battery having the same, and more particularly, to a lithium secondary battery having excellent thermal stability and battery stability in a secondary battery.

As miniaturization and light weight of portable electronic devices have recently advanced, the necessity for miniaturization and high capacity of batteries used as driving power sources thereof is increasing. In particular, the lithium secondary battery has an operating voltage of 3.6 V or more, which is three times higher than that of a nickel-cadmium battery or a nickel-hydrogen battery, which is widely used as a power source for portable electronic devices, and rapidly expands in terms of high energy density per unit weight. There is a trend.

Lithium secondary batteries generate electrical energy by oxidation and reduction reactions when lithium ions are intercalated / deintercalated at the positive and negative electrodes. The lithium secondary battery is prepared by using a material capable of reversibly intercalating / deintercalating lithium ions as an active material of a positive electrode and a negative electrode, and filling an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode.

A lithium secondary battery includes an electrode assembly in which a negative electrode plate and a positive electrode plate are wound in a form such as a jelly-roll with a separator interposed therebetween, a can containing the electrode assembly and an electrolyte, and a can It consists of a cap assembly assembled on the top.

As a cathode active material of a conventional lithium secondary battery, a lithium composite metal compound, for example, LiCoO ₂ , LiNiO _2, or LiMn ₂ O ₄ , is used. These materials have an advantage of having a high energy density and a high voltage.

However, these materials, particularly lithium cobalt oxide (LiCoO ₂ ), due to the side reaction between the surface of the lithium cobalt oxide active material and the organic electrolyte from a high temperature of more than 60 ℃ to generate a decomposition gas of the electrolyte inside the battery and the temperature of the battery for any reason When the temperature becomes more than 100 ° C., the structural change of the lithium cobalt oxide itself proceeds, thereby releasing oxygen (O ₂ ). At this time, the released oxygen plays a more active role in promoting the combustion reaction inside the battery, and when a small spark occurs, the internal pressure of the battery becomes so large that the can cannot withstand the battery. As a result, there is an increasing demand for new alternative materials that can be used as positive electrode active materials.

Accordingly, although it has been proposed to use an olivinic compound having excellent thermal stability as a cathode active material for a lithium secondary battery, even in the case of such an olivinic compound, battery stability due to battery internal short circuit or the like. There is a weak problem.

In particular, a conventional polyolefin-based microporous polymer membrane such as polypropylene, polyethylene, or a multilayer thereof is used. However, since the porous membrane layer has a sheet or film shape, an internal short circuit However, the sheet-like separator also shrinks due to pore blocking of the porous membrane due to heat generation due to overcharging or overcharging. Therefore, when an olivinic compound is used as the cathode active material, a method for satisfying thermal stability becomes more important. have.

Accordingly, the present invention is to solve the above-mentioned disadvantages and problems of the prior art, to provide an electrode assembly having a superior thermal stability and at the same time excellent battery stability in a lithium secondary battery and a lithium secondary battery having the same. There is a purpose.

The present invention includes an anode comprising a cathode active material layer; A negative electrode including a negative electrode active material layer; And a separator interposed between the positive electrode and the negative electrode, wherein the separator includes a porous film made of a ceramic material and a binder, and the positive electrode active material layer includes an olivine-based compound represented by the following [Formula 1], The particle size (particle size distribution D50 value) (A) of the compound is 0.4 to 1.0 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material is 0.04 to 1.0 μm, and the particle size / ceramic of the olivine compound The ratio (A / B) of the particle size of the material provides an electrode assembly, characterized in that 0.4 to 25.

[Formula 1]

Li _y MXO _k (wherein M is Na, K, Mg, Ca, Sr, Ni, Co, Si, Ti, B, Al, Sn, Mn, Cr, Fe, Ce, V, Zr and combinations thereof At least one element selected from the group, X is at least one element selected from the group consisting of P, S, W, and combinations thereof, wherein 0 <y≤1, 2≤k≤4)

The present invention also provides a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, an electrode assembly comprising a separator separating the positive electrode and the negative electrode and a lithium secondary battery comprising an electrolyte solution, wherein the separator is a ceramic It comprises a porous membrane made of a material and a binder, the positive electrode active material layer comprises an olivine-based compound of the following [Formula 1], the particle size (particle size distribution D50 value) (A) of the olivine-based compound is 0.4 to 1.0 ㎛ The ceramic material may have a particle size (particle size distribution D50 value) (B) of 0.04 to 1.0 μm, and a ratio (A / B) of the particle size of the olivine-based compound to the particle size of the ceramic material is 0.4 to 25. It provides a lithium secondary battery.

[Formula 1]

Li _y MXO _k (wherein M is Na, K, Mg, Ca, Sr, Ni, Co, Si, Ti, B, Al, Sn, Mn, Cr, Fe, Ce, V, Zr and combinations thereof At least one element selected from the group, X is at least one element selected from the group consisting of P, S, W, and a combination thereof, wherein 0 <y≤1, 2≤k≤4)

In addition, the present invention provides an electrode assembly and a lithium secondary battery having the positive electrode active material layer further comprises a compound capable of inserting and detaching at least one lithium ion.

In addition, the cathode active material layer is an electrode assembly, characterized in that the laminated structure of the first layer made of the olivine-based compound and the second layer made of a compound capable of inserting and detaching the lithium ion. Provided is a lithium secondary battery.

In addition, the cathode active material layer is an electrode assembly, characterized in that the laminated structure of the first layer made of a compound capable of inserting and detaching the lithium ion and the second layer made of the olivine-based compound Provided is a lithium secondary battery.

In addition, the present invention is the positive electrode active material layer is a laminated structure of the first layer made of the olivine-based compound, the second layer made of a compound capable of inserting and detaching the lithium ion and the third layer made of the olivine-based compound An electrode assembly and a lithium secondary battery having the same are provided.

Therefore, the electrode assembly of the present invention and the lithium secondary battery having the same include an olivine-based compound as a cathode active material, thereby providing a secondary battery having excellent thermal stability.

In addition, the present invention is the particle size of the ceramic material in the secondary battery using an olivine-based compound as a positive electrode active material, a porous film formed by the combination of a ceramic material and a binder as a separator, the olivine-based compound is a particle By limiting the ratio between the size and the particle size of the olivine-based compound / particle size of the ceramic material, there is an effect that can provide a secondary battery excellent in battery stability.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The details of the object and technical construction of the present invention and the resulting effects thereof will be more clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

In the drawings, the thicknesses, lengths, and the like of layers and regions may be exaggerated for convenience, and like reference numerals denote like elements throughout the specification.

First, Figure 1 shows an exploded perspective view of the electrode assembly according to an embodiment of the present invention.

Referring to FIG. 1, the electrode assembly 10 includes a first electrode plate 20 (hereinafter referred to as a positive electrode plate), a second electrode plate 30 (hereinafter referred to as a cathode plate), and a separator 40.

The electrode assembly 10 has the positive electrode plate 20, the negative electrode plate 30, and the separator 40 stacked and wound to form a jelly roll.

The separator 40 may include a first separator 40a positioned between the positive electrode plate 20 and the negative electrode plate 30 and a second separator 40b positioned below or above the two electrode plates 20 and 30. The two electrodes 20 and 30 to be stacked and wound are interposed in abutting portion to prevent a short circuit between the two electrode plates 20 and 30.

The positive electrode plate 20 is a positive electrode current collector 21 which collects electrons generated by a chemical reaction and transfers them to an external circuit, and a positive electrode active material in which a positive electrode slurry including a positive electrode active material is coated on one or both surfaces of the positive electrode current collector 21. Layer 22.

In addition, one side or both sides of both ends of the positive electrode current collector 21 is not coated with the slurry for the positive electrode including the positive electrode active material, so that the positive electrode non-coating portion 23 in which the positive electrode current collector 21 is exposed is formed.

The positive electrode non-coating portion 23 transfers electrons collected in the positive electrode current collector 21 to an external circuit, and a positive electrode tab 24, which may be formed of a thin plate made of nickel or aluminum, is bonded thereto.

The protection member 25 may be provided at an upper surface of the portion where the positive electrode tab 24 is bonded.

The protective member 25 is to protect a portion to be bonded to prevent a short circuit, and the like, and a material having heat resistance, for example, a polymer resin such as polyester may be preferable.

In addition, the positive electrode plate 20 may include an insulating member 26 formed to cover at least one of both ends of the positive electrode active material layer 22.

The insulating member 26 may be formed of an insulating tape, and may be formed of an adhesive layer and an insulating film attached to one surface of the adhesive layer, and the shape and material of the insulating member 26 are not limited in the present invention.

The negative electrode plate 30 is a negative electrode current collector 31, which collects electrons generated by a chemical reaction and transfers them to an external circuit, and a negative electrode on which one or both surfaces of the negative electrode current collector 31 are coated with a slurry for the negative electrode including a negative electrode active material. It consists of the active material layer 32.

In addition, one side or both sides of both terminals of the negative electrode current collector 31 is not coated with the negative electrode slurry containing the negative electrode active material, so that the negative electrode non-coating portion 33 in which the negative electrode current collector 31 is exposed is formed.

The negative electrode non-coating portion 33 transfers electrons collected in the negative electrode current collector 31 to an external circuit, and a negative electrode tab 34, which may be formed of a thin plate made of nickel, is bonded to the negative electrode non-coating portion 33.

A protective member 35 may be provided at an upper surface of a portion at which the negative electrode tab 34 is bonded.

The protective member 35 is to protect a portion to be joined to prevent a short circuit and the like, and a material having heat resistance, for example, a polymer resin such as polyester, may be preferable.

In addition, the negative electrode plate 30 may include an insulating member 36 formed to cover at least one of both ends of the negative electrode active material layer 32.

The insulating member 36 may be formed of an insulating tape, and may be formed of an adhesive layer and an insulating film attached to one surface of the adhesive layer, and the shape and material of the insulating member 36 are not limited in the present invention.

Subsequently, an electrode assembly including the separator of the present invention and a secondary battery having the same will be described below.

The separator 40 of the present invention comprises a porous film formed by bonding a ceramic material and a binder. The paste is prepared by mixing the ceramic material and the binder in a solvent, and then forming a porous film on the positive electrode or the negative electrode using the paste. In addition, as shown in Fig. 1, a porous membrane can be formed on both electrodes.

The ceramic material may be at least one material selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), and further, zirconium, Insulating nitrides, hydroxides, ketones, or mixtures of these compounds, each of aluminum, silicon, titanium, can be used. In this case, the limitation of insulating nitride is mentioned because titanium nitride (TiN) and the like have conductivity and are not suitable for the ceramic material of the present invention.

At this time, the ceramic material is characterized in that the particle size (particle size distribution D50 value) is 0.04㎛ to 1.0㎛.

In this case, the particle size distribution D50 value means a value of a size corresponding to 50% of the highest value in the cumulative distribution in the particle size analyzer measurement value, which is obvious in the art, and thus, the following description is omitted. Let's do it.

When the particle size (particle size distribution D50 value) of the ceramic material is less than 0.04 μm and more than 1.0 μm, there is a problem in that battery stability is not good, as will be compared in later examples and comparative examples.

The binder may be a synthetic rubber latex binder or an acrylic rubber having a crosslinked structure.

The synthetic rubber latex binder is styrene butadiene rubber (SBR) latex, nitrile butadiene rubber (NBR) latex, methyl methacrylate butadiene rubber latex, chloroprene rubber latex, carboxy modified styrene butadiene rubber latex and modified polyorganosiloxane polymer It may be one containing one or more selected from the group consisting of latex. It is preferable that such a polymer latex is made of an aqueous dispersion, and the content thereof is preferably used in an amount of 0.1 to 20 parts by weight as a solid with respect to 100 parts by weight of the electrode active material. There is a concern, and when it exceeds 20 parts by weight, since there is a possibility that adversely affect the battery characteristics, it is not preferable.

In addition, the acrylic rubber having the crosslinked structure may be formed by the crosslinking reaction of the polymer or copolymer of the acrylic main monomer with the crosslinkable comonomer. If only one type of polymer or copolymer of acrylic main monomer is used, the bonding structure is weak and easy to break. However, if a crosslinkable monomer is added to the polymer or copolymer of acrylic main monomer, the crosslinkable monomer is a polymer or copolymer structure of acrylic main monomer. It can be combined with to create a more rigid net structure. The polymer having such a net structure is less likely to swell in a solvent as the degree of crosslinking increases. The acrylic rubber binder having the crosslinking structure may have a three-dimensional crosslinking structure having 2 to 10 crosslinking points, preferably 4 to 5 crosslinking points, for 10,000 molecular weight units of the main chain molecule. Therefore, the acrylic rubber having a crosslinked structure of the present invention may have expansion resistance that does not swell when the electrolyte solution is moistened.

Due to the inherent characteristics of ceramic materials, acrylic rubber binders having a crosslinked structure having a decomposition temperature of 1000 ° C. or higher and a decomposition temperature of 250 ° C. or higher are used, so that a battery having high heat resistance can be obtained, thereby increasing stability against internal short circuits. .

The acrylic main monomers are methoxymethyl acrylate, methoxyethyl acrylate, (methoxyethyl acrylate), ethoxyethyl acrylate, butoxyethyl acrylate, methoxyethoxyethyl Alkoxyalkyl acrylate selected from methoxyethoxyethyl acrylate and dicyclopentenyloxyethyl acrylate; Vinyl methacrylate, vinyl acrylate, allyl methacrylate, 1,1-dimethylpropenyl methacrylate, 1,1-dimethyl Among propenyl acrylate (1,1-dimethylpropenyl acrylate), 3,3-dimethylbutenyl methacrylate (3,3-dimethylbutenyl methacrylate), 3,3-dimethylbutenyl acrylate (3,3-dimethylbutenyl acrylate) Alkenyl acrylate or alkenyl methacrylate selected; Unsaturated dicarboxylic acid esters selected from divinyl itaconate and divinyl maleate; Vinyl group-containing ethers selected from vinyl 1,1-dimethylpropenyl ether and vinyl 3,3-dimethylbutenyl ether; 1-acryloyloxy-1-phenylethene; And methyl methacrylate (methyl methacrylate) may be used one or more selected from the group consisting of.

The crosslinkable comonomers include 2-ethylhexyl acrylate, 2-methylhexyl acrylate, methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. ), An alkyl acrylate selected from octyl acrylate and isooctyl acrylate; an alkyl selected from vinyl chloroacetate and acryl chloroacetate. Alkenyl chloroacetate; Glycidyl group-containing esters or ethers selected from glycidyl acrylate, vinylglycidyl ether, and acryl glycidyl ether; Unsaturated carboxylic acids selected from acrylic acid, methacrylic acid and maleic acid; 2-chloroethyl vinyl ether; Chloromethyl styrene; And one or more selected from the group consisting of acrylonitrile can be used.

Next, an electrode assembly including the separator of the present invention and a secondary battery having the same include a positive electrode and a negative electrode.

The positive electrode 20 includes a positive electrode active material layer 22 and a positive electrode current collector 21 coated with the positive electrode active material.

Aluminum and an aluminum alloy may be used as the cathode current collector, and the cathode active material layer may include an olivine-based compound represented by the following [Formula 1].

[Formula 1]

Li _y MXO _k (wherein M is Na, K, Mg, Ca, Sr, Ni, Co, Si, Ti, B, Al, Sn, Mn, Cr, Fe, Ce, V, Zr and combinations thereof At least one element selected from the group, X is at least one element selected from the group consisting of P, S, W, and a combination thereof, wherein 0 <y≤1, 2≤k≤4)

The olivine-based compound has a thermal decomposition temperature of 270 ° C. or higher, and corresponds to a thermally stable material that does not chemically react with joule heat during initial short-circuit even when a short circuit occurs in the cell and does not pyrolyze even at a high temperature of 150 ° C. or higher. do.

At this time, the olivine-based compound is preferably LiFePo ₄ in the mass production potential, such as price, supply and demand, fairness.

At this time, the olivine-based compound is characterized in that the particle size (particle size distribution D50 value) is 0.4㎛ to 1.0㎛.

The particle size distribution D50 value refers to a value of a size corresponding to 50% of the highest value in the cumulative distribution in the particle size analyzer measurement value, which is obvious in the art, and thus the following description will be omitted. do.

When the particle size (particle size distribution D50 value) of the olivine-based compound is less than 0.4 μm and more than 1.0 μm, there is a problem in that battery stability is not good, as will be compared later in Examples and Comparative Examples.

In addition, in the present invention, the positive electrode active material may further include a material capable of inserting and detaching lithium ions, and as a representative example, the lithium-containing compound described below may be preferably used.

Li _x Mn _{1 - y} MyA ₂ (1)

Li _x Mn _{1 - y} M _y O _{2 - z} X _z (2)

Li _x Mn ₂ O _{4 - z} X _z (3)

Li _x Mn _{2 - y} M _y M ' _z A ₄ (4)

Li _x Co _{1 - y} M _y A ₂ (5)

Li _x Co _{1 - y} M _y O _{2 - z} X _z (6)

Li _x Ni _{1 - y} M _y A ₂ (7)

Li _x Ni _{1 - y} M _y O _{2 - z} X _z (8)

Li _x Ni _{1 - y} Co _y O _{2 - z} X _z (9)

Li _x Ni _{1 -y- z} Co _y M _z A _α (10)

Li _x Ni _{1 -y- z} Co _y M _z O _{2 -α} X _α (11)

Li _x Ni _{1 -y- z} Mn _y M _z A _α (12)

Li _x Ni _{1 -y- z} Mn _y M _z O _{2 -α} X _α (13)

(Wherein 0.9≤x≤1.1, 0≤y≤0.5, 0≤z≤0.5, 0≤α≤2, M and M 'are the same or different, Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V and rare earth elements, A is selected from the group consisting of O, F, S and P And X is selected from the group consisting of F, S and P.)

In this case, the positive electrode active material layer may be made of the olivine-based compound alone, and the compound capable of inserting and detaching the olivine-based compound and the lithium ions may be stacked. have. The olivine compound and the compound capable of inserting and desorbing the lithium ions are stacked to form a first layer comprising the olivine compound and a compound capable of inserting and detaching the lithium ions. It may be a laminated structure of two layers, and may also be a laminated structure of a first layer made of a compound capable of inserting and detaching the lithium ions and a second layer made of the olivine-based compound, and the olivine-based compound It may be a laminated structure of a first layer consisting of a second layer, a second layer made of a compound capable of inserting and detaching the lithium ions and a third layer made of the olivine-based compound.

In this case, in the particle size (A) of the olivine-based compound and the particle size (B) of the ceramic material, the ratio (A / B) of the particle size of the olivine-based compound / particle size of the ceramic material is 0.4 to 25 desirable.

In the case where the ratio (A / B) of the particle size of the olivine compound / ceramic material (A / B) is less than 0.4 and more than 25, as described in Examples and Comparative Examples, there is a problem that battery stability is not good. have.

The olivine-based compound does not undergo structural decomposition even at a higher temperature than conventional lithium composite metal compounds such as LiCoO ₂ , LiNiO _2, or LiMn ₂ O ₄ when the battery temperature rises due to an abnormal battery. Corresponding to a material having excellent thermal stability, and according to such excellent thermal stability, many studies have been made in recent years.

However, such an olivine-based compound has a problem in that the battery stability is weak because of the large amount of heat generated when an internal short circuit occurs. Therefore, in order to compensate for this problem in the present invention, by combining the ceramic material and the binder as described above. The porous membrane formed is used as a separator.

The separator including the porous membrane formed by the combination of the ceramic material and the binder is a heat-resistant layer that serves to prevent thermal diffusion when an internal short circuit occurs, thereby preventing the electrode from burning, but there is a problem that a conventional film-type separator shrinks at a high temperature. The porous membrane is not likely to shrink or melt.

In addition, the existing polyolefin-based film separator generates harder shorts because the peripheral film is continuously shrunk or melted in addition to the damaged part by the initial heat generation during internal short circuit, and the part where the film separator burns out becomes wider. However, the electrode on which the porous membrane is formed has only a small damage at the portion where the internal short circuit occurs, and does not lead to a phenomenon in which the short circuit portion is widened.

In particular, in the present invention, by using an olivine compound as the positive electrode active material, the thermal stability can be improved, and in the case of the olivine compound, the thermal stability is excellent, but the amount of heat generated when an internal short circuit occurs Due to its size, battery stability is not good. Therefore, by using a porous membrane formed by combining a ceramic material and a binder as a separator, battery stability can be compensated for by expanding the shot area.

In the present invention, the porous membrane may be formed in a form attached or coated on at least one surface of at least one electrode of the positive electrode and the negative electrode of the lithium secondary battery, wherein the porous membrane is a conventional polyethylene (PE), polypropylene (PP), etc. It may serve as a film-like separator made of a polyolefin resin film of the above, and the porous film may also serve as a separator together with film-like separators such as polyethylene (PE), polypropylene (PP) and the like.

In addition, the negative electrode 30 includes a negative electrode active material layer 32 and a negative electrode current collector 31 coated with the negative electrode active material.

Copper and a copper alloy may be used as the negative electrode current collector, and as the negative electrode active material, crystalline or amorphous carbon or a carbon-based negative electrode active material of a carbon composite may be used. It is not limited.

Next, the secondary battery provided with the electrode assembly containing the separator of this invention contains electrolyte solution.

The electrolyte according to the present invention includes a non-aqueous organic solvent, and the non-aqueous organic solvent may be carbonate, ester, ether or ketone. The carbonate may be dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC) ethylene carbonate (EC ), Propylene carbonate (PC), butylene carbonate (BC) and the like can be used, the ester is butyrolactone (BL), decanolide (decanolide), valerolactone (valerolactone), mevalonolactone ( mevalonolactone), caprolactone (caprolactone), n-methyl acetate, n-ethyl acetate, n-propyl acetate and the like can be used, the ether may be dibutyl ether and the like, the ketone polymethyl vinyl ketone However, the present invention is not limited to the type of non-aqueous organic solvent.

When the non-aqueous organic solvent is a carbonate-based organic solvent, it is preferable to use a mixture of cyclic carbonate and chain carbonate. In this case, the cyclic carbonate and the chain carbonate are preferably used by mixing in a volume ratio of 1: 1 to 1: 9, and more preferably used by mixing in a volume ratio of 1: 1.5 to 1: 4. The performance of the electrolyte is preferable when mixed in the above volume ratio.

The electrolyte solution of the present invention may further include an aromatic hydrocarbon organic solvent in the carbonate solvent. An aromatic hydrocarbon compound may be used as the aromatic hydrocarbon organic solvent.

Specific examples of the aromatic hydrocarbon-based organic solvent include benzene, fluorobenzene, chlorobenzene, nitrobenzene, toluene, fluorotoluene, trifluorotoluene, xylene and the like. In the electrolyte containing an aromatic hydrocarbon-based organic solvent, the volume ratio of the carbonate solvent / aromatic hydrocarbon solvent is preferably 1: 1 to 30: 1. The performance of the electrolyte is preferable when mixed in the above volume ratio.

In addition, the electrolyte according to the present invention includes a lithium salt, the lithium salt acts as a source of lithium ions in the battery to enable the operation of the basic lithium battery, for example LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x +1} SO ₂ ) (CyF _{2x + 1} SO ₂ ), where x and y are natural water and LiSO ₃ CF ₃ , including one or more or mixtures thereof.

At this time, the concentration of the lithium salt can be used within the range of 0.6 to 2.0M, preferably 0.7 to 1.6M range. If the concentration of the lithium salt is less than 0.6M, the conductivity of the electrolyte is lowered and the performance of the electrolyte is lowered. If the lithium salt is more than 2.0M, the viscosity of the electrolyte is increased, thereby reducing the mobility of lithium ions.

As described above, two electrodes are laminated or wound after lamination to form an electrode group in a porous film made of a ceramic material and a binder formed on the positive electrode or the negative electrode or both sides according to the present invention, and then placed in a can or a similar container. After the addition, the electrolyte is injected to prepare a lithium secondary battery.

In addition, the external shape of the lithium ion secondary battery produced by the above method is not limited, and, for example, a cylindrical, square or pouch type may be used.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited to the following examples.

Example 1

LiFePO ₄ as a positive electrode active material, polyvinylidene fluoride (PVDF) as a binder and carbon as a conductive agent were mixed in a weight ratio of 92: 4: 4, and then dispersed in N-methyl-2-pyrrolidone to prepare a positive electrode slurry. It was. The slurry was coated on an aluminum foil having a thickness of 20 μm, dried, and rolled to prepare a positive electrode. Artificial graphite as a negative electrode active material, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a thickener were mixed in a weight ratio of 96: 2: 2, and then dispersed in water to prepare a negative electrode active material slurry. The slurry was coated on copper foil, dried and rolled to prepare a negative electrode.

In addition, alumina (Al ₂ O ₃ ) is used as a ceramic material, acrylic rubber is mixed with a binder to form a porous film paste, and a porous film is formed between the cathode and the anode to form a separator, which is wound and compressed. Was inserted into a cylindrical can.

At this time, the particle size (particle size distribution D50 value) (A) of the olivine compound was 0.4 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.04 μm, and the particle size / The ratio (A / B) of the particle size of the ceramic material was set to 10.

An electrolyte was injected into the cylindrical can to prepare a lithium secondary battery.

[Example 2]

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.08 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that 6.2.

Example 3

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.6 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.1 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that the ratio was 6.

Example 4

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.7 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.2 μm, and the particle size / ceramic material of the olivine compound The particle size ratio of (A / B) was carried out in the same manner as in Example 1 except that 3.5 was set.

Example 5

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.8 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.3 μm, and the particle size / ceramic material of the olivine compound The particle size ratio of (A / B) was carried out in the same manner as in Example 1 except that 2.6.

Example 6

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.9 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.4 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that 2.2.

Example 7

The particle size (particle size distribution D50 value) (A) of the olivine compound was 1.0 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.5 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that the ratio was 2.

Example 8

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.4 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 1.0 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that the ratio was 0.4.

Example 9

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.7 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 1.0 μm, and the particle size / ceramic material of the olivine compound The particle size ratio of (A / B) was carried out in the same manner as in Example 1 except that 0.7 was set.

Example 10

The particle size (particle size distribution D50 value) (A) of the olivine compound was 1.0 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.1 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that 10 was set.

Example 11

The particle size (particle size distribution D50 value) (A) of the olivine compound was 1.0 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.05 μm, and the particle size / ceramic material of the olivine compound The particle size ratio of (A / B) was carried out in the same manner as in Example 1 except that the ratio was 20.

Example 12

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.04 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that 12.5.

Example 13

The particle size (particle size distribution D50 value) (A) of the olivine compound was 1.0 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.04 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that the ratio was 25.

Comparative Example 1

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.1 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.5 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that the ratio was 0.2.

Comparative Example 2

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.2 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.5 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that the ratio was 0.4.

Comparative Example 3

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.3 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.5 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that the ratio was 0.6.

[Comparative Example 4]

The particle size (particle size distribution D50 value) (A) of the olivine compound was 1.1 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.5 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that 2.2.

[Comparative Example 5]

The particle size (particle size distribution D50 value) (A) of the olivine compound was 1.2 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.5 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that the ratio was 2.4.

Comparative Example 6

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.01 μm, and the particle size / ceramic material of the olivine compound The particle size ratio of (A / B) was carried out in the same manner as in Example 1 except that 50 was set.

Comparative Example 7

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.02 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that the ratio was 25.

Comparative Example 8

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.03 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that the ratio was 16.

[Comparative Example 9]

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 1.1 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that 0.9 was set.

Comparative Example 10

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 1.2 μm, and the particle size / ceramic material of the olivine compound The ratio (A / B) of the particle size of was carried out in the same manner as in Example 1 except that the ratio was 0.4.

Comparative Example 11

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.5 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 2.5 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) of was carried out in the same manner as in Example 1 except that the ratio was 0.2.

Comparative Example 12

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.15 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.5 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) was carried out in the same manner as in Example 1 except that 0.3 was set.

Comparative Example 13

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.8 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.03 μm, and the particle size / ceramic material of the olivine compound The particle size ratio of (A / B) was carried out in the same manner as in Example 1 except that the ratio was 27.

Comparative Example 14

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.6 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.02 μm, and the particle size / ceramic material of the olivine compound The particle size ratio (A / B) was carried out in the same manner as in Example 1 except that the ratio was set to 30.

Comparative Example 15

The particle size (particle size distribution D50 value) (A) of the olivine compound was 0.7 μm, the particle size (particle size distribution D50 value) (B) of the ceramic material was 0.02 μm, and the particle size / ceramic material of the olivine compound The particle size ratio of (A / B) was carried out in the same manner as in Example 1 except that the ratio was 35.

Battery safety of the lithium batteries of Examples 1 to 13 and Comparative Examples 1 to 15 was measured. The battery safety was measured by nail penetration test and 150 ° C. thermal exposure characteristics.

First, nail penetrating experiments simulate consumer misuse, such as when a person intentionally pokes a battery with a nail, or when a nail is under pressure, such as a car wheel or a dog bites. If an external shock is applied to damage the appearance of the battery, the battery will be shorted to the outside. This is an experiment that simulates this case.

The mechanism of the nail penetration test shows that when a nail is punctured outside of the battery can, the nail passing through the can first penetrates the cathode surrounded by the outermost part of the jelly roll, and the portion where the nail that is equal to the cathode potential first contacts is the anode. When contacted with the aluminum current collector of the positive electrode, or the interface portion between the positive electrode current collector and the positive electrode active material layer, which is not the outermost surface layer of the active material layer, the energy is the greatest and the part becomes a heating element. Joule heat is generated in proportion to the square of the current at the time of short circuit, and the joule heat causes the anode to chemically react, react with the electrolyte to release gas, and oxygen due to the structural change of the cathode active material itself. It will explode with an occurrence. In addition, when the resistance of the portion where the internal short circuit occurs is low, the short circuit current easily flows, and the joule heat generated is further increased. For example, when the resistance of the current collector substrate itself is too low or the conductive agent is concentrated on the surface of the positive electrode active material layer, and the resistance decreases, the short circuit current is more likely to flow, which increases the risk of joule heat generation. will be. In addition, in the case of low speed nail penetration, the area shorted becomes larger and the time becomes longer, which is more dangerous.

Specifically, 100% full-charged battery was fully penetrated by a nail, and then confirmed whether or not an explosion occurred. When no abnormality was detected, "OK" was expressed, and when an explosion occurred, "NG" was expressed. Thirty of these were carried out, and the number of batteries was indicated before OK and NG.

Next, the 150 ° C thermal exposure characteristics are experiments that simulate the case where the consumer uses the battery in a high temperature place. For example, when a cell phone equipped with a battery is used in a steam room, a kitchen under heating, a car in midsummer, or by welding, the cell phone is usually placed in a high temperature environment of 90 ° C or higher. Normally, battery companies are testing thermal safety by thermal exposure to 150 ° C, which is much more severe than this temperature. The 150 ° C thermal exposure characteristics correspond to experiments that simulate this case.

Specifically, a 100% fully charged battery is placed in an oven and heated at a rate of 5 ° C./min, maintained for 1 hour after reaching 150 ° C. to check for ignition and explosion. In the case of ignition or explosion, it is indicated as "NG". Thirty of these were carried out, and the number of batteries was indicated before OK and NG.

The measurement results are shown in Table 1 below.

TABLE 1

division Olivine particle size (A) (㎛) Ceramic particle size (B) (㎛) A / B Nail Penetration Experiment 150 ℃ thermal exposure characteristics Example 1 0.4 0.04 10 30 OK 30 OK Example 2 0.5 0.08 6.2 30 OK 30 OK Example 3 0.6 0.1 6 30 OK 30 OK Example 4 0.7 0.2 3.5 30 OK 30 OK Example 5 0.8 0.3 2.6 30 OK 30 OK Example 6 0.9 0.4 2.2 30 OK 30 OK Example 7 1.0 0.5 2 30 OK 30 OK Example 8 0.4 1.0 0.4 30 OK 30 OK Example 9 0.7 1.0 0.7 30 OK 30 OK Example 10 1.0 0.1 10 30 OK 30 OK Example 11 1.0 0.05 20 30 OK 30 OK Example 12 0.5 0.04 12.5 30 OK 30 OK Example 13 10. 0.04 25 30 OK 30 OK Comparative Example 1 0.1 0.5 0.2 30 NG 20 NG, 10 OK Comparative Example 2 0.2 0.5 0.4 25 NG, 5 OK 17 NG, 13 OK Comparative Example 3 0.3 0.5 0.6 20 NG, 10 OK 15 NG, 15 OK Comparative Example 4 1.1 0.5 2.2 15 NG, 15 OK 25 NG, 5 OK Comparative Example 5 1.2 0.5 2.4 30 NG 20 NG, 10 OK Comparative Example 6 0.5 0.01 50 20 NG, 10 OK 30 NG Comparative Example 7 0.5 0.02 25 11 NG, 19 OK 22 NG, 8 OK Comparative Example 8 0.5 0.03 16 20 NG, 10 OK 25 NG, 5 OK Comparative Example 9 0.5 1.1 0.9 22 NG, 8 OK 23 NG, 7 OK Comparative Example 10 0.5 1.2 0.4 21 NG, 9 OK 21 NG, 9 OK Comparative Example 11 0.5 2.5 0.2 20 NG, 10 OK 22 NG, 8 OK Comparative Example 12 0.15 0.5 0.3 25 NG, 5 OK 25 NG, 5 OK Comparative Example 13 0.8 0.03 27 29 NG, 1 OK 20 NG, 10 OK Comparative Example 14 0.6 0.02 30 28 NG, 2 OK 24 NG, 6 OK Comparative Example 15 0.7 0.02 35 23 NG, 7 OK 20 NG, 10 OK

From the results shown in Table 1 above, Examples 1 to 13 show that the ceramic material has a particle size (particle size distribution D50 value) of 0.04 μm to 1.0 μm, and the olivine-based compound has a particle size (particle size distribution D50 value) of 0.4 μm. To 1.0 μm, the ratio (A / B) of the particle size (A) of the olivine-based compound to the particle size (B) of the ceramic material (A / B) of the olivine-based compound is 0.4-25. It can be seen that it is excellent in battery stability by satisfying both the nail penetration test and the 150 ° C. heat exposure characteristics.

However, in Comparative Examples 2, 3, 4, 5, 7, 8, 9, and 10, in which the ratio (A / B) of the particle size of the olivine-based compound / particle size of the ceramic material satisfies 0.4 to 25, the comparative example In the case of 2, 3, 4, and 5, the olivine-based compound has a particle size (particle size distribution D50 value) out of the range of 0.4 µm to 1.0 µm. It can be seen. In addition, in Comparative Examples 7, 8, 9, and 10, the ceramic material had a particle size (particle size distribution D50 value) out of the range of 0.04 µm to 1.0 µm. You can see this is not good.

Therefore, in the present invention, in order to improve battery stability, the ceramic material has a particle size (particle size distribution D50 value) of 0.04 μm to 1.0 μm, and the olivine-based compound has a particle size (particle size distribution D50 value) of 0.4 μm to 1.0 μm, In the particle size (A) of the olivine-based compound and the particle size (B) of the ceramic material, the ratio (A / B) of the particle size of the olivine-based compound / particle size of the ceramic material is preferably 0.4 to 25.

Although the present invention has been shown and described with reference to the preferred embodiments as described above, it is not limited to the above embodiments and those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

1 is an exploded perspective view of an electrode assembly according to an exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawing>

10: electrode assembly 20: bipolar plate

30 negative electrode plate 40 separator

21: positive electrode current collector 22: positive electrode active material layer

31: negative electrode current collector 32: negative electrode active material layer

Claims (13)

An anode including a cathode active material layer; A negative electrode including a negative electrode active material layer; And A separator interposed between the positive electrode and the negative electrode, The separator includes a porous film made of a ceramic material and a binder, The cathode active material layer includes an olivine-based compound of the following [Formula 1], The particle size (particle size distribution D50 value) (A) of the olivine-based compound is 0.4 to 1.0 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material is 0.04 to 1.0 μm, and the particles of the olivine-based compound Electrode assembly, characterized in that the ratio (A / B) of the size / particle size of the ceramic material is 0.4 to 25. [Formula 1] Li _y MXO _k (wherein M is Na, K, Mg, Ca, Sr, Ni, Co, Si, Ti, B, Al, Sn, Mn, Cr, Fe, Ce, V, Zr and combinations thereof At least one element selected from the group, X is at least one element selected from the group consisting of P, S, W, and a combination thereof, wherein 0 <y≤1, 2≤k≤4) The method of claim 1, The cathode active material layer further comprises a compound capable of inserting and detaching at least one lithium ion selected from the group consisting of the following formulas (1) to (13). Li _x Mn _{1 - y} MyA ₂ (1) Li _x Mn _{1 - y} M _y O _{2 - z} X _z (2) Li _x Mn ₂ O _{4 - z} X _z (3) Li _x Mn _{2 - y} M _y M ' _z A ₄ (4) Li _x Co _{1 - y} M _y A ₂ (5) Li _x Co _{1 - y} M _y O _{2 - z} X _z (6) Li _x Ni _{1 - y} M _y A ₂ (7) Li _x Ni _{1 - y} M _y O _{2 - z} X _z (8) Li _x Ni _{1 - y} Co _y O _{2 - z} X _z (9) Li _x Ni _{1 -y- z} Co _y M _z A _α (10) Li _x Ni _{1 -y- z} Co _y M _z O _{2 -α} X _α (11) Li _x Ni _{1 -y- z} Mn _y M _z A _α (12) Li _x Ni _{1 -y- z} Mn _y M _z O _{2 -α} X _α (13) (Wherein 0.9≤x≤1.1, 0≤y≤0.5, 0≤z≤0.5, 0≤α≤2, M and M 'are the same or different, Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V and rare earth elements, A is selected from the group consisting of O, F, S and P And X is selected from the group consisting of F, S and P.) The method of claim 2, The cathode active material layer is an electrode assembly, characterized in that the laminated structure of the first layer made of the olivine-based compound and the second layer made of a compound capable of inserting and detaching the lithium ions. The method of claim 2, The cathode active material layer is an electrode assembly, characterized in that the laminated structure of the first layer made of a compound capable of inserting and detaching the lithium ions and the second layer made of the olivine-based compound. The method of claim 2, The cathode active material layer is an electrode comprising a laminated structure of a first layer made of the olivine-based compound, a second layer made of a compound capable of inserting and detaching the lithium ions, and a third layer made of the olivine-based compound. Assembly. The method of claim 1, The olivine-based compound is an electrode assembly, characterized in that LiFePO ₄ . In a lithium secondary battery comprising a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, an electrode assembly comprising a separator separating the positive electrode and the negative electrode, and an electrolyte solution, The separator includes a porous film made of a ceramic material and a binder, The cathode active material layer includes an olivine-based compound of the following [Formula 1], The particle size (particle size distribution D50 value) (A) of the olivine-based compound is 0.4 to 1.0 μm, and the particle size (particle size distribution D50 value) (B) of the ceramic material is 0.04 to 1.0 μm, and the particles of the olivine-based compound A ratio (A / B) of the particle size of the size / ceramic material is 0.4 to 25. [Formula 1] Li _y MXO _k (wherein M is Na, K, Mg, Ca, Sr, Ni, Co, Si, Ti, B, Al, Sn, Mn, Cr, Fe, Ce, V, Zr and combinations thereof At least one element selected from the group, X is at least one element selected from the group consisting of P, S, W, and a combination thereof, wherein 0 <y≤1, 2≤k≤4) The method of claim 7, wherein The cathode active material layer further comprises a compound capable of inserting and detaching at least one lithium ion selected from the group consisting of the following formulas (1) to (13). Li _x Mn _{1 - y} MyA ₂ (1) Li _x Mn _{1 - y} M _y O _{2 - z} X _z (2) Li _x Mn ₂ O _{4 - z} X _z (3) Li _x Mn _{2 - y} M _y M ' _z A ₄ (4) Li _x Co _{1 - y} M _y A ₂ (5) Li _x Co _{1 - y} M _y O _{2 - z} X _z (6) Li _x Ni _{1 - y} M _y A ₂ (7) Li _x Ni _{1 - y} M _y O _{2 - z} X _z (8) Li _x Ni _{1 - y} Co _y O _{2 - z} X _z (9) Li _x Ni _{1 -y- z} Co _y M _z A _α (10) Li _x Ni _{1 -y- z} Co _y M _z O _{2 -α} X _α (11) Li _x Ni _{1 -y- z} Mn _y M _z A _α (12) Li _x Ni _{1 -y- z} Mn _y M _z O _{2 -α} X _α (13) (Wherein 0.9≤x≤1.1, 0≤y≤0.5, 0≤z≤0.5, 0≤α≤2, M and M 'are the same or different, Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V and rare earth elements, A is selected from the group consisting of O, F, S and P And X is selected from the group consisting of F, S and P.) The method of claim 8, The positive electrode active material layer is a lithium secondary battery, characterized in that the laminated structure of the first layer made of the olivine-based compound and the second layer made of a compound capable of inserting and detaching the lithium ions. The method of claim 8, The positive electrode active material layer is a lithium secondary battery, characterized in that the laminated structure of the first layer made of a compound capable of inserting and detaching the lithium ions and the second layer made of the olivine-based compound. The method of claim 8, The positive electrode active material layer is lithium, characterized in that the laminated structure of the first layer made of the olivine-based compound, the second layer made of a compound capable of inserting and detaching the lithium ions and the third layer made of the olivine-based compound. Secondary battery. The method of claim 7, wherein The olivine-based compound is LiFePO ₄ characterized in that the lithium secondary battery. The method of claim 7, wherein The electrolyte solution is a lithium secondary battery comprising a non-aqueous organic solvent and a lithium salt.

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