KR101871919B1 - Positive active material for lithium secondary battery and method of preparing the same and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a lithium-containing compound; And a surface treatment layer formed on the lithium-containing compound, wherein the surface treatment layer comprises at least two compounds selected from the group consisting of Al (OH) ₃ , B-containing compounds and Si- A cathode active material, a method for producing the same, and a lithium secondary battery comprising the same.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the lithium secondary battery.

The present invention relates to a cathode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery comprising the same.

Lithium secondary batteries are the most popular energy devices in IT, electric vehicles and energy storage devices. Lithium rechargeable batteries have made remarkable progress over the past 25 years since Sony first commercialized them in 1990. The first application area was limited to the mobile field such as notebook computer, but recently it has been continuously developed as application fields are expanded not only for electric vehicles but also for large-scale energy storage devices. Particularly, due to the issue of environment friendliness and efficiency, electric automobile field and energy storage device field are expanding into new business fields, and the application field of lithium secondary battery is rapidly expanding.

Although the lithium secondary battery used in the first IT field could be applied only when the lifetime and the capacity target were attained, the application of the lithium secondary battery to the electric vehicle and the energy storage device field expanded, and the demand for the performance improvement of the lithium secondary battery continuously . In this field, it is possible to apply not only the target according to the capacity and the life characteristic but also the thermal stability, the reliability and the price to the very high target.

The cathode active materials of lithium secondary batteries have developed remarkably over the last 25 years. Lithium-cobalt compound [LiCoO _2] Start a lithium-manganese-based compound [LiMn ₂ O _4], a lithium-nickel-cobalt-manganese-based compound _{[LiNi x Co y Mn z O} 2, x: y: z = 1 Nickel-cobalt-aluminum-based compounds, which were continuously developed for capacity up to 1: 1, 4: 3: 3, 5: 2: 3, 6: 2: 2, 8: [LiNi _x Co _y Al _z O ₂ , x = 80, 83, 85, 88] has been continuously being developed and its application range is continuously expanding. In general, the cathode active material is doped with one or more transition metals to strengthen the bulk structure in the core layer to form a core layer having a stabilized bulk structure and subjected to surface treatment to further improve lifetime characteristics, thermal stability, reliability and the like do. For example, in the case of a lithium-cobalt compound, a core layer in which a bulk structure of LiCo _{1 -xy} M ' _x M " _y O ₂ type is stabilized is used, and a metal such as M' = Mg, M" . The lithium-cobalt compound having a stabilized bulk structure is subjected to surface treatment in order to improve lifetime characteristics, thermal stability, reliability and the like. The development of such a doping technique is applied not only to lithium-cobalt compounds but also to all the cathode active materials such as lithium-manganese compounds, lithium-nickel-cobalt-manganese compounds and lithium-nickel-cobalt-aluminum compounds.

There are two methods for improving the capacity of a lithium secondary battery. One is a method of developing a lithium secondary battery by applying a high capacity cathode active material and the other is a method of increasing the charging voltage of the lithium secondary battery to increase its capacity. In the former case, a high capacity cathode active material was developed and applied in the direction of lithium-cobalt compound [discharge capacity 160 mAh / g] → LNCM [discharge capacity ~ 180 mAh / g] → LNCA [discharge capacity ~ 200 mAh / g] It is the direction to develop the battery. The second case is the development direction for developing a high capacity lithium secondary battery while using the same type of cathode active material. Since the general cathode active material has a layered structure except for the lithium-manganese-based compound, the discharge capacity increases when the charging voltage is increased. For example, in the case of the lithium-cobalt compound, the discharge capacity is about 160 mAh / g when the battery is charged at 4.3 V and discharges. However, when the battery is charged at 4.4 V and discharged, the battery is charged at 170 mAh / g. < / RTI > That is, in recent years, a high capacity lithium secondary battery has been developed by developing a technique of charging a lithium secondary battery at a high voltage using the characteristics of the layered positive electrode active material. However, when the charging voltage of the positive electrode active material is increased to evaluate the performance, the discharge capacity increases as the charging voltage increases. On the contrary, the lifetime characteristics are significantly lowered. Also, as the charging voltage increases, A characteristic directly correlated with the safety of the battery] exhibits a characteristic that becomes very poor. Also, this phenomenon is more serious at high temperature than at room temperature. That is, when the charging voltage is increased to charge the battery at a high voltage and the lithium secondary battery is used, the lifetime characteristics, thermal stability, and reliability of the lithium secondary battery deteriorate at a temperature higher than room temperature.

The present invention relates to a lithium-containing compound; And a surface treatment layer formed on the lithium-containing compound, wherein the surface treatment layer comprises at least two compounds selected from the group consisting of Al (OH) ₃ , B-containing compounds and Si- A cathode active material, and the like.

However, the technical problem to be solved by the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

The present invention relates to a lithium-containing compound; And a surface treatment layer formed on the lithium-containing compound, wherein the surface treatment layer comprises at least two compounds selected from the group consisting of Al (OH) ₃ , B-containing compounds and Si- Thereby providing a cathode active material.

The lithium-containing compound may include at least one compound selected from the group consisting of a lithium-nickel-cobalt-manganese compound, a lithium-nickel-cobalt-aluminum compound and a lithium-cobalt compound.

The lithium-containing compound may be a lithium-nickel-cobalt-manganese-based compound represented by the following formula (1)

[Chemical Formula 1]

Li _x Ni _1-yza Co _y Mn _z M _{aa 2}

Wherein M is at least one selected from the group consisting of Mg, Ti, Al and Zr, A is at least one selected from the group consisting of O, F, S and P. < / RTI >

Wherein the surface treatment layer comprises Al (OH) ₃ , a B-containing compound and a Si-containing compound; Al (OH) ₃ And B-containing compounds; Al (OH) ₃ and Si-containing compounds; Or B-containing compounds and Si-containing compounds.

Those containing the above-described surface treatment layer containing Al (OH) _3, B- Si- containing compound and a compound, Al (OH) ₃ 100 parts by weight of the preparation, B- containing compound contained 20 parts by weight to 100 parts by weight of Si- 30 parts by weight to 100 parts by weight of the compound.

When the 50% cumulative mass particle size distribution diameter in the particle distribution of the cathode active material is D50, the D50 may be 5 to 7 mu m.

In one embodiment of the present invention, there is provided a method of preparing a lithium-containing compound, comprising: (a) preparing a lithium-containing compound; (b) preparing a surface treatment solution comprising at least two solutions selected from the group consisting of Al (OH) ₃ solution, B-containing compound solution and Si-containing compound solution; And (c) adding the lithium-containing compound prepared in the step (a) to the surface-treating solution prepared in the step (b), followed by mixing and drying the cathode active material for the lithium secondary battery.

The Al (OH) ₃ solution, the B-containing compound solution or the Si-containing compound solution in the step (b) may be water or an alcohol in an amount of 95% or less.

In step (b), the concentration of each solute in the Al (OH) ₃ solution, the B-containing compound solution or the Si-containing compound solution may be 1 to 1000 ppm.

In the step (c), the weight ratio of the surface treatment solution and the lithium-containing compound may be 0.5: 1 to 1: 3.

In the step (c), mixing and drying may be performed simultaneously.

In the step (c), mixing and drying may be performed at a temperature of 50 ° C to 150 ° C for 1 hour to 10 hours.

(d) further heat-treating at a temperature higher than the drying temperature in the step (c).

The additional heat treatment may be performed at a temperature of 100 ° C to 700 ° C for 1 hour to 10 hours.

In another embodiment of the present invention, there is provided a lithium secondary battery comprising the cathode active material.

The cathode active material for a lithium secondary battery according to the present invention comprises a lithium-containing compound; And a surface treatment layer formed on the lithium-containing compound, wherein the surface treatment layer comprises at least two compounds selected from the group consisting of Al (OH) ₃ , B-containing compounds and Si- As a result, surface treatment of the lithium-containing compound with a plurality of compounds on the lithium-containing compound has an effect of improving lifetime characteristics at high temperature and normal temperature under high-voltage conditions, improving thermal stability, and improving swelling properties.

Figure 1 is a graph showing the thermal properties of B-containing compounds.
FIG. 2 is a photograph showing a device capable of simultaneously performing mixing and drying in the method for producing a cathode active material according to the present invention.
3 is a SEM photograph of the cathode active material according to the present invention.
4 is a graph showing the XRD crystal structure of the cathode active material according to the present invention.
FIG. 5 is a graph showing the normal temperature lifetime characteristics of a coin cell and a full cell including a cathode active material according to the present invention.
6 is a graph showing high temperature lifetime characteristics of a coin cell and a full cell including a cathode active material according to the present invention.
7 is a graph showing the capacity retention rate according to the change of the C-rate of the coin cell including the cathode active material according to the present invention.
8 is a graph showing the thermal stability of a coin cell including a cathode active material according to the present invention.
9 is a graph showing swelling characteristics of a full cell including a cathode active material according to the present invention.
10 is a graph comparing high temperature lifetime characteristics of a coin cell including a cathode active material according to the present invention depending on whether or not a specific element is doped into the lithium containing compound.
FIG. 11 is a graph comparing high-output characteristics according to the C-rate change of a full cell including a cathode active material according to the present invention, according to a specific element doping amount of the lithium-containing compound.

In recent years, lithium secondary batteries have been widely applied not only to IT but also to electric vehicles and energy storage devices. At this time, the battery life of the lithium rechargeable battery for IT was about 300 times, but the lithium rechargeable battery for the electric vehicle had to satisfy the battery life of about 1,000 to 2,000 times at the high temperature and the lithium rechargeable battery for the energy storage device In case of 10 years use time should be guaranteed.

The present inventors have studied a surface treatment technology of a cathode active material to improve lifetime and reliability characteristics of a conventional lithium secondary battery so as to be applicable not only to the IT field but also to electric automobile and energy storage device field. It is possible to improve the lifetime characteristics of the lithium secondary battery under high voltage and high temperature conditions, and completed the present invention.

Hereinafter, the present invention will be described in detail.

The present invention relates to a lithium-containing compound; And a surface treatment layer formed on the lithium-containing compound, wherein the surface treatment layer comprises at least two compounds selected from the group consisting of Al (OH) ₃ , B-containing compounds and Si- Thereby providing a cathode active material.

The lithium-containing compound corresponds to the core layer of the positive electrode active material, and includes at least one compound selected from the group consisting of a lithium-nickel-cobalt-manganese compound, a lithium-nickel-cobalt-aluminum compound, and a lithium- . Since the lithium-containing compounds have a layered structure, when the charging voltage is increased, the discharge capacity increases and the lifetime characteristics of the lithium secondary battery deteriorate. In particular, the lithium-containing compound is preferably a lithium-nickel-cobalt-manganese-based compound having a nickel content of 30 to 90% or a lithium-nickel-cobalt-aluminum-based compound having a nickel content of 80 to 88% Do not. At this time, there is a problem that the higher the nickel content is, the lower the thermal stability, and a surface treatment technique is also required to improve the nickel content.

Specifically, the lithium-containing compound may be a lithium-nickel-cobalt-manganese-based compound represented by the following Formula 1:

[Chemical Formula 1]

Li _x Ni _1-yza Co _y Mn _z M _{aa 2}

Wherein M is at least one selected from the group consisting of Mg, Ti, Al and Zr, A is at least one selected from the group consisting of O, F, S and P. < / RTI >

Specifically, the M is doped, and when the M is doped into the lithium-containing compound, the lithium secondary battery has an effect of improving high-temperature lifetime characteristics under a high voltage condition.

At this time, it is preferable that 0.001? A? 0.02 in case of single doping of M, and 0.001? A? 0.04 in case of complex doping of M, but it is not limited thereto. By controlling the amount of M doping in the lithium-containing compound as described above, the lithium secondary battery can secure a high output characteristic particularly at a high C-rate.

Wherein the surface treatment layer comprises Al (OH) ₃ , a B-containing compound and a Si-containing compound; Al (OH) ₃ and B-containing compounds; Al (OH) ₃ And Si-containing compounds; Or B-containing compounds and Si-containing compounds. That is, since the surface treatment layer includes a plurality of compounds, the lithium secondary battery has an effect of improving high-temperature and normal-temperature lifetime characteristics, improving thermal stability, and improving swelling characteristics under high voltage conditions.

Specifically, in the present invention, Al (OH) ₃ may be contained as one of a plurality of compounds for surface treatment on the lithium-containing compound. The Al-containing compound is included to improve the structural stability of the cathode active material and serves to strengthen the bonding structure by strengthening the bond between metal and oxygen. Particularly, among Al-containing compounds, Al (OH) ₃ is particularly preferable because it can stabilize the crystal structure and reduce the surface resistance of the cathode active material.

Further, in the present invention, one of a plurality of compounds for surface treatment on the lithium-containing compound may contain a B-containing compound. The B-containing compound is used for improving the thermal stability of a lithium secondary battery. The B-containing compound is composed of B ₂ O ₃ , HB (OH) ₂ and H ₃ BO ₃ , which exhibit heat absorbing properties at about 160 to 200 ° C. And most preferably HB (OH) ₂ , but is not limited thereto. In this case, HB (OH) ₂ can be obtained by dissolving B ₂ O ₃ in water or ethanol and then heat-treated at about 100 ° C., and HB (OH) ₂ absorbs heat at about 200 ° C. .

Figure 1 is a graph showing the thermal properties of B-containing compounds.

As shown in FIG. 1, the DSC analysis shows that the B-containing compound exhibits a characteristic of absorbing heat at a temperature of about 160 to 200 ° C. When the compound is included as one of a plurality of compounds for surface treatment on the lithium compound, It is possible to greatly enhance the thermal stability.

In the present invention, one of a plurality of compounds for surface treatment on the lithium-containing compound may contain an Si-containing compound. The important reason why the lifespan characteristics of the lithium secondary battery is rapidly deteriorated at high temperature is that HF generated by the reaction between the electrolytic solution and the water in the electrolytic solution attacks the metal components (Ni, Co, Mn, etc.) to be. At this time, since the Si-containing compound is excellent in reactivity with HF, it is possible to prevent the reaction between the lithium-containing compound and HF. Specifically, the Si-containing compound may be Si or SiO ₂ .

In other words, when the surface treatment layer contains both Al (OH) ₃ , B-containing compound and Si-containing compound, it is possible to stabilize the crystal structure, to secure both low surface resistance, thermal stability, .

Those containing the above-described surface treatment layer containing Al (OH) _3, B- Si- containing compound and a compound, Al (OH) ₃ 100 parts by weight of the preparation, B- containing compound contained 20 parts by weight to 100 parts by weight of Si- 30 parts by weight to 100 parts by weight of the compound.

When the surface treatment layer contains Al (OH) ₃ and a B-containing compound, it may include 20 to 100 parts by weight of the B-containing compound with respect to 100 parts by weight of Al (OH) ₃ .

When the surface treatment layer contains Al (OH) ₃ and a Si-containing compound, it may include 30 to 100 parts by weight of the Si-containing compound with respect to 100 parts by weight of Al (OH) ₃ .

When the surface treatment layer contains a B-containing compound and a Si-containing compound, the surface treatment layer may include 50 to 200 parts by weight of the Si-containing compound, based on 100 parts by weight of the B-containing compound.

When the 50% cumulative mass particle size distribution diameter in the particle distribution of the positive electrode active material is D50, the minor particle having a D50 of 5 to 7 占 퐉 is a major particle having a D50 of 11 to 13 占 퐉, But is not limited thereto.

The present invention also provides a method for preparing a lithium-containing compound, comprising: (a) preparing a lithium-containing compound; (b) Al (OH) ₃ Preparing a surface treatment solution containing at least two or more solutions selected from the group consisting of a solution, a B-containing compound solution and a Si-containing compound solution; And (c) adding the lithium-containing compound prepared in the step (a) to the surface-treating solution prepared in the step (b), followed by mixing and drying the cathode active material for the lithium secondary battery.

First, in order to prepare a positive electrode active material for a lithium secondary battery, a lithium-containing compound is prepared (step (a)). The lithium-containing compound is as described above.

Next, in order to prepare a cathode active material for a lithium secondary battery, Al (OH) ₃ At least two solutions selected from the group consisting of a solution, a B-containing compound solution and a Si-containing compound solution are prepared (step (b)).

The Al (OH) ₃ solution, the B-containing compound solution or the Si-containing compound solution may be water or an alcohol having a content of 95% or less. When a high-purity alcohol having a purity of more than 95% is used as a solvent, there is a problem that the lifetime and reliability characteristics of the lithium secondary battery are not improved. In the present invention, a B ₂ O ₃ aqueous solution is used as the B- B ₂ O ₃ was dissolved in water and then heat-treated at about 100 ° C to obtain HB (OH) ₂ as a B-containing compound.

The concentration of each solute in the Al (OH) ₃ solution, the B-containing compound solution or the Si-containing compound solution may be 1 to 1000 ppm. At this time, the concentration of each solute in the Al (OH) ₃ solution, the B-containing compound solution, and the Si-containing compound solution is maintained at 1 to 1000 ppm so that the cost of the lithium secondary battery It has the advantage of maximizing performance.

(C) adding the lithium-containing compound prepared in the step (a) to the surface treatment solution prepared in the step (b), and then mixing and drying the lithium-containing compound A method for producing a cathode active material for a lithium secondary battery is provided (step (c)).

The weight ratio of the surface treatment solution and the lithium-containing compound is preferably 0.5: 1 to 1: 3, and is not limited thereto. If the weight ratio of the surface treatment solution to the lithium-containing compound is less than 0.5: 1, the surface treatment solution may not be uniformly treated due to the lack of the surface treatment solution. If it exceeds 3, it takes a long time to dry due to excessive surface treatment solution, which is a problem in economy.

The mixing and drying can be performed simultaneously. In order to perform mixing and drying at the same time, the apparatus according to Fig. 2 can be used. The apparatus is characterized in that it is capable of carrying out surface treatment and simultaneously drying.

Specifically, the mixing and drying is preferably performed at a temperature of 50 ° C to 150 ° C for 1 hour to 10 hours, but is not limited thereto. In this case, mixing and drying are performed at the temperatures within the above range, thereby minimizing facility investment and simplifying the process.

Alternatively, in order to produce a cathode active material for a lithium secondary battery, (d) the step (c) may further include an additional heat treatment at a temperature higher than the drying temperature.

Specifically, the additional heat treatment is preferably performed at a temperature of 100 ° C to 700 ° C for 1 hour to 10 hours, but is not limited thereto. At this time, since the additional heat treatment is performed for the temperature and time in the above range, there is an economical advantage by performing additional heat treatment at a relatively low temperature for a short time.

The present invention also provides a lithium secondary battery comprising the cathode active material.

Specifically, a cathode comprising the cathode active material, the conductive material, and the binder; A negative electrode comprising a negative electrode active material; And a lithium secondary battery including the electrolyte. The lithium secondary battery includes a positive electrode, a negative electrode, and a separator. The separator may be a polyolefin separator commonly known as a separator for insulating the electrodes between the positive and negative electrodes, or an organic composite layer formed on the olefinic material A composite membrane, and the like, and is not particularly limited.

A middle or large-sized battery module or a battery pack including a plurality of the lithium secondary batteries electrically connected. The middle or large-sized battery module or the battery pack includes a power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric truck; Electric commercial vehicle; Or a power storage system, as shown in FIG.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the following examples.

[ Example ]

Example  One

Ni _{0 . 5} Co _{0 . 2} Mn _{0 .3} (OH) ₂ precursor [Manufacturer: Brunp] and Li ₂ CO ₃ [Manufacturer: Rockwood] the Li / Me (= Ni + Co + Mn) = 1.03 ~ 1.05, after mixing on the conditions, length 40m RHK by using a continuous heat treatment in an air atmosphere at 910 ~ 930 ℃ for 10 hours Li _x Ni _{0. 5} Co _{0 . 2} Mn _{0 . 3} O ₂ powder was once prepared. Using an air classifier, Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ powder was pulverized and then sieved at 400 mesh to prepare a lithium-containing compound (L-1).

Al (OH) ₃ aqueous solution of [Manufacturer: Snow Chemical (China)] (Al (OH) ₃ concentration (w / w) = 1,000ppm) , B 2 O 3 aqueous solution of [Manufacturer: Junsei] (B ₂ O ₃ concentration (w (w / w) = 300 ppm) and an n-SiO ₂ aqueous solution (manufacturer: Aladdin, n-SiO ₂ concentration (w / w) = 500 ppm) ).

Thereafter, using the apparatus shown in Fig. 1, lithium-containing (S-1) was added to the surface treatment solution (S-1) until the weight ratio of the surface treatment solution (S-1) and the lithium- Compound (L-1) was added while stirring little by little, and further stirring was performed for about 1 hour after addition was completed. Thereafter, they were mixed and dried at 100 DEG C for about 3 to 5 hours. Thereafter, the resultant was further heat-treated at 500 ° C for about 5 hours, and then sieved at 400 mesh to prepare a cathode active material for a lithium secondary battery.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  2

Al (OH) ₃ aqueous solution of [Manufacturer: Snow Chemical (China)] (Al (OH) ₃ concentration (w / w) = 1,000ppm) , B 2 O 3 aqueous solution of [Manufacturer: Junsei] (B ₂ O ₃ concentration (w (w / w) = 500 ppm) and an n-SiO ₂ aqueous solution (manufacturer: Aladdin, n-SiO ₂ concentration (w / w) = 300 ppm) ).

Thereafter, using the apparatus shown in Fig. 1, the surface treatment solution (S-1) was added until the weight ratio of the surface treatment solution (S-2) and the lithium containing compound -2), the lithium-containing compound (L-1) was added little by little and further stirred for about 1 hour after addition was completed. Thereafter, the resultant was mixed and dried at 100 ° C for about 4 to 6 hours. After further heat treatment at 300 ° C for about 5 hours, the cathode active material for a lithium secondary battery was finally prepared by sieving at 400 mesh.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  3

Al (OH) ₃ aqueous solution of [Manufacturer: Snow Chemical (China)] (Al (OH) ₃ concentration (w / w) = 500ppm) , B 2 O 3 aqueous solution of [Manufacturer: Junsei] (B ₂ O ₃ concentration (w / w) = 500ppm) and n-SiO ₂ solution [Manufacturer: Aladdin] (n-SiO ₂ concentration (w / w) = 500ppm) respectively, are manufactured and then, mixed with each other in the same weight ratio of the surface treatment solution (S-3) .

Thereafter, the surface treatment solution (S-3) and the lithium-containing compound (L-1) prepared in Example 1 were mixed until the weight ratio of the surface treatment solution (S- -3), the lithium-containing compound (L-1) was added little by little and further stirred for about 1 hour after the addition was completed. Thereafter, they were mixed and dried at 100 DEG C for about 3 to 5 hours. Thereafter, the resultant was further heat-treated at 700 ° C for about 5 hours, and then sieved at 400 mesh to finally produce a cathode active material for a lithium secondary battery.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  4

Al (OH) ₃ aqueous solution of [Manufacturer: Snow Chemical (China)] (Al (OH) ₃ concentration (w / w) = 500ppm) , B 2 O 3 aqueous solution of [Manufacturer: Junsei] (B ₂ O ₃ concentration (w / w) = 100 ppm) and an n-SiO ₂ aqueous solution (manufacturer: Aladdin, n-SiO ₂ concentration (w / w) = 500 ppm) .

2, the surface treatment solution (S-4) and the lithium-containing compound (L-1) prepared in Example 1 were added until the weight ratio of the surface treatment solution -3), the lithium-containing compound (L-1) was added little by little and further stirred for about 1 hour after the addition was completed. Thereafter, they were mixed and dried at 100 DEG C for about 3 to 5 hours. Thereafter, the resultant was further heat-treated at 500 ° C for about 5 hours, and sieved at 400 mesh to prepare a cathode active material for a lithium secondary battery. The SEM photograph of the cathode active material was shown in FIG. 3 (a).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  5

Ni _{0 . 6} Co _{0 . 2} Mn _{0 .2} (OH) ₂ precursor [Manufacturer: Brunp] and Li ₂ CO ₃ [Manufacturer: Rockwood] the Li / Me (= Ni + Co + Mn) = 1.03 ~ 1.05, after mixing on the conditions, length 40m RHK continuous furnace for 10 hours at 860 ~ 880 ℃ under air atmosphere to obtain Li _x Ni _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ powder was once prepared. Using an air classifier, Li _x Ni _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ powder was pulverized and then sieved at 400 mesh to prepare a lithium-containing compound (L-2).

Thereafter, a cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 1 except that the lithium-containing compound (L-2) was used instead of the lithium-containing compound (L-1) 3 (b).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  6

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 2 except that the lithium containing compound (L-2) prepared in Example 5 was used in place of the lithium containing compound (L-1) SEM photographs are shown in Fig. 3 (c).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  7

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 3, except that the lithium-containing compound (L-2) prepared in Example 5 was used in place of the lithium-containing compound (L-1).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  8

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 4, except that the lithium-containing compound (L-2) prepared in Example 5 was used in place of the lithium-containing compound (L-1).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  9

Ni _{0 . 7} Co _{0 .} Of the was mixed at Li / Me (= Ni + Co + Mn) = 1.03 ~ 1.05 condition, 40m length ₁₅ Mn _{0 .15} (OH) ₂ precursor [Manufacturer:: Brunp; and Li ₂ CO ₃ [Rockwood manufacturer; RHK by using a continuous heat treatment at 780 ~ 800 ℃ and oxygen atmosphere for 10 hours Li _x Ni _{0. 7} Co _{0 . 15} Mn _{0 . 15} O ₂ powder was once prepared. Using an air classifier, Li _x Ni _{0 . 7} Co _{0 . 15} Mn _{0 . 15} O ₂ powder was pulverized and then sieved at 400 mesh to prepare a lithium-containing compound (L-3).

Thereafter, a cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 1, except that the lithium-containing compound (L-3) was used instead of the lithium-containing compound (L-1).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  10

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 2, except that the lithium-containing compound (L-3) prepared in Example 9 was used instead of the lithium-containing compound (L-1).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  11

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 3 except that the lithium containing compound (L-3) prepared in Example 9 was used in place of the lithium containing compound (L-1).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  12

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 4 except that the lithium containing compound (L-3) prepared in Example 9 was used instead of the lithium containing compound (L-1).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  13

Al (OH) ₃ aqueous solution of [Manufacturer: Snow Chemical (China)] (Al (OH) ₃ concentration (w / w) = 1,000ppm) and B ₂ O ₃ aqueous solution of [Manufacturer: Junsei] (B ₂ O ₃ concentration (w / w) = 300 ppm) were respectively prepared and mixed with each other at the same weight ratio to prepare a surface treatment solution (S-5).

Thereafter, a cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 1, except that the surface treatment solution (S-5) was used in place of the surface treatment solution (S-1).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  14

Al (OH) ₃ aqueous solution of [Manufacturer: Snow Chemical (China)] (Al (OH) ₃ concentration (w / w) = 500ppm) and n-SiO ₂ solution [Manufacturer: Aladdin] (n-SiO ₂ concentration (w / w) = 300 ppm) were respectively prepared and then mixed with each other at the same weight ratio to prepare a surface treatment solution (S-6).

Thereafter, a cathode active material for a lithium secondary battery was prepared in the same manner as in Example 2, except that the surface treatment solution (S-6) was used in place of the surface treatment solution (S-2).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  15

B ₂ O ₃ aqueous solution of [Manufacturer: Junsei] (B ₂ O ₃ concentration (w / w) = 500ppm) and n-SiO ₂ solution [Manufacturer: Aladdin] (n-SiO ₂ concentration (w / w) = 500ppm) the And then mixed with each other at the same weight ratio to prepare a surface treatment solution (S-7).

Thereafter, a cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 3, except that the surface treatment solution (S-7) was used in place of the surface treatment solution (S-2).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Example  16

Ni _{0 . 8} Co _{0 . 1 0 .1} Mn (OH) ₂ precursor [Manufacturer: Brunp] and Li ₂ CO ₃ [Manufacturer: Rockwood] the Li / Me (= Ni + Co + Mn) = 1.03 was mixed in condition, RHK sequence of length 40m And then heat-treated at 760 ° C for 10 hours in an oxygen atmosphere using Li _x Ni _{0 . 8} Co _{0 . 1} Mn _{0 . 1} O ₂ powder was once prepared. Using an air classifier, Li _x Ni _{0 . 8} Co _{0 . 1} Mn _{0 . 1} O ₂ powder was pulverized and then sieved at 400 mesh to prepare a lithium-containing compound (L-4).

Thereafter, the same procedure as in Example 1 was repeated except that the lithium-containing compound (L-4) was used instead of the lithium-containing compound (L-1) .

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 5 to 7 μm.

Example  17

Using 1000 ppm of Al ₂ O _{3 and} 1000 ppm of ZrO ₂ as a doping material, Li _x Ni _{0 . 8} Co _{0 . 1} Mn _{0 . A} cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 16 except that Li _x Ni _0.8 Co _0.1 Mn _0.08 Al _0.01 Zr _0.01 O ₂ powder was prepared instead of ₁ O ₂ powder.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 5 to 7 μm.

Example  18

Using 2000 ppm of Al ₂ O ₃ and 1000 ppm of ZrO ₂ as a doping material, Li _x Ni _{0 . 8} Co _{0 . 1} Mn _{0 . A} cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 16, except that Li _x Ni _0.8 Co _0.1 Mn _0.07 Al _0.02 Zr _0.01 O ₂ powder was prepared instead of ₁ O ₂ powder.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 5 to 7 μm.

Example  19

Using 3000 ppm of Al ₂ O ₃ and 1000 ppm of ZrO ₂ as a doping material, Li _x Ni _{0 . 8} Co _{0 . 1} Mn _{0 . A} cathode active material for a lithium secondary battery was finally prepared in the same manner as in Example 16, except that Li _x Ni _0.8 Co _0.1 Mn _0.06 Al _0.03 Zr _0.01 O ₂ powder was prepared instead of ₁ O ₂ powder.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 5 to 7 μm.

Comparative Example  One

The lithium-containing compound (L-1) prepared in Example 1 was used as a cathode active material for a lithium secondary battery.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  2

The lithium-containing compound (L-2) prepared in Example 5 was used as a cathode active material for a lithium secondary battery, and a SEM photograph thereof was shown in FIG. 3 (d).

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  3

The lithium-containing compound (L-3) prepared in Example 9 was used as a cathode active material for a lithium secondary battery.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  4

Commercial LiCoO ₂ was prepared from the lithium-containing compound (L-4) and a B ₂ O ₃ aqueous solution (manufacturer: Junsei) (B ₂ O ₃ concentration (w / w) = 300 ppm) was used as the surface treatment solution (S- Prepared.

Thereafter, using the apparatus shown in Fig. 1, the surface treatment solution (S-7) was added to the surface treatment solution (S-7) until the weight ratio of the surface treatment solution (S-7) and the lithium- Compound (L-4) was added while stirring little, and further stirring was carried out for about 1 hour after addition was completed. Thereafter, the mixture was mixed and dried at 100 ° C for about 3 to 6 hours, and then sieved at 400 mesh to prepare a cathode active material for a lithium secondary battery.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  5

The cathode active material for a lithium secondary battery was finally prepared in the same manner as in Comparative Example 4, except that the mixture was dried at 300 ° C and dried.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  6

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Comparative Example 4, except that the mixture was dried at 500 ° C and dried.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  7

A cathode active material for a lithium secondary battery was finally prepared in the same manner as in Comparative Example 4, except that the mixture was mixed at 700 ° C and dried.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  8

UM NCM111 manufactured by Umicore was prepared as a cathode active material for a lithium secondary battery.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

Comparative Example  9

A UM NCM 523 product manufactured by Umicore was prepared as a cathode active material for a lithium secondary battery.

The final prepared cathode active material was analyzed by a particle size analyzer and found to have a D50 of 11 to 13 탆.

The lithium-containing compound Surface treatment solution Mixing and drying temperature
(° C) Additional heat treatment temperature
(° C) Furtherance Heat treatment temperature
(° C) Al (OH) ₃
density
(ppm) B ₂ O ₃
density
(ppm) n-SiO ₂
density
(ppm) Example 1 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 1,000 300 500 100 500 Example 2 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 1,000 500 300 100 300 Example 3 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 500 500 500 100 700 Example 4 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 500 100 500 100 500 Example 5 Li _x Ni _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ 860 to 880 1,000 300 500 100 500 Example 6 Li _x Ni _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ 860 to 880 1,000 500 300 100 300 Example 7 Li _x Ni _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ 860 to 880 500 500 500 100 700 Example 8 Li _x Ni _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ 860 to 880 500 100 500 100 500 Example 9 Li _x Ni _0.7 Co _0.15 Mn _0.15 O ₂ 780 to 800 1,000 300 500 100 500 Example 10 Li _x Ni _0.7 Co _0.15 Mn _0.15 O ₂ 780 to 800 1,000 500 300 100 300 Example 11 Li _x Ni _0.7 Co _0.15 Mn _0.15 O ₂ 780 to 800 500 500 500 100 700 Example 12 Li _x Ni _0.7 Co _0.15 Mn _0.15 O ₂ 780 to 800 500 100 500 100 500 Example 13 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 1,000 300 - 100 500 Example 14 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 500 - 300 100 300 Example 15 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 - 500 500 100 700 Example 16 Li _x Ni _{0 . 8} Co _{0 . 1} Mn _{0 . 1} O ₂ 760 1,000 300 500 100 400 Example 17 Li _x Ni _0.8 Co _0.1 Mn _0.08 Al _0.01 Zr _0.01 O ₂ 760 1,000 300 500 100 400 Example 18 Li _x Ni _0.8 Co _0.1 Mn _0.07 Al _0.02 Zr _0.01 O ₂ 760 1,000 300 500 100 400 Example 19 Li _x Ni _0.8 Co _0.1 Mn _0.06 Al _0.03 Zr _0.01 O ₂ 760 1,000 300 500 100 400 Comparative Example 1 Li _x Ni _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ 910-930 - - - - - Comparative Example 2 Li _x Ni _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ 860 to 880 - - - - - Comparative Example 3 Li _x Ni _0.7 Co _0.15 Mn _0.15 O ₂ 780 to 800 - - - - - Comparative Example 4 LiCoO ₂ - - 300 - 100 - Comparative Example 5 LiCoO ₂ - - 300 - 300 - Comparative Example 6 LiCoO ₂ - - 300 - 500 - Comparative Example 7 LiCoO ₂ - - 300 - 700 - Comparative Example 8 - - - - - - - Comparative Example 9 - - - - - - -

Experimental Example

(1) The positive electrode active material XRD  Crystal structure

The XRD crystal structure of the cathode active material finally prepared in Example 2 and Comparative Example 1 was analyzed, and the results are shown in FIG.

As shown in FIG. 4, when the surface was treated with a plurality of compounds as in Example 2, it was confirmed that a low angle shift occurred as compared with the case where the surface treatment was not performed as in Comparative Example 1. This is a phenomenon caused by an increase in the lattice parameter due to the crystal structure due to the surface treatment.

Particularly, in the case of Example 2, since the surface-doping of the surface-treated pepper occurs due to the heat treatment, it is confirmed that the lattice constant of the unit cell of the crystal structure increases and low angular movement occurs.

(2) Evaluation of life characteristics of coin cell

The cathode active material slurry was prepared using the NMP solvent at a weight ratio of the cathode active material: conductive material: binder of 95: 2.5: 2.5 prepared in Examples and Comparative Examples, and the cathode active material slurry was produced at a density of 3.3 g / Coin cells were prepared in a drying chamber using a Li metal cathode and EC / DMC / DEC [1/1/1] + 1M LiPF ₆ electrolytic solution. Respectively.

After the initial charging / discharging, charging / discharging was carried out under conditions of 4.5 to 3.0 V 1C / 1C (or 0.5C / 0.5C) charge / discharge at 25 ° C to evaluate the normal temperature lifetime characteristics of the coin cell. a) to (d).

After the initial charging / discharging, charging and discharging were performed under conditions of 4.5 to 3.0 V 1C / 1C (or 0.5C / 0.5C) charge / discharge at 45 ° C to evaluate the high temperature lifetime characteristics of the coin cell. (a) to (e).

As shown in FIGS. 5 (a) to 5 (d) and 6 (a) to 6 (e), in the case of surface treatment with a plurality of compounds as in the examples, It was confirmed that the coin cell had excellent characteristics at room temperature and high temperature.

Specifically, it was confirmed that the capacity retention ratio of the coin cell was improved by about 2% after 60 cycles in the case of Examples 1 to 3 and Example 13 compared with Comparative Example 1, and it was confirmed that the coin cell had excellent room temperature lifetime characteristics (See Figs. 5 (a) and 5 (b)).

Further, it was confirmed that the capacity retention ratio of the coin cell after the 80th cycle was improved by about 4% in the case of the examples 1 to 3 compared with the comparative example 1, and in the case of the example 13, It was confirmed that the capacity retention rate was improved by about 0.5%, and it was confirmed that the coin cell had excellent high-temperature lifetime characteristics (see FIGS. 6 (a) and 6 (b)).

In Example 18, it was confirmed that the capacity retention ratio of the coin cell was improved by about 4% after 50 cycles as compared with Example 16, and it was confirmed that the coin cell had excellent high temperature lifetime characteristics (FIG. 10). In the case of Example 16 and Example 18, the 50% cumulative mass particle size distribution diameter in the particle distribution of the cathode active material was D50 < RTI ID = 0.0 > The D50 corresponds to a small particle having a size of 5 to 7 mu m. When such a small particle is used, it can be confirmed that the coin cell has excellent high temperature lifetime characteristics.

(3) Evaluation of lifetime characteristics of full cell

The cathode active material slurry was prepared using the NMP solvent at a weight ratio of the cathode active material: conductive material: binder of 92: 5: 3 prepared in Examples 2 and 13 and Comparative Example 1, and the cathode plate density was 3.3 to 3.4 g / cc , And a square full cell was prepared using a natural graphite cathode and EC / DMC / DEC [1/1/1] + 1M LiPF ₆ electrolyte. Thereafter, initial charging and discharging was performed under 0.1 C / 0.1 C charge / discharge conditions.

After the initial charging / discharging, charging / discharging was carried out at 25 ° C under a condition of 4.2 to 3.0 V of 1 C / 1 C charge / discharge cycle to evaluate the normal temperature lifetime characteristics of the full cell, and the evaluation result is shown in FIG. 5 (e).

After the initial charging / discharging, charging / discharging was performed under the condition of 4.2 to 3.0 V 1 C / 1 C charge / discharge at 45 ° C to evaluate the high-temperature lifetime characteristics of the full cell, and the evaluation result is shown in FIG. 6 (f).

As shown in FIG. 5 (e) and FIG. 6 (f), in the case of surface treatment with a plurality of compounds as in Examples 2 and 13, compared with the case where the surface treatment was not performed as in Comparative Example 1, It was confirmed that the life characteristics were excellent.

(4) Evaluation according to C-rate change of coin cell

A coin cell was prepared by the method described in (2) above using the cathode active material finally prepared in Example 10 and Comparative Example 3. Thereafter, the initial charge and discharge was carried out under the 0.1 C / 0.1 C charge / discharge condition, and the capacity retention rate of the coin cell was measured while changing the C-rate in the order of 0.2C, 0.33C, 0.5C, 1.0C, 3.0C and 5.0C And the results are shown in Fig.

As shown in FIG. 7, it was confirmed that the coin cell had a high capacity retention rate even under the conditions of 3.0C and 5.0C as compared with the comparative example 3 in the case of the example 10.

(5) Evaluation of thermal stability of coin cell

Coin cells were prepared in the same manner as in (2) above, using the cathode active materials prepared in Examples 2, 13 to 15 and Comparative Example 1. Thereafter, the coin cell charged at 4.3 V was disassembled in the drying chamber to separate the electrode plate. About 10 mg of the cathode active material coated on the Al-foil was taken from the separated electrode plate, and DSC analysis was performed using 910 DSC (TA Instrument). The DSC analysis was performed by scanning at a temperature rising rate of 3 DEG C / min in a temperature range of 25 to 300 DEG C in an air atmosphere. The results of the DSC analysis are shown in FIG.

As shown in FIG. 8, it was confirmed that the thermal stability was excellent because the peaks of the heat flux corresponding to the temperature were not higher than those of Comparative Example 1 in Examples 2, 13 to 15.

(6) full cell Swelling  Character rating

Using the cathode active material prepared in Example 2 and Comparative Examples 1, 8 and 9, a full cell was prepared as described in (2) above. Thereafter, the cells were allowed to stand at 60 ° C for 7 days, and then the hot cells were subjected to hot swelling. Then, the cells were cooled to room temperature (25 ° C) and the cells were subjected to cold swelling ) Were compared with each other, and the results are shown in FIG.

As shown in Fig. 9, it was confirmed that the swelling characteristics were improved as compared with Comparative Examples 1, 8 and 9 in the case of Example 2. Particularly, in the case of Example 2, it was confirmed that the effect of the high-temperature swelling was superior in the state of being left at 60 ° C.

(7) Evaluation according to change of full cell C-rate

A full cell was prepared by the method described in (2) above using the cathode active material finally prepared in Examples 18 and 19. Thereafter, initial charging and discharging was performed at 0.1 C / 0.1 C charge / discharge condition, and full-cell high-power characteristics were evaluated while varying the C-rate in the order of 2C and 4C.

As shown in Fig. 11, it was confirmed that discharge was easily occurred in Example 19 as compared with Example 18. The difference in discharge amount was found to be higher at the higher C-rate than at the lower C-rate. Therefore, in order to secure a high output characteristic, it is necessary that the doping amount of a specific element in the lithium-containing compound is controlled.

In the case of Examples 18 and 19, when the 50% cumulative mass particle size distribution diameter in the particle distribution of the cathode active material is D50, the D50 corresponds to a small particle having a size of 5 to 7 占 퐉. When such a small particle is used , And high power characteristics of the full cell.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (15)

A lithium-containing compound; And
And a surface treatment layer formed on the lithium-containing compound,
Wherein the surface treatment layer comprises Al (OH) ₃ , a B-containing compound and a Si-containing compound,
20 to 100 parts by weight of the B-containing compound and 30 to 100 parts by weight of the Si-containing compound, relative to 100 parts by weight of the Al (OH) ₃ ,
Cathode active material for lithium secondary battery.
The method according to claim 1,
The lithium-containing compound includes at least one compound selected from the group consisting of a lithium-nickel-cobalt-manganese compound, a lithium-nickel-cobalt-aluminum compound and a lithium-cobalt compound
Cathode active material for lithium secondary battery.
The method according to claim 1,
The lithium-containing compound is a lithium-nickel-cobalt-manganese-based compound represented by the following formula
Cathode active material for lithium secondary battery:
[Chemical Formula 1]
Li _x Ni _1-yza Co _y Mn _z M _{aa 2}
Wherein M is at least one selected from the group consisting of Mg, Ti, Al and Zr, A is at least one selected from the group consisting of O, F, S and P. < / RTI >
delete delete The method according to claim 1,
When the 50% cumulative mass particle size distribution diameter in the particle distribution of the cathode active material is D50, the D50 is 5 to 7 mu m
Cathode active material for lithium secondary battery.
(a) preparing a lithium-containing compound;
(b) preparing a surface treatment solution comprising an Al (OH) ₃ solution, a B-containing compound solution and a Si-containing compound solution;
(c) adding the lithium-containing compound prepared in step (a) to the surface-treating solution prepared in step (b), mixing and drying the solution at a temperature of 50 ° C to 150 ° C for 1 hour to 10 hours; And
(d) further heat treatment at a temperature of 300 ° C to 700 ° C for 1 hour to 10 hours,
20 to 100 parts by weight of the B-containing compound and 30 to 100 parts by weight of the Si-containing compound, relative to 100 parts by weight of the Al (OH) ₃ ,
(Method for producing positive electrode active material for lithium secondary battery).
8. The method of claim 7,
In the step (b), the Al (OH) ₃ solution, the B-containing compound solution or the Si-containing compound solution may be prepared by using water or an alcohol having not more than 95%
(Method for producing positive electrode active material for lithium secondary battery).
8. The method of claim 7,
In the step (b), the concentration of each solute in the Al (OH) ₃ solution, the B-containing compound solution or the Si-containing compound solution is 1 to 1000 ppm
(Method for producing positive electrode active material for lithium secondary battery).
8. The method of claim 7,
In the step (c), the weight ratio of the surface treatment solution and the lithium-containing compound is 0.5: 1 to 1: 3
(Method for producing positive electrode active material for lithium secondary battery).
8. The method of claim 7,
In the step (c), mixing and drying are performed simultaneously
(Method for producing positive electrode active material for lithium secondary battery).
delete delete delete A lithium secondary battery comprising the cathode active material according to any one of claims 1 to 3 and 6.

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