KR20170122000A - Novel precursor for cathode active material and preparing method thereof, and cathode active material using the same - Google Patents

Abstract

The present invention relates to an electroconductive precursor for a positive electrode active material including a composite transition metal hydroxide and a composite transition metal oxide, to a preparation method thereof and a positive electrode active material for a secondary battery manufactured from the precursor. Provided is a precursor for a positive electrode active material including a composite transition metal oxide and a composite transition metal hydroxide with large specific surface area and improved electric conductivity of powder, so output properties of a secondary battery having the positive electrode active material manufactured from the precursor can be improved.

Description

TECHNICAL FIELD The present invention relates to a novel cathode active material precursor and a cathode active material using the precursor, and to a cathode active material using the precursor,

The present invention relates to a novel cathode active material precursor having a high specific surface area and an excellent electric conductivity property, a method for producing the same, and a cathode active material for a secondary battery improved in electric conductivity and output characteristics including the precursor.

2. Description of the Related Art In recent years, a secondary battery with a high capacity has been required due to miniaturization of electronic devices. In particular, lithium secondary batteries having higher energy density than nickel-cadmium batteries and nickel-hydrogen batteries have attracted attention.

Lithium-containing cobalt oxide (LiCoO ₂ ) is mainly used as a positive electrode active material of a lithium secondary battery, and a lithium-containing manganese oxide such as LiMnO _{2 having a} layered crystal structure and LiMn ₂ O _{4 having a} spinel crystal structure, The use of LiNiO ₂ , which is a non-aqueous electrolyte, is also considered. Of the above cathode active materials, LiCoO ₂ is most widely used because of its excellent life characteristics and charge / discharge efficiency. However, LiCoO ₂ is expensive because of its small capacity and resource limitations of cobalt used as a raw material, so it is used as a power source for mid- Price competitiveness is limited. Lithium manganese oxides such as LiMnO ₂ and LiMn ₂ O ₄ are advantageous in that they are rich in manganese resources used as raw materials, are inexpensive, environmentally friendly, and excellent in thermal stability. However, they have small capacity, high temperature characteristics, This is a poor problem. In order to overcome such disadvantages, demand for a nickel rich system (Ni rich system) as a cathode active material of a secondary battery has begun to increase. The active material of the Ni-rich system has excellent advantages in terms of high capacity, but deterioration of the battery performance due to the reaction with the electrolyte is appearing.

On the other hand, the above-mentioned lithium complex transition metal oxide cathode active material is generally produced by a solid phase synthesis method using a complex transition metal precursor having a non-conductive property and a lithium precursor. The thus prepared cathode active material has a limitation in heightening the output characteristics of the battery itself because the electric conductivity is not high. In order to solve this problem, the conductive material having high electrical conductivity is used as a component of the anode, or the amount of the conductive material used is increased. In this case, however, the amount of the cathode active material is reduced by the amount of the conductive material. Therefore, there is an urgent need to develop a novel cathode active material capable of improving the electrochemical performance of a lithium secondary battery while improving the electrical conductivity of the cathode active material itself.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a novel cathode active material precursor having excellent electrical conductivity and high specific surface area, and a method for manufacturing the same, in place of the conventional insulating complex transition metal precursor The purpose.

It is another object of the present invention to provide a cathode active material for a secondary battery, which is produced from the above-mentioned electroconductive cathode active material precursor and a lithium precursor and can exhibit high output characteristics of the battery.

In order to achieve the above object, the present invention provides a composite transition metal hydroxide; And a complex transition metal oxide, and has an electric conductivity in the range of 0.01 to 0.1 mS / cm.

According to a preferred embodiment of the present invention, the cathode active material precursor may have a specific surface area of 50 to 200 m ² / g measured according to a nitrogen adsorption BET method.

Also, the cathode active material precursor has a plurality of micropores on its surface, and the pore volume of less than 10 nm may be in the range of 10 ^-3 to 5 10 ^-2 cm ³ / g · nm per particle weight.

In the present invention, the complex transition metal hydroxide and the complex transition metal oxide are preferably mixed or solid solution.

In the present invention, the cathode active material precursor is preferably represented by the following general formula (1).

[Chemical Formula 1]

(MOx) _A (M (OH) ₂ ) _B

In this formula,

M is Ni _a Co _b M ' _c ,

M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a Group 17 element, a transition metal,

1? X? 1.5, 0.6? A <1.0, 0? B? 0.4, 0? C? 0.4, a + b + c =

A + B = 1, 0.5? A < 1.0 and 0 < B? 0.5.

In the above formula (1), M 'is preferably at least one selected from the group consisting of Al, Mn, Zr, W, Ti, Mg, Sr, Ba, Ce, Hf, F, P, Also, A is preferably 0.6 or more and less than 1.0, and B is preferably more than 0 and not more than 0.4.

In addition, the present invention provides a cathode active material comprising the above-described cathode active material precursor and a lithium precursor.

In the present invention, the positive electrode active material preferably has a nickel (Ni) content of 60% or more and an electrical conductivity of 18 to 40 mS / cm in the total transition metal.

Further, the present invention provides a method for producing a precursor of a cathode active material represented by the above-mentioned formula (1).

More specifically, the method may include the step of heat-treating the complex transition metal hydroxide represented by Formula 2 at a temperature of 200 to 500 ° C. for 0.5 to 10 hours.

(2)

M (OH) ₂

In this formula,

M is Ni _a Co _b M ' _c ,

M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a Group 17 element, a transition metal and a rare earth element, 1.0, 0? B? 0.4, 0? C? 0.4, and a + b + c = 1.

In the present invention, the ratio of the complex transition metal oxide (A) to the complex transition metal hydroxide (B) according to Formula 1 is (i) the concentration of oxygen during heat treatment; (ii) the use of an oxidizing agent, or (iii) all of these.

In the present invention, by using a new cathode active material precursor having a high specific surface area and excellent electric conductivity instead of an insulating complex transition metal precursor used as a precursor of the cathode active material, the electric conductivity of the cathode active material prepared therefrom is improved, The characteristics can be improved.

FIG. 1 is a graph showing X-ray diffraction (XRD) results of the cathode active material precursor prepared in Example 1. FIG.
FIG. 2 is a graph showing the pore distribution of the cathode active material precursor prepared in Example 1 and Comparative Example 1. FIG.

Hereinafter, the present invention will be described in detail.

In the present invention, a novel composite transition metal precursor having improved electrical conductivity and large specific surface area is used as a precursor of a cathode active material instead of the conventional insulating complex transition metal precursor.

More specifically, in the present invention, the hydroxide complex transition metal precursor produced through the conventional co-precipitation process is subjected to a heat treatment process. In the composite transition metal precursor produced through such processes, a part of the complex transition metal hydroxide as a reactant is oxidized to produce a complex transition metal oxide, and the hydroxide-based and oxide-based complex transition metal precursors They have a structure in which they are mixed.

The cathode active material precursor of the present invention in which the hydroxide-based and oxide-based complex transition metal precursors are mixed in this way exhibits excellent electrical conductivity unlike the conventional insulating precursor. Accordingly, the positive electrode active material produced through the solid-phase reaction between the complex transition metal precursor and the lithium precursor exhibits excellent electrical conductivity by itself, so that the output characteristics of the secondary battery including the positive electrode active material can be significantly improved. Particularly, in the present invention, even when a conductive material is not used or a smaller amount of the conductive material than that of a conventional conductive material is used in producing the anode, it can exhibit electrical conductivity equivalent to that of a conventional anode. At the same time, since the amount of the positive electrode active material used can be increased by the reduced amount of the conductive material, high capacity characteristics of the battery can be exhibited.

In addition, the cathode active material precursor has an increase in specific surface area about 10 times or more as compared with the conventional composite transition metal precursor. By applying the precursor having a relatively large specific surface area as described above, the solid-phase reaction with the lithium precursor is activated, thereby reducing the reaction time between the precursors and producing a cathode active material exhibiting high output. In particular, the high-Ni-based cathode active material having a high nickel content may reduce the cation mixing occurring during the long-time firing at a high temperature.

&Lt; Precursor for a new cathode active material and method for producing the same &

The cathode active material precursor according to the present invention includes both a hydroxide-based complex transition metal precursor and an oxide-based complex transition metal precursor, and is characterized by exhibiting electrical conductivity, not insulation.

More specifically, the cathode active material precursor includes (a) a complex transition metal hydroxide [M (OH) ₂ ] and (b) a complex transition metal oxide [MOx].

The complex transition metal hydroxide (a) and the complex transition metal component (M) contained in the complex transition metal oxide (b) may be the same or different from each other. Here, since the precursor of the cathode active material is produced through a heat treatment process of a hydroxide-based complex transition metal precursor, the complex transition metal hydroxide and the complex transition metal component (M) contained in the complex transition metal oxide are preferably the same .

In addition, the complex transition metal hydroxide and the complex transition metal oxide may be in a mixed state or in a solid solution form. In the present invention, a solid solution refers to a mixture of solids forming a completely uniform phase, and includes both interstitial solid solution and substituted solid solution.

The cathode active material precursor according to the present invention shows a first peak derived from a hydroxide system and a second peak derived from an oxide system in an X-ray diffraction spectrum (XRD), which indicates that a hydroxide system and an oxide system are simultaneously included.

More specifically, the cathode active material precursor of the present invention has a first peak derived from a hydroxide, which diffraction angle (2?) Of the X-ray diffraction spectrum appears at 18 to 20 °, 33 to 35 °, and 38 to 40 °; And a second peak derived from an oxide appearing at diffraction angles (2?) Of 36 to 38 °, 42 to 44 °, 62 to 64 °, and 75 to 80 °. The intensity of the two phases may vary depending on the ratio of the complex transition metal hydroxide (a) and the complex transition metal oxide (b).

In the present invention, the content ratio of the complex transition metal hydroxide (a) and the complex transition metal oxide (b) is not particularly limited, and for example, the complex transition metal hydroxide (a) : 0.1 to 50 weight ratio, preferably 60 to 99.0: 1.0 to 40.

The cathode active material precursor of the present invention comprising the above-mentioned hydroxide-based (a) and oxide-based (b) complex transition metal precursor itself exhibits excellent electrical conductivity. The electrical conductivity of the cathode active material precursor may range from 0.01 to 0.1 mS / cm, and preferably from 0.03 to 0.07 mS / cm.

In addition, since the positive electrode active material precursor has many micropores on its surface, the specific surface area of the positive electrode active material precursor is increased unlike the conventional complex transition metal precursor. That is, the cathode active material precursor of the present invention is synthesized through a heat treatment process at a low temperature. During the low-temperature heat treatment process, moisture is evaporated from the hydroxide precursor, thereby increasing pores on the surface, thereby increasing the specific surface area of the cathode active material precursor. Unlike the conventional precursor in which the pore is hardly present on the surface of the cathode active material precursor, micropores exist on the surface of the precursor. Accordingly, the cathode active material precursor of the present invention may have a specific surface area of 50 to 200 m ² / g, preferably 100 to 170 m ² / g, measured according to the nitrogen adsorption BET method.

The cathode active material precursor according to the present invention is preferably represented by the following general formula (1).

[Chemical Formula 1]

(MOx) _A (M (OH) ₂ ) _B

In this formula,

M is Ni _a Co _b M ' _c ,

M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a Group 17 element, a transition metal,

1? X? 1.5, 0.6? A <1.0, 0? B? 0.4, 0? C? 0.4, a + b + c =

A + B = 1, 0.5? A < 1.0 and 0 < B? 0.5.

In the above formula (1), a, b, and c represent mol% of each element in the compound, and x represents an oxygen fraction in the compound. Also, A and B represent the content ratio between the hydroxide system and the oxide precursor.

In particular, in the cathode active material of the present invention, the content of nickel (Ni) as a may be 0.6 or more, preferably 0.6 to 0.9, and more preferably 0.7 to 0.9. The oxygen fraction of x may be 1 or more, preferably 1 to 1.5. It is preferable that A is 0.6 or more and less than 1.0, and B is more than 0 and 0.4 or less.

When the above ranges of a, x, A and B are satisfied, it is possible to easily produce a positive electrode active material having excellent electrical conductivity and high specific surface area, particularly a high-Ni positive electrode active material, (High output characteristics, high initial capacity, and long life characteristics).

In the present invention, by substituting M 'such as a small amount of a different kind of metal, quasi metal or other anion component into the high-Ni composite oxide, even if the Ni content is increased to 60% or more, the structural stability of the final cathode active material The electrochemical characteristics can be continuously maintained.

According to a preferred embodiment of the present invention, M 'is at least one element selected from the group consisting of Al, Mn, Zr, W, Ti, Mg, Sr, Ba, Ce, Hf, F, P, .

In the present invention, the cathode active material precursor may be a primary particle or a secondary particle in which a plurality of primary particles are aggregated. In this case, the primary particles may have a flake shape or a Niddle shape with an average particle diameter ranging from 0.01 to 0.8 mu m. The secondary particles in which the primary particles are aggregated may have a spherical shape having an average particle diameter (D50) in the range of 3 to 30 占 퐉, but are not particularly limited thereto. In X-ray diffraction analysis, the lattice constant of the precursor has a value of a = b = c.

In addition, the cathode active material precursor may have a plurality of micropores and mesopores on the surface and / or inside thereof, and most of the pores may have pores of less than 10 nm. And the cathode active material precursor may have a pore volume less than 10 nm in the range of 10 ^-3 to 5 × 10 ^-2 cm ³ / g · nm per particle weight.

In the present invention, pores are defined as micropores having a pore diameter of less than 2 nm, mesopores having a diameter of 2 to 50 nm, and pores having a diameter of more than 50 nm according to the definition of International Union of Pure and Applied Chemistry (IUPAC) And macropores, respectively.

The complex transition metal oxide precursor powder preferably has a tap density of 2.0 g / cc or more, more preferably 2.1 g / cc or more.

Hereinafter, a method for producing the positive electrode active material precursor according to the present invention will be described. However, the present invention is not limited to the following production methods, and the steps of each process may be modified or selectively mixed if necessary.

For example, the composite transition metal hydroxide may be heat-treated at a temperature of 200 to 500 ° C for 0.5 to 10 hours to produce the cathode active material precursor.

At this time, the complex transition metal hydroxide precursor is not particularly limited as long as it contains nickel in a high content and is in the form of hydroxide. Can be represented by the following formula (2).

(2)

M (OH) ₂

In this formula,

M is Ni _a Co _b M ' _c ,

M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a Group 17 element, a transition metal and a rare earth element, 1.0, 0? B? 0.4, 0? C? 0.4, and a + b + c = 1.

According to a preferred embodiment of the present invention, M 'is at least one element selected from the group consisting of Al, Mn, Zr, W, Ti, Mg, Sr, Ba, Ce, Hf, F, P, .

The heat treatment conditions are not particularly limited. For example, the heat treatment may be performed at 200 to 500 ° C for 0.5 to 10 hours, preferably at 250 to 450 ° C.

As described above, when the composite metal hydroxide precursor is heat-treated in an oxygen atmosphere, a part of the hydroxide precursor is oxidized to form an oxide precursor, and the structure in which the hydroxide precursor and the oxide precursor are mixed is present .

In the present invention, the ratio of the complex transition metal oxide (A) and the complex transition metal hydroxide (B) constituting the precursor of the cathode active material of Formula 1 can be easily controlled.

At this time, the ratio of the complex transition metal oxide (A) to the complex transition metal hydroxide (B) can be largely divided into three methods, for example, (i) (ii) the use of an oxidizing agent, or (iii) all of these.

The oxidizing agent may be selected from the group consisting of KMnO ₄ , H ₂ O _2, Na ₂ O ₂ , FeCl ₃ , CuSO ₄ , CuO, PbO ₂ , MnO ₂ , HNO ₃ , At least one selected from KNO ₃ , K ₂ Cr ₂ O ₇ , CrO ₃ , P ₂ O _5, H ₂ SO ₄ , K ₂ S ₂ O ₈ , halogens and C ₆ H ₅ NO ₂ can be used.

<Cathode Active Material>

The cathode active material according to the present invention is a lithium complex transition metal oxide prepared from the above-mentioned oxide conductive agent and hydroxide-based conductive cathode active material precursor.

More specifically, the cathode active material may be represented by the following general formula (3).

(3)

Li _y Ni _a Co _b M ' _c O ₂

In Formula 3,

M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a group 15 element, a group 16 element, a group 17 element, a transition metal,

0.6? A <1.0, 0? B? 0.4, 0? C? 0.4, a + b + c = 1, and 0.9? Y? 1.3.

According to a preferred embodiment of the present invention, M 'is at least one element selected from the group consisting of Al, Mn, Zr, W, Ti, Mg, Sr, Ba, Ce, Hf, F, P, .

In the present invention, the cathode active material may be an Ni-rich system active material having a nickel (Ni) content of 60% or more, preferably 60 to 90%, more preferably 70 To 90%.

Also, the cathode active material exhibits superior electrical conductivity than the cathode active material prepared from the conventional insulating complex transition metal precursor. For example, the electrical conductivity may be 18 to 40 mS / cm, preferably 18 to 28 mS / cm, and more preferably 20 to 25 mS / cm.

The average particle diameter of the cathode active material is not particularly limited as long as it is a typical range that can be used as an active material. For example, in the range of 5 to 30 mu m, preferably in the range of 5 to 20 mu m.

The cathode active material of the present invention can be produced according to a conventional method known in the art, and can be produced, for example, by a dry method, a wet method, or a combination thereof.

An example of the method for producing the cathode active material may be a solid phase reaction in which the precursor of an electroconductive cathode active material containing an oxide system and a hydroxide system is mixed with a lithium precursor and then heat-treated.

Here, the lithium precursor is not particularly limited as long as it can be used as a source including lithium. Preferably it may be LiOH, Li ₂ CO ₃ or a mixture thereof.

Also, the mixing ratio of the electrically conductive cathode active material precursor and the lithium precursor may be appropriately adjusted within the conventional range known in the art, and may be, for example, in the range of 1: 0.95 to 1.15 weight ratio.

By mixing the cathode active material precursor and the lithium precursor and performing the heat treatment as described above, lithium in the crystal structure is substituted to form a lithium complex transition metal oxide.

The heat treatment conditions are not particularly limited. For example, the heat treatment is preferably performed for 1 to 24 hours under an atmospheric condition of 700 to 1000 ° C.

If necessary, it may further be subjected to a secondary heat treatment step or further include a classification step.

The cathode active material prepared in the present invention is mainly used as a cathode material for a secondary battery, and may be used in various fields in which the above-described structure can be applied.

<Anode>

The present invention provides a cathode material for a secondary battery and a lithium secondary battery including the same.

At this time, the cathode material of the present invention is required to include a cathode active material prepared from an electrically conductive cathode active material precursor containing at least the oxide system and the hydroxide system. For example, the positive electrode active material itself may be used as a positive electrode active material, or a positive electrode material mixture in which the positive electrode active material and a binder are mixed, a positive electrode material mixture paste obtained by further adding a solvent, It falls within the scope of the anode material of the invention.

The anode may be manufactured by a conventional method known in the art. For example, a slurry is prepared by mixing and stirring a binder, a conductive agent, and a dispersant, if necessary, in a cathode active material, Followed by compression and drying.

The electrode material such as dispersion medium, binder, conductive agent, current collector and the like may be any of those conventionally known in the art. The binder may be suitably used in an amount of 1 to 10 parts by weight based on the weight of the positive electrode active material and 1 to 30 parts by weight of the conductive material. .

Examples of usable conductive agents include natural graphite, artificial graphite, carbon black, acetylene black or Gulf Oil Company, ketjen black, Vulcan XC-72, Super P, coke, carbon nanotubes, And mixtures of one or more of these.

Typical examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF) or a copolymer thereof, styrene butadiene rubber (SBR), cellulose and the like. Representative examples of the dispersing agent include isopropyl alcohol, N Methylpyrrolidone (NMP), acetone, and the like.

The current collector of the metal material may be any metal that has high conductivity and is a metal that can easily adhere the paste of the material and does not have reactivity in the voltage range of the battery. For example, a mesh, a foil, or the like of aluminum, copper, or stainless steel may be used.

<Lithium secondary battery>

In addition, the present invention provides a secondary battery comprising the anode, preferably a lithium secondary battery.

The lithium secondary battery of the present invention is not particularly limited except that a cathode active material prepared from the above-described oxide-based and hydroxide-based electrically conductive cathode active material precursor is used, and can be produced by a conventional method known in the art have. For example, a separation membrane may be inserted between an anode and a cathode, and a nonaqueous electrolyte may be charged.

The lithium secondary battery of the present invention includes a cathode, a cathode, a separator, and an electrolyte as battery components. Components of the anode, the separator, the electrolyte, and other additives, if necessary, other than the cathode described above, Which is the same as that of the lithium secondary battery.

For example, the negative electrode may be a negative electrode active material for a lithium secondary battery known in the art. As a non-limiting example, a material capable of intercalating / deintercalating lithium is used. For example, Lithium alloys, coke, artificial graphite, natural graphite, combustibles of organic polymer compounds, carbon fibers, silicones, and tin-based alloys. The conductive agent, binder and solvent are used in the same manner as in the case of the positive electrode described above.

Also, the non-aqueous electrolyte includes electrolytic components commonly known in the art, such as an electrolyte salt and an electrolyte solvent.

(I) a cation selected from the group consisting of Li ⁺ , Na ⁺ , K ⁺ and (ii) a cation selected from the group consisting of PF ₆ ^- , BF ₄ ^- , Cl ^- , Br ^- , I ^- , ClO ₄ ^- , AsF ₆ ^- A combination of anions selected from the group consisting of CH ₃ CO ₂ ^- , CF ₃ SO ₃ ^- , N (CF ₃ SO ₂ ) ₂ ^- and C (CF ₂ SO ₂ ) ₃ ^- . Specific examples of the lithium salt include LiClO ₄ , LiCF ₃ SO ₃ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , and LiN (CF ₃ SO ₂ ) ₂ . These electrolyte salts may be used alone or in combination of two or more.

The electrolyte solvent may be selected from cyclic carbonates, linear carbonates, lactones, ethers, esters, acetonitriles, lactams, and ketones.

Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and fluoroethylene carbonate (FEC). Examples of the linear carbonate include diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), and methyl propyl carbonate (MPC). Examples of the lactone include gamma butyrolactone (GBL), and examples of the ether include dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and the like. Examples of the ester include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl pivalate and the like. Examples of the lactam include N-methyl-2-pyrrolidone (NMP), and the ketone is polymethyl vinyl ketone. The halogen derivative of the organic solvent may be used, but is not limited thereto. In addition, the organic solvent may be glyme, diglyme, triglyme, or tetraglyme. These organic solvents may be used alone or in combination of two or more.

The separator may use any porous material that interrupts the internal short circuit of both electrodes and impregnates the electrolyte. Examples thereof include polypropylene-based, polyethylene-based, polyolefin-based porous separation membranes, or composite porous separation membranes in which an inorganic material is added to the above-mentioned porous separation membranes.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the scope of the present invention is not limited by the following Examples and Experimental Examples.

[Example 1]

1-1. Manufacture of cathode active material precursor

_{Ni 0.8 Co 0.1 Mn 0.1 (OH} ) 2 by a heat treatment at 300 ℃ for 3 hours embodiment the positive electrode active material precursor of Example _{1 (Ni 0.8 Co 0.1 Mn 0.1} O 1.05) 0.89 · (Ni 0.8 Co 0.1 Mn 0.1 (OH) 2) _0.11 .

1-2. Cathode active material manufacturing

(Ni _0.8 Co _0.1 Mn _0.1 O _1.05 ) _0.89 (Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ ) _0.11 ) prepared in Example 1-1 and LiOH · H ₂ O as a lithium compound were used as the cathode active material precursor And the mixture was heat-treated at 800 ° C. for 12 hours to prepare a cathode active material of Example 1.

1-3. Anode manufacturing

95 parts by weight of the cathode active material prepared in Example 1-2, 2.5 parts by weight of the PvdF binder, and 2.5 parts by weight of carbon black as a conductive material were dispersed in an NMP solution to prepare a slurry, which was then applied to the Al current collector. And then rolled by a roll press to produce a positive electrode

1-4. Lithium secondary battery manufacturing

A coin cell was prepared using the electrolyte prepared from EC / EMC / DEC (40/30/30, volume ratio) and 1M LiPF ₄ using the positive electrode and lithium metal prepared in Example 1-3 as a counter electrode, .

[Comparative Example 1]

The hydroxide precursor and lithium precursor were mixed at a molar ratio of 1: 1.01 using Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ and LiOH, respectively, and then heat-treated at 800 ° C for 12 hours to prepare a cathode active material of Comparative Example 1.

A positive electrode of Comparative Example 1 and a lithium secondary battery having the positive electrode were fabricated in the same manner as in Example 1 except that the positive electrode active material was used.

[Experimental Example 1] X-ray diffraction analysis (XRD) of the cathode active material precursor

XRD analysis was performed using the cathode active material precursor prepared in Example 1.

The XRD analyzer used PANalytical X'Rert PRO model and the X-ray source used Cu κα 8048eV. At this time, the diffraction angle 2? Was measured in the range of 10 to 90 degrees, and the scanning speed was 0.9sec / step, and the results are shown in FIG.

As a result of the experiment, the cathode active material precursor of Example 1 had both a specific peak derived from hydroxide and a specific peak derived from oxide. As a result, it was confirmed that the precursor of the cathode active material of the present invention had a complex transition metal hydroxide and a complex transition metal oxide form simultaneously (see FIG. 1).

[Experimental Example 2] Evaluation of specific surface area and porosity distribution (BET) of the cathode active material precursor

The specific surface area and porosity distribution were measured using the cathode active material precursor prepared in Example 1 and Comparative Example 1, respectively.

The specific surface area and the porosity distribution (Porous Distribution) were pre-treated at 130 ° C for 3 hours using 3 g of the cathode active material precursor, and then measured under a nitrogen atmosphere at a pressure of 0.01 to 0.2. The measured specific surface area and pore distribution are shown in Table 1 and FIG.

Specific surface area (m ² / g) Comparative Example 1 12 Example 1 148

As a result of the experiment, the pore distribution of the precursor of the cathode active material prepared in Example 1 and Comparative Example 1 showed that the precursor of the hydroxide type Comparative Example 1 had substantially no pores on the surface and had a significantly low specific surface area.

In contrast, the positive electrode active material precursor of Example 1 has a specific surface area increased by 10 times or more as compared with Comparative Example 1, and a relatively large number of micropores exist (see FIG. 2). This increase in specific surface area and surface micropores improves the reactivity in the solid phase reaction between lithium and the precursor, which is a factor that can improve the output characteristics of the cathode active material.

[Experimental Example 3] Evaluation of electrical conductivity of a cathode active material precursor

The electrical conductivity was measured using the cathode active material precursor prepared in Example 1 and Comparative Example 1, respectively.

The electrical conductivity was measured by using 3 g of the cathode active material precursor under a pressure of 20 kN. The results are shown in Table 2 below.

Precursor electrical conductivity
(mS / cm) Electrical Conductivity of Cathode Active Material
(mS / cm) Comparative Example 1 0.00000 16.43 Example 1 0.04581 23.59

As a result of the test, the precursor of Comparative Example 1 in the hydroxide form in the past exhibited the property of the nonconductor. In contrast, the positive electrode active material precursor of Example 1 exhibited a significant increase in electric conductivity and had excellent electrical conductivity (see Table 2). It was found that the increase of the specific surface area and the electric conductivity of the cathode active material precursor is caused by the increase of the electric conductivity of the cathode active material.

[ Experimental Example  4] Evaluation of electrochemical performance of secondary battery - Evaluation of output characteristics

The electrochemical performance was evaluated using the lithium secondary batteries manufactured in Example 1 and Comparative Example 1, respectively.

At this time, the electrochemical performance evaluation was carried out in a voltage range of 3.0 to 4.25 V, charged to 0.2 C, and discharged at a high rate of 0.2 C and 3 C, respectively, and the output of the battery was measured.

Output characteristics [3.0C / 0.2C,%] Comparative Example 1 85.75 Example 1 87.13

As can be seen from the above Table 3, the battery of Example 1 having an anode made from an electroconductive cathode active material precursor containing an oxide system and a hydroxide system was prepared in the same manner as in Comparative Example 1 having an anode made using an insulating hydroxide- 1, the output characteristics of the battery were improved (see Table 3).

Claims (14)

Complex transition metal hydroxides; And
A composite transition metal oxide,
Lt; RTI ID = 0.0 &gt; mS / cm. &Lt; / RTI &gt; The method according to claim 1,
Wherein the specific surface area measured by the nitrogen adsorption BET method is in the range of 50 to 200 m ² / g. The method according to claim 1,
Wherein the precursor has a pore volume less than 10 nm in the range of 10 ^-3 to 5 10 ^-2 cm ³ / g · nm per particle weight. The method according to claim 1,
Wherein the complex transition metal hydroxide and the complex transition metal oxide are mixed with each other or are in a solid solution form. The method according to claim 1,
A positive electrode active material precursor represented by the following formula (1)
[Chemical Formula 1]
(MOx) _A (M (OH) ₂ ) _B
In this formula,
M is Ni _a Co _b M ' _c ,
M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a Group 17 element, a transition metal,
1? X? 1.5, 0.6? A <1.0, 0? B? 0.4, 0? C? 0.4, a + b + c =
A + B = 1, 0.5? A < 1.0 and 0 < B? 0.5. 6. The method of claim 5,
Wherein M 'is at least one element selected from the group consisting of Al, Mn, Zr, W, Ti, Mg, Sr, Ba, Ce, Hf, F, P, S, La and Y. 6. The method of claim 5,
Wherein A is not less than 0.6 and not more than 1.0, and B is more than 0 and not more than 0.4. A cathode active material produced by using the cathode active material precursor according to any one of claims 1 to 7 and a lithium precursor. 9. The method of claim 8,
Wherein the nickel (Ni) content in the total transition metal is 60% or more. 10. The method of claim 9,
Lt; RTI ID = 0.0 &gt; mS / cm. &Lt; / RTI &gt; A process for producing the precursor of a cathode active material according to claim 1, comprising heat-treating the complex transition metal hydroxide represented by the following formula (2) at a temperature of 200 to 500 ° C for 0.5 to 10 hours:
(2)
M (OH) ₂
In this formula,
M is Ni _a Co _b M ' _c ,
M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a Group 17 element, a transition metal,
0.6? A <1.0, 0? B? 0.4, 0? C? 0.4, a + b + c = 12. The method of claim 11,
Wherein the positive electrode active material precursor is represented by the following Formula 1:
[Chemical Formula 1]
(MOx) _A (M (OH) ₂ ) _B
In this formula,
M is Ni _a Co _b M ' _c ,
M 'is at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a Group 17 element, a transition metal,
1? X? 1.5, 0.6? A <1.0, 0? B? 0.4, 0? C? 0.4, a + b + c =
A + B = 1, 0.5? A < 1.0 and 0 < B? 0.5. 13. The method of claim 12,
In the above formula (1), the ratio of A to B is
(i) changing the concentration of oxygen during heat treatment,
(ii) using an oxidizing agent, or
(iii) by applying both of them. &lt; Desc / Clms Page number 13 &gt; 14. The method of claim 13,
The oxidizing agent is selected from the group consisting of KMnO ₄ , H ₂ O _2, Na ₂ O ₂ , FeCl ₃ , CuSO ₄ , CuO, PbO ₂ , MnO ₂ , HNO ₃ , KNO ₃ , K ₂ Cr ₂ O ₇ , CrO ₃ , P ₂ O _{5 ,} H ₂ SO ₄ , K ₂ S ₂ O ₈ , halogen, and C ₆ H ₅ NO ₂ .

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