JP2009289726A - Lithium transition metal system compound powder, method of manufacturing the same, and spray-dried material to become its calcination precursor, and positive electrode for lithium secondary battery using the same, and lithium secondary cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium transition metal system compound powder for a lithium secondary battery positive electrode material capable of making its cost lower, capacity higher, output higher, life longer and safety higher. <P>SOLUTION: The lithium transition metal system compound powder for a lithium secondary battery positive electrode material contains one or more elements selected from Mo, W, Nb and Re of 0.1 to 5 mol% to a total mol volume of Mn, Ni and Co in a formula (I) [L]<SB>3a</SB>[M]<SB>3b</SB>[O<SB>2</SB>]<SB>6c</SB>, wherein L=Li, M=Ni, Mn and Co, or Li, Ni, Mn and Co. 0.4≤Ni/(Mn+Ni+Co) mol ratio <0.7, 0.1<Mn/(Mn+Ni+Co) mol ratio ≤0.4, 0.1≤Co/(Mn+Ni+Co) mol ratio ≤0.3. A Li mol ratio in M is 0 to 0.05. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lithium transition metal-based compound powder used as a lithium secondary battery positive electrode material, a method for producing the same, a positive electrode for a lithium secondary battery using the lithium transition metal-based compound powder, and the lithium secondary battery The present invention relates to a lithium secondary battery including a positive electrode for a battery.

  Lithium secondary batteries are excellent in energy density and output density, and are effective in reducing the size and weight. Therefore, the demand for power supplies for portable devices such as notebook computers, mobile phones, and handy video cameras is growing rapidly. ing. Lithium secondary batteries are also attracting attention as power sources for electric vehicles and power load leveling, and in recent years, demand for power sources for hybrid electric vehicles is rapidly expanding. In particular, in electric vehicle applications, it is necessary to be excellent in low cost, safety, life (particularly under high temperature) and load characteristics, and improvements in materials are desired.

Among the materials constituting the lithium secondary battery, as the positive electrode active material, a substance having a function capable of desorbing and inserting lithium ions can be used. There are various types of these positive electrode active material materials, each having its own characteristics. In addition, a common problem for improving performance is to improve load characteristics, and improvements in materials are strongly desired.
Furthermore, there is a demand for a material with a good performance balance that is excellent in low cost, safety, and life (particularly under high temperatures).

  Currently, lithium manganese composite oxides having a spinel structure, layered lithium nickel composite oxides, layered lithium cobalt composite oxides, and the like have been put into practical use as positive electrode active material materials for lithium secondary batteries. All of the lithium secondary batteries using these lithium-containing composite oxides have advantages and disadvantages in terms of characteristics. That is, a lithium manganese composite oxide having a spinel structure is inexpensive and relatively easy to synthesize, and is excellent in safety when used as a battery, but has a low capacity and inferior high-temperature characteristics (cycle and storage). Layered lithium-nickel composite oxides have high capacity and excellent high-temperature characteristics, but are difficult to synthesize, have inferior safety when used as batteries, and have drawbacks such as requiring careful storage. Layered lithium cobalt-based composite oxides are widely used as power sources for portable devices because they are easy to synthesize and have an excellent balance of battery performance. However, they are not sufficient in safety and costly. It is a drawback.

  Under these circumstances, lithium nickel manganese cobalt-based composite oxides having a layered structure have been overcome as disadvantages of these positive electrode active material materials as possible candidates for active material materials that can overcome or be reduced as much as possible and are excellent in battery performance balance. Proposed. In particular, in recent years, demands for cost reduction, high capacity, safety, high output, and long life have been increasing, and it is considered promising as a positive electrode active material that can meet these demands.

  In particular, as one of the options for reducing the cost and increasing the capacity, the ratio of expensive cobalt is reduced and the nickel / manganese ratio is set to approximately 1 or less, and a higher charging voltage is set and used. There is a way. However, setting a higher charging voltage has a problem that the load on the electrolytic solution is large, resulting in gas generation and deterioration in storage characteristics. As an alternative, there is a method in which the ratio of expensive cobalt is reduced and the nickel / manganese ratio is set to about 1 or more without using a high charging voltage. However, the lithium nickel manganese cobalt composite oxide having such a composition range is easily sintered at a relatively low firing temperature, and as a result, productivity is lowered or high crystals cannot be obtained. The lithium secondary battery used as the positive electrode material has a relatively low capacity and low output characteristics. Therefore, further improvement was necessary for practical use.

  Therefore, in order to solve the problem of improving the output characteristics while reducing the cost, increasing the capacity, and extending the life, the inventors select a limited composition range and in the stage of firing the selected composition range. In addition to suppressing sintering while maintaining sufficiently high crystallinity, it is important to modify the particle surface so that the resistance at the interface between the active material and the electrolyte is low when it is made into a battery. As a result, in the layered lithium nickel manganese cobalt-based composite oxide of a specific composition region, after adding a compound containing an element such as W, sintering is suppressed by firing at a temperature of a certain level or more, and As a result, it was found that a lithium transition metal compound powder having a surface state in which the interfacial resistance with the electrolytic solution was greatly reduced was obtained, and the present invention was completed. According to the present invention, as a positive electrode material for a lithium secondary battery, it is possible to improve output characteristics in addition to cost reduction, capacity increase, and life extension.

  Therefore, the feature of the present invention is that the layered lithium nickel manganese cobalt-based composite oxide having a specific composition region with a nickel / manganese ratio of 1 or more and a reduced cobalt ratio is selected from Mo, W, Nb, Ta, and Re. And adding a compound containing at least one or more specific elements so as to be highly uniform, followed by firing at a certain temperature or higher.

On the other hand, for the purpose of improving the positive electrode active material, in the lithium nickel manganese cobalt-based composite oxide, as a known document in which the W, Mo, Nb, Ta, and Re-containing compounds disclosed in the present invention are added and treated as follows, Patent Documents 1 to 13 and Non-Patent Documents 1 and 2 are disclosed.
Japanese Patent No. 3088716 Japanese Patent No. 3362025 JP 2002-151071 A WO2002-41419 JP 2003-68298 A JP 2004-303673 A JP 2005-235628 A JP-A-2005-251716 JP 2006-164934 A JP 2006-202647 A JP 2006-202702 A JP 2007-18985 A JP 2007-242581 A Microelectronics Journal, 36 (2005) 491. J. Power Sources, 162 (2006) 1367.

  Patent Documents 1 and 2 disclose that lithium, nickel-based composite oxide having a layered structure uses W, Mo, Ta, and Nb as substitution elements for transition metal sites. It is described that the thermal stability is improved. However, since the composition is mainly composed of Li and Ni, there is still a problem that an active material excellent in various battery characteristic balances cannot be obtained.

  Patent Document 3 discloses the use of lithium nickel manganese cobalt niobium composite oxide. However, the Mn molar ratio in the transition metal site is as low as 0.1 or less, and there is still a problem that an active material excellent in various battery characteristic balances cannot be obtained.

Patent Document 4 discloses that lithium nickel manganese cobalt-based oxides containing W and Mo are used, which makes the thermal stability in a charged state cheaper and higher in capacity than LiCoO _2. It is described that it is excellent. However, in the examples, since the Ni—Mn—Co composite oxide having an average particle diameter of 10 μm, lithium hydroxide and tungsten trioxide or molybdenum trioxide are mixed and fired, the reaction is not uniform. As a result, in addition to the main diffraction peak attributed to the hexagonal crystal structure, a diffraction peak of Li and W composite oxide and / or Li and Mo composite oxide is included, and various battery characteristics balance still remains. There was a problem that an excellent active material could not be obtained.

  Patent Document 5 discloses that in a lithium nickel manganese cobalt-based oxide having a layered structure, Ta, Nb is used as a substitution element for a transition metal site, and thus a usable voltage range is wide, It describes that the charge / discharge cycle durability is good and the capacity is high and the safety is high. However, looking at the examples, Ni-Mn-Co coprecipitated oxide powder having an average particle size of 8 μm, niobium oxide powder, and lithium hydroxide powder are mixed and fired, and therefore the reaction is non-uniform. As a result, there was still a problem that an active material excellent in various battery characteristic balances could not be obtained.

  Patent Document 6 discloses an example in which W is substituted for a transition metal site in a lithium nickel manganese cobalt based composite oxide. However, since the Mn molar ratio in the transition metal site is as extremely small as 0.01 and the Ni molar ratio is as large as 0.8, it is still impossible to obtain an active material excellent in various battery characteristic balances. was there.

  Patent Document 7 discloses that in a monoclinic lithium manganese nickel-based composite oxide, a transition metal site substituted with Nb, Mo, W is used as a positive electrode active material. It is described that a lithium secondary battery with high energy density, high voltage, and high reliability can be provided. However, since Co is not contained as a transition metal element, crystals are not sufficiently developed, and the molar ratio of Nb, Mo, and W is too high as 5 mol%, so that an active material having an excellent balance of various battery characteristics is still obtained. There was a problem that I could not.

  Patent Document 8 discloses that a lithium-transition metal oxide particle having a layered structure has a compound having molybdenum and tungsten on at least the surface thereof, thereby providing excellent battery characteristics even in a more severe use environment. It is described that it has. However, according to the examples, since the Co / (Ni + Co + Mn) molar ratio is too large, 0.33, there is still a problem that an active material excellent in various battery characteristic balances cannot be obtained.

  Patent Document 9 discloses the use of a lithium nickel manganese cobalt molybdenum composite oxide. However, in the examples, LiOH, Mn—Ni—Co coprecipitated hydroxide and molybdenum oxide are mixed and fired in a rough mortar, so that the reaction becomes non-uniform and Co / ( Ni + Mn + Co) has a high Co ratio of 0.34, and there is still a problem that an active material excellent in various battery characteristic balances cannot be obtained.

  Patent Documents 10 and 11 disclose the use of lithium nickel manganese cobalt-based composite oxides containing Nb, Mo, and W. However, looking at the examples, none of the above three elements are used, and since only Mn / Ni molar ratio of 1 has been implemented, it is still possible to obtain an active material excellent in various battery characteristic balances. There was a problem that could not.

  Patent Document 12 discloses that the surface layer of a lithium nickel manganese cobalt composite oxide has W, Nb, Ta, and Mo. However, looking at the manufacturing method of the example, since the above-described element is processed at a relatively low temperature on the positive electrode active material and supported on the surface, only the additive element exists in the surface layer portion of the active material. Therefore, it is expected not to have a continuous composition gradient structure that exists with a non-linear concentration gradient in the depth direction from the primary particle surface. Therefore, there is still a problem that an active material excellent in various battery characteristic balances cannot be obtained.

  Patent Document 13 discloses that a layered lithium nickel manganese composite oxide containing Li in a site containing a transition metal further contains Nb, W, and Mo. However, in addition to not having Co, the examples had a composition with a Ni / Mn molar ratio of 1 or less, and there was still a problem that an active material excellent in various battery characteristic balances could not be obtained.

Non-Patent Document 1 discloses a LiNi _1/3 Mn _1/3 Mo _1/3 O ₂ composite oxide having a layered structure. However, in addition to the Mo content being too high, since Co is not contained, there is still a problem that an active material having an excellent balance of various battery characteristics cannot be obtained.

Non-Patent Document 2 discloses a Mo-doped LiNi _1/3 Mn _1/3 Co _1/3 O ₂ composite oxide. However, in addition to the large Co / (Ni + Mn + Co) molar ratio of 1/3, there is only a composition with a Ni / Mn molar ratio of 1, and for this composition, the maximum firing temperature is as low as 900 ° C. Furthermore, all the other raw materials are acetate (water-soluble) except that oxide (MoO3) is used as the Mo raw material. As can be seen from the SEM image of Non-Patent Document 2, the primary particle size grows to about 2 microns even at a firing temperature as low as 800 ° C. Therefore, there is still a problem that an active material excellent in various battery characteristic balances cannot be obtained.

  That is, the object of the present invention is to improve the output characteristics while increasing the capacity in use as a positive electrode material for a lithium secondary battery, and more preferably to reduce the cost and extend the life. Lithium transition metal compound powder for secondary battery positive electrode material, production method thereof, positive electrode for lithium secondary battery using this lithium transition metal compound powder, and lithium equipped with this positive electrode for lithium secondary battery It is to provide a secondary battery.

  In order to solve the problem of improving the output characteristics while increasing the capacity, the present inventors have made layered lithium nickel manganese having a specific composition region in which the nickel / manganese ratio is 1 or more and the cobalt ratio is reduced. In a cobalt-based composite oxide, a compound containing a specific element such as W is added so as to be highly uniform, and then fired at a temperature of a certain level or more, so that it has an excellent capacity as a positive electrode material for a lithium secondary battery. The inventors have found that lithium transition metal-based compound powders exhibiting characteristics, high output characteristics and long life characteristics and capable of reducing costs can be obtained, and the present invention has been completed.

That is, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a composition represented by the following formula (I) and at least one selected from Mo, W, Nb, Ta and Re. Is contained in a proportion of 0.1 mol% or more and 5 mol% or less with respect to the total molar amount of Mn, Ni and Co in the formula (I) (Claim 1). .
[L] _3a [M] _3b [O ₂ ] _6c (I)
(However, in the above formula (I), L is an element containing at least Li, and M is an element containing at least Ni, Mn and Co, or Li, Ni, Mn and Co,
0.4 ≦ Ni / (Mn + Ni + Co) molar ratio <0.7
0.1 <Mn / (Mn + Ni + Co) molar ratio ≦ 0.4
0.1 ≦ Co / (Mn + Ni + Co) molar ratio ≦ 0.3
And the molar ratio of Li in M is 0 or more and 0.05 or less.
The subscript next to [] represents a site in the crystal structure, the 3a site being the Li site, the 3b site being the transition metal site, and the 6c site being the oxygen site. )

In the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, M in the formula (I) is preferably represented by the following formula (II) (claim 2).
M = Li _{z / (2 + z)} (Ni _1-xy Mn _x Co _y ) _{2 / (2 + z)} (II)
(However, in the above formula (II),
0.1 <x ≦ 0.4
0.15 ≦ y ≦ 0.25
0.001 ≦ z ≦ 0.1
It is. )

  In addition, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention has a diffraction angle 2θ of around 64.5 to 65 ° in powder X-ray diffraction measurement using CuKα rays (110). When the half width derived from the CuKα1 line of the diffraction peak is FWHM (110), it is preferably represented by 0.01 ≦ FWHM (110) ≦ 0.3 (Claim 3).

In addition, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention has a diffraction angle 2θ of around 64 to 64.5 ° in powder X-ray diffraction measurement using CuKα rays (018). In the diffraction peak, the (110) diffraction peak existing in the vicinity of 64.5 to 65 °, and the (113) diffraction peak existing in the vicinity of 68 to 68.5 °, derived from a different phase at a higher angle side than the respective peak tops. When it has no diffraction peak or has a diffraction peak derived from a different phase, it is preferable that the integrated intensity ratio of the different phase peak to the diffraction peak of the original crystal phase is in the following range, respectively.
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.10
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.15
0 ≦ I ₁₁₃ ^* / I ₁₁₃ ≦ 0.30
(Here, I ₀₁₈ , I ₁₁₀ , and I ₁₁₃ represent the integrated intensities of the diffraction peaks, respectively (018), (110), and (113), and I ₀₁₈ ^* , I ₁₁₀ ^* , and I ₁₁₃ ^* are (018 ), (110), (113) represents the integrated intensity of a diffraction peak derived from a different phase appearing at a higher angle than the peak top of the diffraction peak.)

  Further, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention is such that primary particles of the lithium transition metal compound powder aggregate to form secondary particles, and the median diameter of the secondary particles The ratio A / B between A and the average diameter (average primary particle diameter B) is preferably in the range of 8 to 100 (Claim 5).

  In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention is composed of Mo, W, Nb with respect to the total of Li and Mo, W, Nb, Ta and Re in the surface part of the primary particles. The total atomic ratio of Ta, Re is preferably 5 times or more the atomic ratio of the entire primary particle (claim 6).

The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention is composed of Mo, W, Nb, and Li on the outermost surface of the primary particles with respect to the total of metal elements other than Mo, W, Nb, Ta, and Re. ratio of Ta and total atomic ratio _{R 0} of Re, a total atomic ratio _{R 10} of the metal element to the sum of Li and a metal element other than the metal element in the depth 10nm from the surface of the primary particles _R 0 _{/ R 10} Is preferably 3 times or more (claim 7).

  In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention contains at least one element selected from Mo, W, Nb, Ta and Re in the depth direction from the surface of the primary particles. It is preferable to have a continuous composition gradient structure that exists with a linear concentration gradient (claim 8).

  Moreover, in the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention, in the formula (I), the mixing ratio of metal elements other than Li to the 3a site is preferably 6% or less ( Claim 9).

Further, the lithium secondary battery positive electrode material for a lithium transition metal based compound powder according to the present invention, in the infrared absorption spectrum, a peak appeared in the vicinity 560～610Cm ^-1, the peak appeared in the vicinity 515～540Cm ^-1 It is preferable to have a bonded structure in which the difference is 40 cm ⁻¹ or more and 80 cm ⁻¹ or less (claim 10).

Further, the lithium secondary battery positive electrode material for a lithium transition metal based compound powder according to the present invention, a surface enhanced Raman spectrum, 530 cm ^-1 or more, and preferably has a peak A to 630 cm ^-1 or less (claim 11) .

The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a volume resistivity of 1 × 10 ¹ Ω · cm or more and 5 × 10 ⁶ Ω · cm or less when consolidated at a pressure of 40 MPa. (Claim 12).

  In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a C value of 0.005% or more and 0.25% by weight or less when the carbon concentration is C value (% by weight). (Claim 13).

  Further, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention is set to a refractive index of 1.24 by a laser diffraction / scattering type particle size distribution measuring device, and a particle diameter reference is a volume reference. The median diameter measured after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz) is preferably 1 μm or more and 20 μm or less (claim 14).

  In the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention, the average primary particle diameter is preferably 0.1 μm or more and 1 μm or less (claim 15).

The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention preferably has a BET specific surface area of 0.5 m ² / g or more and 3 m ² / g (Claim 16).

The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a mercury intrusion amount of 0.4 cm ³ in a mercury intrusion curve by a mercury intrusion method at a pressure of 3.86 kPa to 413 MPa. / G or more and 1.2 cm ³ / g or less (claim 17).

  In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has at least one main peak having a peak top at a pore radius of 400 nm or more and 1500 nm or less as measured by a mercury intrusion method. And a sub-peak having a peak top at a pore radius of 80 nm or more and less than 400 nm (claim 18).

In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a fine peak related to a main peak having a peak top at a pore radius of 400 nm or more and 1500 nm or less in a pore distribution curve by a mercury intrusion method. The pore volume of the sub-peak in which the pore volume is 0.2 cm ³ / g or more and 0.8 cm ³ / g or less and the peak top exists at a pore radius of 80 nm or more and less than 400 nm is 0.01 cm ³ / g. As mentioned above, it is preferable that it is 0.2 cm < ³ > / g or less (Claim 19).

In addition, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention preferably has a bulk density of 1.0 g / cm ³ or more and 2.5 g / cm ³ or less (claim 20).

  Moreover, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention uses lithium carbonate as a lithium raw material, and in an oxygen-containing gas atmosphere, a firing temperature of 1150-500 (1-xy). (However, x and y are synonymous with x and y in the formula (II), and represent 0.1 ≦ x ≦ 0.4 and 0.15 ≦ y ≦ 0.25.) It is preferable that it is made (claim 21).

  The method for producing a lithium transition metal compound powder for a positive electrode material of a lithium secondary battery according to the present invention is at least one selected from lithium carbonate, Ni compound, Mn compound, Co compound, and Mo, W, Nb, Ta, and Re. A spray drying step of spraying a slurry obtained by pulverizing a metal compound containing more than one element in a liquid medium and uniformly dispersing them, and a firing step of firing the obtained spray-dried body (Claim 22).

  The method for producing a lithium transition metal compound powder for a lithium secondary battery positive electrode material according to the present invention has a refractive index of 1. in a slurry adjustment step using a laser diffraction / scattering particle size distribution measuring device in a liquid medium. In the spray drying process, the particle size reference is set to 24, and the particle size reference is volume reference, and the mixture is pulverized until the median diameter measured after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz) is 0.5 μm or less. When the slurry viscosity during drying is V (cp), the slurry supply amount is S (L / min), and the gas supply amount is G (L / min), 50 cp ≦ V ≦ 4000 cp, 500 ≦ G / S ≦ 10000 It is preferable to perform spray drying under the following conditions (claim 23).

The spray-dried product of the present invention comprises lithium carbonate, a Ni compound, a Mn compound, a Co compound, and a metal compound containing at least one element selected from Mo, W, Nb, Ta, and Re in a liquid medium. A spray-dried product that is obtained by spray-drying a slurry in which these are uniformly dispersed and spray-dried, and is a precursor of a lithium transition metal compound powder for a positive electrode material for a lithium secondary battery, and is laser diffraction / scattering Ultrasonic dispersion for 5 minutes with respect to the median diameter D ₅₀ [US0] measured without applying ultrasonic dispersion, with the refractive index set to 1.24 by the particle size distribution measuring apparatus using the particle diameter standard as the volume standard ( that the output 30 W, frequency 22.5 kHz) measured ratio of median diameter _D 50 [US5] _{after, D 50 [US5] / D} 50 [US0] 0.03 or more and 0.7 or less Wherein (claim 24).

The spray-dried body of the present invention preferably has a BET specific surface area of 10 m ² / g or more and 100 m ² / g or less (claim 25).

  The positive electrode for a lithium secondary battery of the present invention has, on a current collector, a positive electrode active material layer containing the above-described lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention and a binder. (Claim 26).

  The lithium secondary battery of the present invention is a lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a non-aqueous electrolyte containing a lithium salt, and a positive electrode capable of inserting and extracting lithium. Such a positive electrode for a lithium secondary battery according to the present invention is used (claim 27).

  The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, when used as a lithium secondary battery positive electrode material, achieves both low cost and high safety, high load characteristics, and improved powder handleability. Can be achieved. For this reason, according to the present invention, a lithium secondary battery that is inexpensive, excellent in handleability, high in safety, and excellent in performance is provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents.

[Lithium transition metal compound powder]
The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention will be described below.

  The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention (hereinafter sometimes referred to as “positive electrode active material”) has a composition represented by the following formula (I), and Mo, W, At least one element selected from Nb, Ta and Ze is contained in a proportion of 0.1 mol% or more and 5 mol% or less with respect to the total molar amount of Mn, Ni and Co in formula (I). It is characterized by.

[L] _3a [M] _3b [O ₂ ] _6c (I)
(However, in the above formula (I), L is an element containing at least Li, and M is an element containing at least Ni, Mn and Co, or Li, Ni, Mn and Co,
0.4 ≦ Ni / (Mn + Ni + Co) molar ratio <0.7
0.1 <Mn / (Mn + Ni + Co) molar ratio ≦ 0.4
0.1 ≦ Co / (Mn + Ni + Co) molar ratio ≦ 0.3
And the molar ratio of Li in M is 0 or more and 0.05 or less.
The subscript next to [] represents a site in the crystal structure, the 3a site being the Li site, the 3b site being the transition metal site, and the 6c site being the oxygen site. )

<Composition>
The lithium-containing transition metal compound powder of the present invention is a lithium transition metal-based composite oxide powder represented by the formula (I).
L is an element containing at least Li. Examples of elements other than Li include metal elements such as Ni, Mn, and Co.
M is an element composed of at least Ni, Mn, and Co, or Li, Ni, Mn, and Co, and the Ni / (Mn + Ni + Co) molar ratio is 0.4 or more, preferably 0.42 or more, more preferably 0.45 or more, most preferably 0.48 or more, usually less than 0.7, preferably 0.68 or less, more preferably 0.65 or less, and most preferably 0.62 or less.

  Mn / (Mn + Ni + Co) molar ratio is greater than 0.1, preferably 0.12 or more, more preferably 0.15 or more, most preferably 0.18 or more, usually 0.4 or less, preferably 0.38 or less, More preferably, it is 0.35 or less, and most preferably 0.32 or less.

  Co / (Mn + Ni + Co) molar ratio is 0.1 or more, preferably 0.12 or more, more preferably 0.15 or more, most preferably 0.18 or more, usually 0.3 or less, preferably 0.30, and more preferably Is 0.28 or less, more preferably 0.25 or less, and most preferably 0.22 or less.

  The Li molar ratio in M is 0 or more, preferably 0.001 or more, more preferably 0.005 or more, still more preferably 0.01 or more, most preferably 0.02 or more, usually 0.05 or less, preferably 0. 0.045 or less, more preferably 0.04 or less, further preferably 0.035 or less, and most preferably 0.03 or less.

  If the composition is out of the above range, the intended effect of the present invention may not be easily obtained.

  In the above formula (I), the atomic ratio of the oxygen amount is described as 2 for convenience, but there may be some non-stoichiometry. In the case of non-stoichiometry, the atomic ratio of oxygen is usually in the range of 2 ± 0.2, preferably in the range of 2 ± 0.15, more preferably in the range of 2 ± 0.12, and even more preferably 2 ± 0.10. And particularly preferably in the range of 2 ± 0.05.

  Further, the lithium transition metal-based compound powder of the present invention contains at least one element selected from Mo, W, Nb, Ta and Re, but other foreign elements may be introduced. Other different elements include B, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Sr, Y, Zr, Ru, Rh, Pd, Ag In, Sn, Sb, Te, Ba, Os, Ir, Pt, Au, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu , N, F, P, S, Cl, Br, or I. These foreign elements may be incorporated into the crystal structure of the lithium nickel manganese cobalt composite oxide, or may not be incorporated into the crystal structure of the lithium nickel manganese cobalt composite oxide. It may be unevenly distributed as a single substance or a compound in the boundary. In the present invention, the element containing Mo, W, Nb, Ta, and Re may be referred to as “additive element” or “additive”.

<Preferred composition>
The lithium transition metal-based composite oxide powder for a lithium secondary battery positive electrode material of the present invention is particularly preferably one in which the atomic configuration in the M site in the formula (I) is represented by the following formula (II).

M = Li _{z / (2 + z)} (Ni _1-xy Mn _x Co _y ) _{2 / (2 + z)} (II)
(However, in the above formula (II),
0.1 <x ≦ 0.4
0.15 ≦ y ≦ 0.25
0.001 ≦ z ≦ 0.1
It is. )

  In the above formula (II), the value of x is usually larger than 0.1, preferably 0.15 or more, more preferably 0.2 or more, still more preferably 0.25 or more, most preferably 0.28 or more. In general, it is 0.4 or less, preferably 0.38 or less, more preferably 0.36 or less, still more preferably 0.34 or less, and most preferably 0.32 or less.

  The value of y is usually 0.15 or more, preferably 0.16 or more, most preferably 0.18 or more, usually 0.25 or less, preferably 0.24 or less, more preferably 0.23 or less, most preferably 0. .22 or less.

  The value of z is usually 0.001 or more, preferably 0.01 or more, more preferably 0.02 or more, further preferably 0.03 or more, most preferably 0.04 or more, usually 0.1 or less, preferably 0. 0.09 or less, more preferably 0.08 or less, and most preferably 0.075 or less. If the lower limit is not reached, the conductivity decreases, and if the upper limit is exceeded, the amount of substitution to the transition metal site becomes too large and the battery capacity becomes low. is there. On the other hand, when z is too large, the carbon dioxide absorbability of the active material powder increases, and it becomes easy to absorb carbon dioxide in the atmosphere. As a result, it is estimated that the concentration of contained carbon increases.

  In the composition range of the above formula (II), as the z value is closer to the lower limit of the constant ratio, the battery tends to have lower rate characteristics and output characteristics, while the z value is closer to the upper limit. Although the rate characteristics and output characteristics of the battery are improved, there is a tendency for the capacity to decrease. In addition, the closer the x value is to the lower limit, the higher the capacity is developed, but the chemical stability and safety tend to decrease. Conversely, the closer the x value is to the upper limit, the more chemical stability and safety are exhibited. While improving, the capacity tends to decrease. In addition, as the y value is closer to the lower limit, there is a tendency that the rate characteristic and the output characteristic are lowered. Conversely, as the y value is closer to the upper limit, the rate characteristic and the output characteristic are increased, but when this upper limit is exceeded, Cycle characteristics and safety are reduced, and raw material costs are increased. Setting the composition parameters x, y, and z within a specified range is an important component of the present invention.

Here, the chemical meaning of excess Li (z) in the preferred composition of the lithium transition metal-based compound powder of the present invention will be described in more detail below.
As described above, the layered structure is not necessarily limited to the layered R (-3) m structure, but it is preferable from the viewpoint of electrochemical performance that it can belong to the layered R (-3) m structure.
In order to obtain x, y, and z in the composition formula of the lithium transition metal compound, each transition metal and Li are analyzed by an inductively coupled plasma emission spectrometer (ICX-AES), and Li / Ni / Mn / Co It is calculated by calculating the ratio of.

From a structural point of view, Li related to z is considered to be substituted with the same transition metal site (3b). Here, the Li related to z increases the average valence of Ni based on the principle of charge neutrality (trivalent Ni is generated). That is, z increases the Ni average valence, and thus becomes an index of the Ni valence (the ratio of Ni (III)).

  From the above composition formula, when calculating the Ni valence (m) accompanying the change of z, the Co valence is trivalent and the Mn valence is tetravalent,

It becomes. This calculation result means that the Ni valence is not determined only by z but is a function of x and y. When x = z, that is, when the amount of Mn is equal to the amount of excess Li, it is suggested that the Ni valence becomes trivalent regardless of the y value (Co amount). When the z value (excess Li amount) is 0 and x (Mn amount) = 1−xy (Ni amount), the Ni valence is divalent. This means that even if the z value is the same, the Ni valence becomes higher as the composition is richer in Ni (1-xy value is larger) and / or Mn poor (smaller in x value), and used in the battery. In this case, the rate characteristic and the output characteristic are improved, but on the other hand, the capacity tends to decrease.

  Moreover, if the y value is 0.15 ≦ y ≦ 0.25 and the amount of Co is in an appropriate range, the charge / discharge capacity and rate characteristics are improved, and the battery has an excellent battery performance balance. Is preferable.

  In the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention, the source containing a specific amount of any one or more of Mo, W, Nb, Ta, and Re contains the element. This is by intentionally adding the compound to be added. After adding the compound containing the element to the firing precursor of the lithium transition metal compound for lithium secondary battery positive electrode material so as to be fine and uniform, heat treatment is performed at a high temperature, so that grain growth during firing By having a continuous composition gradient structure that exerts the effect of suppressing sintering and is concentrated on the active material particle surface and distributed with a non-linear concentration gradient from the particle surface in the depth direction, the output characteristics are improved. It has been found that it also has the effect of greatly improving.

The compound containing the element used for the addition is not particularly limited in type, but an oxide is usually used. Is exemplified _{compounds, MoO, MoO 2, MoO 3} , MoO x, Mo 2 O 3, Mo 2 O 5, Li 2 MoO 4, WO, WO 2, WO 3, WO x, W 2 O 3, W 2 O ₅ , W ₁₈ O ₄₉ , W ₂₀ O ₅₈ , W ₂₄ O ₇₀ , W ₂₅ O ₇₃ , W ₄₀ O ₁₁₈ , Li ₂ WO ₄ , NbO, NbO ₂ , Nb ₂ O, Nb ₂ O ₅ , Nb ₄ O , Nb ₆ O, LiNbO ₃ , TaO, TaO ₂ , Ta ₂ O ₅ , LiTaO ₃ , ReO ₂ , ReO ₃ , Re ₂ O _{3 and the} like, preferably MoO ₃ , Li ₂ MoO ₄ , WO ₃ , Li ₂ WO ₄ , LiNbO ₃ , Ta ₂ O ₅ , LiTaO ₃ and ReO ₃ are mentioned, and particularly preferred are WO ₃ , Li ₂ WO ₄ , Ta ₂ O ₅ and ReO ₃ .

  The total content of the elements in the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention is usually 0.1 mol% or more with respect to the total molar amount of (Mn, Ni, Co). , Preferably 0.2 mol% or more, more preferably 0.4 mol% or more, further preferably 0.6 mol% or more, most preferably 0.8 mol% or more, and usually 5 mol% or less, preferably Is 4 mol% or less, more preferably 3 mol% or less, still more preferably 2 mol% or less, and most preferably 1.5 mol% or less. If the lower limit is not reached, the above effects may not be obtained. If the upper limit is exceeded, battery performance may be reduced.

  The lithium transition metal-based compound powder of the present invention is characterized in that at least one element selected from Mo, W, Nb, Ta and Re is present on the surface of the primary particles in a concentrated manner. is there. Specifically, the molar ratio of the total of the elements to the total of Li on the surface portion of the primary particles and the metal elements other than the elements (that is, Li and the metal elements other than the elements) is usually that of the entire particle. More than 5 times the atomic ratio. The lower limit of this ratio is preferably 6 times or more, more preferably 7 times or more, and particularly preferably 8 times or more. The upper limit is not particularly limited, but is preferably 100 times or less, more preferably 50 times or less, particularly preferably 30 times or less, and most preferably 20 times or less. If this ratio is too small, the effect of improving battery performance is small, while if too large, battery performance may be deteriorated.

  Analysis of the composition of the surface part of the primary particles of the lithium transition metal compound powder was performed by X-ray photoelectron spectroscopy (XPS), using monochromatic light AlKα as an X-ray source, an analysis area of 0.8 mm diameter, and an extraction angle of 65 °. Perform under the conditions of Although the range (depth) that can be analyzed varies depending on the composition of the primary particles, it is usually 0.1 nm to 50 nm, particularly 1 nm to 10 nm for a positive electrode active material. Therefore, in the present invention, the surface portion of the primary particles of the lithium transition metal-based compound powder indicates a measurable range under these conditions.

The composition of the lithium transition metal-based compound powder in the depth direction from the particle surface can be analyzed by alternately performing Ar ion gun sputtering and the same XPS measurement as described above. Since atoms near the surface are removed by sputtering, the subsequent XPS measurement reflects the composition inside the particles before sputtering. Here, since it is difficult to accurately know the thickness of the surface layer removed by sputtering, the thickness of the SiO ₂ surface layer removed by performing sputtering of the SiO ₂ thin film under the same conditions is substituted. Therefore, in the present invention, the depth from the particle surface of the lithium transition metal compound indicates the depth estimated by this method.

The total of the elements with respect to the total of Li and metal elements other than the above elements (that is, metal elements other than Li and Mo, W, Nb, Ta, and Re) on the outermost surface of the particles of the lithium transition metal compound powder of the present invention The ratio R ₀ / R ₁₀ between the atomic ratio R ₀ and the atomic ratio R ₁₀ at a depth of 10 nm from the particle surface is usually 3 times or more, preferably 3.2 times or more, and usually 10 times or less, preferably 8 It is not more than twice, more preferably not more than 7 times, still more preferably not more than 6 times, and most preferably not more than 5 times.

<Presence form of additive element>
The lithium transition metal-based compound powder of the present invention preferably has a continuous composition gradient structure in which the additive element exists with a concentration gradient in the depth direction from the particle surface.

  The lithium transition metal-based composite oxide powder for a lithium secondary battery positive electrode material of the present invention has a mixing ratio of metal elements other than Li to the 3a site obtained from the Rietveld analysis of precision X-ray diffraction is 6% or less. Is preferably 5.5% or less, more preferably 5% or less. When deviating from the above range, the effects of the present invention may not be sufficiently obtained.

  In addition, the lithium transition metal-based composite oxide powder for a lithium secondary battery positive electrode material of the present invention is centered on (Ni, Mn, Co) atoms from atomic position coordinates obtained from Rietveld analysis of precision X-ray diffraction. The oxygen octahedron distortion (ODP = Octahedral Displacement Parameter) ODP = do-o, intra / do-o, inter where do-o, intra is the distance between oxygen atoms in the plane formed by the a-axis and b-axis , Do-o, inter are preferably those in which the lower limit of the ODP value is 1.050 or more when the out-of-plane oxygen interatomic distance across the (Ni, Mn, Co) atomic layer is determined. What becomes above is more preferable, and what becomes 1.057 or more is especially preferable. The upper limit is preferably 1.075 or less, more preferably 1.070 or less, and particularly preferably 1.065 or less. When deviating from the above range, the effects of the present invention may not be sufficiently obtained.

In the lithium transition metal-based composite oxide powder for a lithium secondary battery positive electrode material of the present invention, a peak A appears in the vicinity of 560 to 610 cm ⁻¹ in an infrared absorption spectrum (FT-IR) measurement, and 515 to 540 cm ^−1. It is preferable that the peak B appears in the vicinity, and the difference Δ between the peak A and the peak B is 40 cm ⁻¹ or more and 80 cm ⁻¹ or less. The lower limit of the difference Δ value is more preferably 45 cm ⁻¹ or more, further preferably 50 cm ⁻¹ or more, and most preferably 55 cm ⁻¹ or more. The upper limit is more preferably 75 cm ⁻¹ or less, still more preferably 70 cm ⁻¹ or less, and most preferably 65 cm ⁻¹ or less. If the Δ value deviates from the specified value, the effects of the present invention may not be sufficiently obtained.

In the present invention, the surface-enhanced Raman spectrum has a peak A at 530 cm ⁻¹ or more and 630 cm ⁻¹ or less. Position of the peak A is usually 530 cm ^-1 or more, preferably 540 cm ^-1 or more, more preferably 550 cm ^-1 or more, more preferably 560 cm ^-1 or more, and most preferably at 570 cm ^-1 or more and usually 630 cm ^-1 or less , preferably 600 cm ^-1 or less, more preferably 590 cm ^-1 or less, and most preferably 580 cm ^-1 or less. If it deviates from this range, the effects of the present invention may not be sufficiently obtained.

  Here, surface-enhanced Raman spectroscopy (hereinafter abbreviated as SERS) selectively amplifies the Raman spectrum derived from molecular vibrations on the outermost surface of the sample by depositing a noble metal such as silver on the surface of the sample in a very thin sea-island shape. It is a method to do. The detection depth in ordinary Raman spectroscopy is approximately 0.1 to 1 μm, but in SERS, the signal of the surface layer portion in contact with the noble metal particles occupies most of the signal.

In the present invention, the SERS spectrum, 800 cm ^-1 or more, and preferably one having a peak B to 900 cm ^-1 or less. Position of the peak B is usually 800 cm ^-1 or more, preferably 810 cm ^-1 or more, more preferably 820 cm ^-1 or more, more preferably 825cm ^-1 or more, and most preferably at 830 cm ^-1 or more and usually 900 cm ^-1 or less , preferably 860 cm ^-1 or less, more preferably 850 cm ^-1 or less, and most preferably 840 cm ^-1 or less. If it deviates from this range, the effects of the present invention may not be sufficiently obtained.

Furthermore, as described above, the positive electrode active material of the present invention preferably has a peak A intensity greater than 0.04 with respect to the peak B intensity of 600 ± 50 cm ^{−1 in} SERS, and is 0.05 or more. More preferably. Here, the peak B of 600 ± 50 cm ^{−1 is} a peak derived from stretching vibration of M′O ₆ (M ′ is a metal element in the positive electrode active material). When the intensity of peak A relative to peak B is small, the effects of the present invention may not be sufficiently obtained.

<Volume resistivity>
The volume resistivity value when the lithium transition metal-based compound powder of the present invention is compacted at a pressure of 40 MPa is preferably 1 × 10 ¹ Ω · cm or more as a lower limit, and more preferably 5 × 10 ¹ Ω · cm or more. More preferably, 1 × 10 ² Ω · cm or more is more preferable, and 5 × 10 ² Ω · cm or more is most preferable. The upper limit is preferably 5 × 10 ⁶ Ω · cm or less, more preferably 1 × 10 ⁶ Ω · cm or less, further preferably 8 × 10 ⁵ Ω · cm or less, and most preferably 5 × 10 ⁵ Ω · cm or less. . If this volume resistivity exceeds this upper limit, the load characteristics when used as a battery may be reduced. On the other hand, if the volume resistivity is below this lower limit, the safety of the battery may be reduced.

  In the present invention, the volume resistivity of the lithium transition metal based compound powder is such that the four probe / ring electrode, the electrode spacing is 5.0 mm, the electrode radius is 1.0 mm, the sample radius is 12.5 mm, and the applied voltage limiter is 90 V. The volume resistivity measured in a state where the lithium transition metal-based compound powder is compacted at a pressure of 40 MPa. The volume resistivity can be measured, for example, by using a powder resistance measuring device (for example, Lorester GP powder resistance measuring system manufactured by Dia Instruments Co., Ltd.) with a powder probe unit on a powder under a predetermined pressure. It can be carried out.

<Contained carbon concentration C>
The carbon concentration C (wt%) value of the lithium transition metal compound powder of the present invention is usually 0.005 wt% or more, preferably 0.01 wt% or more, more preferably 0.03 wt% or more, most Preferably it is 0.06% by weight or more, usually 0.25% by weight or less, preferably 0.2% by weight or less, more preferably 0.18% by weight or less, still more preferably 0.15% by weight or less, most preferably Is 0.12% by weight or less. If the lower limit is not reached, battery performance may be reduced. If the upper limit is exceeded, swelling due to gas generation when the battery is produced may increase or battery performance may be reduced.

In the present invention, the carbon concentration C of the lithium nickel manganese cobalt-based composite oxide powder is determined by measurement using an oxygen gas combustion (high-frequency heating furnace type) infrared absorption method, as shown in the Examples section below. It is done.
In addition, the carbon component contained in the lithium nickel manganese cobalt composite oxide powder obtained by carbon analysis described later can be regarded as indicating information on the amount of carbonic acid compound, particularly lithium carbonate. This is due to the fact that the carbon amount determined by carbon analysis is assumed to be all derived from carbonate ions, and the carbonate ion concentration analyzed by ion chromatography generally agrees.

  On the other hand, when a composite treatment with conductive carbon is performed as a method for increasing the electron conductivity, a C amount exceeding the specified range may be detected, but such a treatment was performed. The C value in the case is not limited to the specified range.

<Secondary particle shape>
The lithium transition metal-based compound powder of the present invention is preferably formed by agglomerating primary particle crystals to form spherical secondary particles, and in particular, primary particle crystals are randomly aggregated to form spherical secondary particles. What formed the particle | grains is preferable. Whether or not the primary particle crystals are randomly aggregated can be observed in the cross-sectional SEM. Such a form indicates that the secondary particles have substantially no crystal anisotropy. As a result, in the secondary particles, the expansion and contraction of the crystal accompanying the occlusion / release of lithium ions is relieved, the battery characteristics are excellent in cycle reversibility, and in combination with the effect of the substance provision of the first invention, In addition to further higher density, the battery characteristics are improved in a balanced manner.
In the present invention, “spherical” means secondary particles formed by agglomeration of primary particle crystals as shown in the SEM photograph of the lithium nickel manganese cobalt composite oxide powder obtained in Examples described later. The average value of the ratio [Lb / La] of the small diameter [Lb (μm)] at the midpoint in the direction perpendicular to the maximum diameter direction with respect to the maximum diameter [La (μm)] is 0.8 or more. Sure.

<Average primary particle size B>
The average primary particle diameter (average primary particle diameter B) of the lithium transition metal compound powder of the present invention is not particularly limited, but the lower limit is preferably 0.1 μm or more, more preferably 0.2 μm or more, and further Preferably it is 0.3 μm or more, most preferably 0.4 μm or more, and the upper limit is preferably 1 μm or less, more preferably 0.9 μm or less, further preferably 0.7 μm or less, and most preferably 0.5 μm or less. is there. If the average primary particle size exceeds the above upper limit, it may adversely affect the powder filling property or the specific surface area will decrease, which may increase the possibility that the battery performance such as rate characteristics and output characteristics will decrease. There is sex. If the lower limit is not reached, there is a possibility that problems such as inferior reversibility of charge / discharge due to the undeveloped crystals.

  In addition, the average primary particle diameter in this invention is an average diameter observed with the scanning electron microscope (SEM), and is either 3,000 times, 10,000 times, or 30,000 times according to the size of particle | grains. Can be obtained as an average value of the particle diameter of about 10 to 30 primary particles.

<Ratio A / B of median diameter A and average primary particle diameter B of secondary particles>
The ratio A / B between the median diameter A and the average primary particle diameter B of the secondary particles of the lithium transition metal-based compound powder of the present invention represents the tendency of the secondary particle size and the primary particle size of the positive electrode active material powder, The ratio A / B of 8 to 100 means that the powder characteristics such as bulk density and the battery characteristics such as rate are in good balance. If this ratio A / B is less than the above lower limit, it becomes difficult to form spherical secondary particles, so the powder filling property tends to be lowered, and if it exceeds the upper limit, the filling property of the primary particles forming the secondary particles becomes too high. The battery characteristics tend to deteriorate. For this reason, A / B is 8 or more, preferably 9 or more, more preferably 10 or more, and is 100 or less, preferably 80 or less, more preferably 50 or less.

<Median diameter A and 90% integrated diameter ( _D90 )>
The median diameter (median diameter A of the secondary particles) of the lithium transition metal compound powder of the present invention is usually 1 μm or more, preferably 1.5 μm or more, more preferably 2 μm or more, still more preferably 2.5 μm or more, most It is preferably 3 μm or more, usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, still more preferably 9 μm or less, and most preferably 8 μm or less. If the lower limit is not reached, there may be a problem in applicability at the time of forming the positive electrode active material layer, and if the upper limit is exceeded, battery performance may be lowered.

In addition, the 90% cumulative diameter (D ₉₀ ) of the secondary particles of the lithium lithium transition metal compound powder of the present invention is usually 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less, and most preferably 15 μm or less. It is 2 μm or more, preferably 3 μm or more, more preferably 4 μm or more, and most preferably 4.5 μm or more. If the upper limit is exceeded, battery performance may be reduced, and if the lower limit is not reached, there may be a problem in applicability when forming the positive electrode active material layer.

In the present invention, the median diameter and the 90% integrated diameter (D ₉₀ ) as the average particle diameter are set to a refractive index of 1.24 using a known laser diffraction / scattering particle size distribution measuring device, and the particle diameter standard is determined. Measured as a volume reference. In the present invention, a 0.1 wt% sodium hexametaphosphate aqueous solution was used as a dispersion medium used in the measurement, and measurement was performed after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz).

<BET specific surface area>
The lithium-lithium transition metal compound powder of the present invention also has a BET specific surface area of usually 0.5 m ² / g or more, preferably 0.8 m ² / g or more, more preferably 1.0 m ² / g or more, most Preferably it is 1.5 m ² / g or more, usually 3 m ² / g or less, preferably 2.8 m ² / g or less, more preferably 2.5 m ² / g or less, most preferably 2.0 m ² / g or less. is there. If the BET specific surface area is smaller than this range, the battery performance is likely to be lowered, and if it is larger, the bulk density is difficult to increase, and there is a possibility that a problem is likely to occur in the coating property at the time of forming the positive electrode active material.

  The BET specific surface area can be measured by a known BET type powder specific surface area measuring device. In the present invention, an OMS Riken: AMS8000 type automatic powder specific surface area measuring device was used, nitrogen was used as an adsorption gas, and helium was used as a carrier gas. Specifically, the powder sample was heated and deaerated with a mixed gas at a temperature of 150 ° C., then cooled to liquid nitrogen temperature to adsorb the mixed gas, and then heated to room temperature with water to be adsorbed. Nitrogen gas was desorbed, the amount was detected by a heat conduction detector, and the specific surface area of the sample was calculated therefrom.

<Mercury intrusion method>
The lithium-lithium transition metal-based compound powder of the present invention is characterized by satisfying specific conditions in measurement by mercury porosimetry. Therefore, before describing the particles of the present invention, the mercury intrusion method will be briefly described first.
The mercury intrusion method is a method for obtaining information such as specific surface area and pore size distribution from the relationship between pressure and the amount of mercury intruded into a pore of a sample such as porous particles while applying pressure. It is.

  Specifically, first, the container containing the sample is evacuated and filled with mercury. Mercury has a high surface tension, and as it is, mercury does not penetrate into the pores on the sample surface, but when pressure is applied to the mercury and the pressure is gradually increased, the pores increase in size from the smallest to the smallest. Gradually mercury enters the pores. If a change in the mercury liquid level (that is, the amount of mercury intruded into the pores) is detected while the pressure is continuously increased, a mercury intrusion curve representing the relationship between the pressure applied to the mercury and the amount of mercury intruded can be obtained. .

Here, assuming that the pore shape is cylindrical, the radius is r, the surface tension of mercury is δ, and the contact angle is θ, the size in the direction of pushing mercury out of the pore is −2πrδ (cos θ). (If θ> 90 °, this value is positive). Moreover, since the magnitude of the force in the direction of pushing mercury into the pores under the pressure P is represented by πr ² P, the following formulas (1) and (2) are derived from the balance of these forces. It will be.

-2πrδ (cosθ) = πr ² P (1)
Pr = −2δ (cos θ) (2)

  In the case of mercury, values of surface tension δ = 480 dyn / cm and contact angle θ = 140 ° are generally used. When these values are used, the radius of the pore into which mercury is injected under the pressure P is expressed by the following formula (3).

  That is, since there is a correlation between the pressure P applied to mercury and the radius r of the pore into which mercury enters, the size of the pore radius of the sample and its volume are calculated based on the obtained mercury intrusion curve. A pore distribution curve representing the relationship can be obtained. For example, when the pressure P is changed from 0.1 MPa to 100 MPa, the pores in the range from about 7500 nm to about 7.5 nm can be measured.

Note that the approximate measurement limit of the pore radius by the mercury intrusion method is that the lower limit is about 2 nm or more and the upper limit is about 200 μm or less, and the pores in a relatively large range compared to the nitrogen adsorption method described later. It can be said that it is suitable for analysis of distribution.
Measurement by the mercury intrusion method can be performed using an apparatus such as a mercury porosimeter. Specific examples of the mercury porosimeter include an autopore manufactured by Micromeritics, a pore master manufactured by Quantachrome, and the like.

Lithium transition metal based compound powder according to the present invention, in a mercury intrusion curve obtained by mercury intrusion porosimetry, mercury penetration amount at boosting the pressure 3.86kPa to 413MPa is, 0.4 cm ³ / g or more, 1.2 cm ³ / g or less is preferable.
Mercury intrusion volume is usually 0.4 cm ³ / g or more, preferably 0.45 cm ³ / g or more, more preferably 0.5 cm ³ / g or more, more preferably 0.55 cm ³ / g or more, and most preferably 0. 6 cm ³ / g or more, usually 1.2 cm ³ / g or less, preferably 1.1 cm ³ / g or less, more preferably 1.0 cm ³ / g or less, and most preferably 0.9 cm ³ / g or less. . When the upper limit of this range is exceeded, the voids become excessive, and when the particles of the present invention are used as the positive electrode material, the filling rate of the positive electrode active material into the positive electrode plate is lowered, and the battery capacity is restricted. On the other hand, if the lower limit of the range is not reached, voids between the particles become excessively small. Therefore, when a battery is produced using the particles of the present invention as a positive electrode material, lithium diffusion between the particles is inhibited and load characteristics are deteriorated. To do.

In the particles of the present invention, when a pore distribution curve is measured by a mercury intrusion method described later, a specific main peak described below usually appears.
In the present specification, the “pore distribution curve” refers to the total pore volume per unit weight (usually 1 g) of pores having a radius equal to or larger than the radius of the pores on the horizontal axis, The value obtained by differentiating the logarithm of the pore radius is plotted on the vertical axis, and is usually expressed as a graph connecting the plotted points. The pore distribution curve obtained by measuring the particles according to the present invention by the mercury intrusion method is referred to as “the pore distribution curve according to the present invention” as appropriate in the following description.

In this specification, “main peak” refers to the largest peak among the peaks of the pore distribution curve, and “sub peak” refers to peaks other than the main peak of the pore distribution curve.
In the present specification, “peak top” refers to the point at which the coordinate value of the vertical axis takes the largest value in each peak of the pore distribution curve.

<Main peak>
The main peak of the pore distribution curve according to the present invention has a peak top whose pore radius is usually 400 nm or more, preferably 600 nm or more, more preferably 700 nm or more, more preferably 800 nm or more, most preferably 900 nm or more, Moreover, it exists normally in 1500 nm or less, Preferably it is 1200 nm or less, More preferably, it is 1000 nm or less, More preferably, it is 980 nm or less, Most preferably, it exists in the range of 950 nm or less. When the upper limit of this range is exceeded, when a battery is produced using the porous particles of the present invention as a positive electrode material, lithium diffusion in the positive electrode material is inhibited, or the conductive path is insufficient, and load characteristics may be reduced. There is sex.

  On the other hand, below the lower limit of this range, when a positive electrode is produced using the porous particles of the present invention, the necessary amount of conductive material and binder increases, and the positive electrode plate (positive electrode current collector) is increased. The filling rate of the active material is restricted, and the battery capacity may be restricted. In addition, with the formation of fine particles, the mechanical properties of the coating film at the time of coating become hard or brittle, and there is a possibility that the coating film is likely to be peeled off during the winding process during battery assembly.

Further, the pore volume of the main peak included in the pore distribution curve according to the present invention is suitably usually 0.2 cm ³ / g or more, preferably 0.25 cm ³ / g or more, more preferably 0.3 cm ^3. / g or more, most preferably 0.32 cm ³ / g or more and usually 0.8 cm ³ / g or less, preferably 0.7 cm ³ / g or less, more preferably 0.6 cm ³ / g or less, and most preferably 0.5 cm ³ / g or less. When the upper limit of this range is exceeded, the voids become excessive, and when the particles of the present invention are used as the positive electrode material, the positive electrode active material filling rate into the positive electrode plate may be low, and the battery capacity may be limited. is there. On the other hand, if the lower limit of this range is not reached, voids between the particles become excessively small. Therefore, when a battery is produced using the particles of the present invention as a positive electrode material, lithium diffusion between secondary particles is inhibited, and load characteristics are reduced. May be reduced.

<Sub-peak>
The pore distribution curve according to the present invention may have a plurality of sub-peaks in addition to the main peak described above, and is particularly present in a pore radius range of 80 nm or more and less than 400 nm. To do.

In addition, the pore volume of the above-mentioned sub-peak included in the pore distribution curve according to the present invention is suitably usually 0.01 cm ³ / g or more, preferably 0.02 cm ³ / g or more, more preferably 0.03 cm. ³ / g or more, most preferably 0.04 cm ³ / g or more and usually 0.2 cm ³ / g or less, preferably 0.18 cm ³ / g or less, more preferably 0.15 cm ³ / g or less, and most preferably Is 0.1 cm ³ / g or less. If the upper limit of this range is exceeded, the voids between the secondary particles become excessive, and when the particles of the present invention are used as the positive electrode material, the positive electrode active material filling rate into the positive electrode plate becomes low, and the battery capacity is restricted. There is a possibility that. On the other hand, if the lower limit of this range is exceeded, voids between the secondary particles become excessively small, so when a battery is produced using the particles of the present invention as a positive electrode material, lithium diffusion between the secondary particles is inhibited, Load characteristics may be degraded.

<Bulk density>
The bulk density of the lithium transition metal compound powder of the present invention is usually 1.0 g / cm ³ or more, preferably 1.1 g / cm ³ or more, more preferably 1.3 g / cm ³ or more, most preferably 1.5 g. / Cm ³ or more. Below this lower limit, the powder filling property and electrode preparation may be adversely affected, and the positive electrode using this as an active material is usually 2.5 g / cm ³ or less, preferably 2.4 g / cm ³ or less, More preferably, it is 2.2 g / cm ³ or less, and most preferably 2.0 g / cm ³ or less. While the bulk density exceeding this upper limit is preferable for improving powder filling properties and electrode density, the specific surface area may become too low, and battery performance may be reduced.
In the present invention, the bulk density is obtained when 5 to 10 g of lithium nickel manganese cobalt composite oxide powder as a lithium transition metal compound powder is placed in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm. The powder packing density (tap density) of g / cm ³ was determined.

<Crystal structure>
The lithium transition metal-based compound powder of the present invention is preferably composed mainly of a lithium nickel manganese cobalt-based composite oxide including a crystal structure belonging to a layered structure.
Here, the layered structure will be described in more detail. As a typical crystal system having a layered structure, there are those belonging to the α-NaFeO ₂ type such as LiCoO ₂ and LiNiO ₂ , which are hexagonal and have a space group due to their symmetry.

(Hereinafter referred to as “layered R (−3) m structure”).
However, the layered LiMeO ₂ is not limited to the layered R (−3) m structure. This LiMnO ₂ also so-called layered Mn besides are layered compound space group Pm2m in orthorhombic, also, _Li 2 MnO ₃ so-called 213 _{phase, Li [Li} 1/3 _{Mn 2/3]} O ₂ , which is a monoclinic space group C2 / m structure, is also a layered compound in which a Li layer, a [Li _1/3 Mn _2/3 ] layer, and an oxygen layer are stacked.

<Powder X-ray diffraction peak>
In the present invention, the lithium nickel manganese cobalt based composite oxide powder having a composition satisfying the composition formulas (I) and (II) has a diffraction angle 2θ of 64.5 in a powder X-ray diffraction pattern using CuKα rays. It is characterized by being in the range of 0.1 ≦ FWHM (110) ≦ 0.3, where FWHM (110) is the half width derived from the CuKα1 line of the (110) diffraction peak existing around ˜65 ° To do. In general, since the half-value width of the X-ray diffraction peak is used as a measure of crystallinity, an extensive study was conducted on the correlation between crystallinity and battery performance. As a result, it was found that a battery having a FWHM (110) within a specified range expresses good battery performance.

  In the present invention, the FWHM (110) is usually 0.01 or more, preferably 0.05 or more, more preferably 0.10 or more, still more preferably 0.12 or more, most preferably 0.14 or more, usually 0.3. Hereinafter, it is preferably 0.28 or less, more preferably 0.25 or less, further preferably 0.23 or less, and most preferably 0.2 or less.

  In the present invention, the lithium nickel manganese cobalt composite oxide powder having a composition satisfying the composition formulas (I) and (II) has a diffraction angle 2θ of 64 in powder X-ray diffraction measurement using CuKα rays. In the (018) diffraction peak existing in the vicinity of ˜64.5 °, the (110) diffraction peak existing in the vicinity of 64.5 to 65 °, and the (113) diffraction peak existing in the vicinity of 68 to 68.5 °, respectively. When there is no foreign phase-derived diffraction peak on the high angle side of the peak top of the above, or when it has a foreign phase-derived diffraction peak, the integrated intensity ratio of the different phase peak to the diffraction peak of the original crystal phase is in the following range, respectively. It is preferable to be within.

0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.10
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.15
0 ≦ I ₁₁₃ ^* / I ₁₁₃ ≦ 0.30
(Here, I ₀₁₈ , I ₁₁₀ , and I ₁₁₃ represent the integrated intensities of the diffraction peaks, respectively (018), (110), and (113), and I ₀₁₈ ^* , I ₁₁₀ ^* , and I ₁₁₃ ^* are (018 ), (110), (113) represents the integrated intensity of a diffraction peak derived from a different phase appearing at a higher angle than the peak top of the diffraction peak.)

By the way, although the details of the causative substance of the diffraction peak derived from this heterogeneous phase are not clear, when a heterogeneous phase is included, the capacity, rate characteristics, cycle characteristics, etc. when it is made into a battery are lowered. For this reason, the diffraction peak may have a diffraction peak that does not adversely affect the battery performance of the present invention, but it is preferably a ratio in the above range, and the diffraction peak derived from a different phase with respect to each diffraction peak. The integrated intensity ratio is usually I ₀₁₈ ^* / I ₀₁₈ ≦ 0.10, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.15, I ₁₁₃ ^* / I ₁₁₃ ≦ 0.30, preferably I ₀₁₈ ^* / I ₀₁₈ ≦ 0. 08, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.13, I ₁₁₃ ^* / I ₁₁₃ ≦ 0.25, more preferably I ₀₁₈ ^* / I ₀₁₈ ≦ 0.06, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.10, I ₁₁₃ ^* / _{I 113} ≦ 0.23, more preferably ^{_{I 018 * / I 018 ≦ 0.04}} , I 110 * / I 110 ≦ 0.08, be a _{I 113 * /} I 113 ≦ 0.20 Most preferably it is particularly preferred no diffraction peaks derived from heterogeneous phases.

<Lattice constant>
The lithium transition metal compound powder of the present invention has a crystal structure including a layered R (-3) m structure, and its lattice constant is 2.860Å ≦ a ≦ 2.890Å, 14.200 ≦ c ≦ 14. It is preferably in the range of 280cm. In the present invention, the crystal structure and lattice constant can be obtained by powder X-ray diffraction measurement using CuKα rays.

  In the present invention, the lattice constant a (Å) is usually 2.860Å ≦ a ≦ 2.890Å, preferably 2.863Å ≦ a ≦ 2.885Å, more preferably 2.865Å ≦ a ≦ 2.880Å, particularly preferably. Is 2.870Å ≦ a ≦ 2.878Å, and the lattice constant c (Å) is usually 14.200Å ≦ c ≦ 14280Å, preferably 14.205Å ≦ c ≦ 14.278Å, more preferably 14.210Å. ≦ c ≦ 14.275Å, particularly preferably 14.212Å ≦ c ≦ 14.272Å.

  In addition, the lithium transition metal compound powder of the present invention is fired at a high temperature in an oxygen-containing gas atmosphere in order to enhance the crystallinity of the positive electrode active material, particularly a firing temperature of 1150-500 (1-xy) (where x Y is synonymous with x and y in the formula (II), and represents 0.1 ≦ x ≦ 0.4 and 0.15 ≦ y ≦ 0.25.) It is preferable. In particular, the lower limit of the specific firing temperature is usually 800 ° C. or higher, preferably 850 ° C. or higher, more preferably 900 ° C. or higher in the lithium nickel manganese cobalt-based composite oxide having the composition represented by the composition formula (I). More preferably, it is 950 ° C. or more, most preferably 975 ° C. or more, and the upper limit is 1200 ° C. or less, preferably 1175 ° C. or less, more preferably 1150 ° C. or less, and most preferably 1125 ° C. or less. If the firing temperature is too low, heterogeneous phases are mixed, and the lattice distortion increases without developing a crystal structure. Moreover, the specific surface area becomes too large. Conversely, if the firing temperature is too high, the primary particles grow excessively, sintering between the particles proceeds too much, and the specific surface area becomes too small.

<Reason why the lithium transition metal-based compound powder of the present invention provides the above effects>
The reason why the lithium transition metal-based compound powder of the present invention brings about the above-described effect is considered as follows.
That is, the lithium transition metal-based compound powder of the present invention is fired at a certain temperature or higher after adding a compound containing an element such as W in a layered lithium nickel manganese cobalt-based composite oxide having a specific composition region. Therefore, when the battery is manufactured using this, it can achieve an excellent balance of characteristics. Estimated.

[Method for producing lithium transition metal compound powder for positive electrode material of lithium secondary battery]
Below, the manufacturing method of the lithium transition metal type compound powder for lithium secondary battery positive electrode materials of this invention is demonstrated.

  The method for producing the lithium transition metal-based compound powder of the present invention is not limited to a specific production method, but lithium carbonate, Ni compound, Mn compound, Co compound, Mo, W, Nb, Ta, A slurry preparation step of obtaining a slurry in which a metal compound containing at least one element selected from Re is pulverized in a liquid medium and uniformly dispersing them, and a spray drying step of spray drying the obtained slurry And the manufacturing method of the lithium transition metal type compound powder for lithium secondary battery positive electrode materials of this invention including the baking process of baking the obtained spray-dried body is suitably manufactured.

<Slurry preparation process>
Of the raw material compounds used in the preparation of the slurry in the production of the lithium transition metal-based compound powder by the method of the present invention, Li ₂ CO ₃ is mainly used as the lithium compound, except that this is used alone. In addition, one or more different lithium compounds may be used in combination. Examples of the different lithium compounds include LiNO ₃ , LiNO ₂ , LiOH, LiOH.H ₂ O, LiH, LiF, LiCl, LiBr, LiI, CH ₃ OOLi, Li ₂ O, Li ₂ SO ₄ , dicarboxylic acid Li, and citrate. Examples include acid Li, fatty acid Li, and alkyl lithium.

Moreover, as a nickel compound, Ni (OH) ₂ , NiO, NiOOH, NiCO ₃ , 2NiCO ₃ .3Ni (OH) ₂ .4H ₂ O, NiC ₂ O ₄ .2H ₂ O, Ni (NO ₃ ) ₂ .6H ₂ O, NiSO ₄ , NiSO ₄ .6H ₂ O, nickel fatty acid, nickel halide and the like. Among these, Ni (OH) ₂ , NiO, NiOOH, NiCO ₃ , 2NiCO ₃ .3Ni (OH) ₂ .4H ₂ O, NiC are used in that no harmful substances such as SO _x and NO _X are generated during the firing process. Nickel compounds such as ₂ O ₄ .2H ₂ O are preferred. Further, from the viewpoint that it can be obtained as an industrial raw material at a low cost and from the viewpoint of high reactivity, Ni (OH) ₂ , NiO, NiOOH, NiCO ₃ , and further, a decomposition gas is generated at the time of firing. Ni (OH) ₂ , NiOOH, and NiCO ₃ are particularly preferable from the viewpoint of easily forming voids in the secondary particles. These nickel compounds may be used individually by 1 type, and may use 2 or more types together.

In addition, manganese compounds such as Mn ₂ O ₃ , MnO ₂ , Mn ₃ O ₄ , manganese oxide, MnCO ₃ , Mn (NO ₃ ) ₂ , MnSO ₄ , manganese acetate, manganese dicarboxylate, manganese citrate, fatty acid manganese And manganese salts such as oxyhydroxide, manganese chloride and the like. Among these manganese compounds, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , and MnCO ₃ do not generate gases such as SO _x and NO _x during firing, and can be obtained at low cost as industrial raw materials. Therefore, it is preferable. Furthermore, these manganese compounds may be used individually by 1 type, and may use 2 or more types together.

Further, as the cobalt compound, Co (OH) ₂ , CoOOH, CoO, Co ₂ O ₃ , Co ₃ O ₄ , Co (OCOCH ₃ ) ₂ .4H ₂ O, CoCl ₂ , Co (NO ₃ ) ₂ .6H ₂ O, Co (SO ₄ ) ₂ · 7H ₂ O, CoCO _{3 and the} like. Among them, Co (OH) ₂ , CoOOH, CoO, Co ₂ O ₃ , Co ₃ O ₄ , and CoCO ₃ are preferable, and more preferably, from the viewpoint that no harmful substances such as SO _x and NO _X are generated during the firing process. Co (OH) ₂ and CoOOH are industrially inexpensively available and highly reactive. In addition, Co (OH) ₂ , CoOOH, and CoCO ₃ are particularly preferable from the viewpoint of easily forming voids in the secondary particles of the spray-dried powder due to generation of decomposition gas during firing. These cobalt compounds may be used individually by 1 type, and may use 2 or more types together.

In addition, as the compound of Mo, W, Nb, Ta, and Re, there is no particular limitation on the type, but an oxide is usually used. Is exemplified _{compounds, MoO, MoO 2, MoO 3} , MoO x, Mo 2 O 3, Mo 2 O 5, Li 2 MoO 4, WO, WO 2, WO 3, WO x, W 2 O 3, W 2 O ₅ , W ₁₈ O ₄₉ , W ₂₀ O ₅₈ , W ₂₄ O ₇₀ , W ₂₅ O ₇₃ , W ₄₀ O ₁₁₈ , Li ₂ WO ₄ , NbO, NbO ₂ , Nb ₂ O, Nb ₂ O ₅ , Nb ₄ O , Nb ₆ O, LiNbO ₃ , TaO, TaO ₂ , Ta ₂ O ₅ , LiTaO ₃ , ReO ₂ , ReO ₃ , Re ₂ O _{3 and the} like, preferably MoO ₃ , Li ₂ MoO ₄ , WO ₃ , Li ₂ WO ₄ , LiNbO ₃ , Ta ₂ O ₅ , LiTaO ₃ and ReO ₃ are mentioned, and particularly preferred are WO ₃ , Li ₂ WO ₄ , Ta ₂ O ₅ and ReO ₃ . These compounds may be used individually by 1 type, and may use 2 or more types together.

  In addition to the above Li, Ni, Mn, and Co raw material compounds, it is possible to use a compound group for the purpose of introducing the above-mentioned foreign elements by performing substitution of other elements.

The raw material mixing method is not particularly limited as long as it is a method capable of highly uniform mixing, and may be dry or wet. For example, a method using an apparatus such as a ball mill, a vibration mill, or a bead mill can be used. Wet mixing in which the raw material compound is mixed in a liquid medium such as water or alcohol is preferable because more uniform mixing is possible and the reactivity of the mixture can be increased in the firing step. Furthermore, in the present invention, it is important to finely and highly uniformly mix the raw material compound and a different element such as Mo, W, Nb, Ta, and Re together by wet pulverization.
The mixing time varies depending on the mixing method, but it is sufficient that the raw materials are uniformly mixed at the particle level. For example, in a ball mill (wet or dry type), usually about 1 to 2 days, and in a bead mill (wet continuous method), a residence time. Is usually about 0.1 to 6 hours.

  In the raw material mixing stage, it is preferable that the raw material is pulverized in parallel. As the degree of pulverization, the particle diameter of the raw material particles after pulverization is an index, but the average particle diameter (median diameter) is usually 0.5 μm or less, preferably 0.4 μm or less, more preferably 0.35 μm or less, most preferably Preferably, it is 0.3 μm or less. If the average particle size of the pulverized raw material particles is too large, the reactivity in the firing process is lowered, and the composition is difficult to homogenize. However, making particles smaller than necessary leads to an increase in pulverization cost, so that the average particle size is usually 0.01 μm or more, preferably 0.1 μm or more, more preferably 0.2 μm or more. It ’s fine. A means for realizing such a degree of pulverization is not particularly limited, but a wet pulverization method is preferable. Specific examples include dyno mill.

  In the present invention, the median diameter of the pulverized particles in the slurry was measured with a known laser diffraction / scattering type particle size distribution measuring apparatus with a refractive index of 1.24 and a particle diameter standard set as a volume standard. Is. In the present invention, a 0.1 wt% sodium hexametaphosphate aqueous solution was used as a dispersion medium used in the measurement, and measurement was performed after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz). The median diameter of the spray-dried body described later is the same as that except that the measurement was performed after ultrasonic dispersion for 0, 1, 3, and 5 minutes, respectively.

<Spray drying process>
After the wet mixing, it is then usually subjected to a drying process. The drying method is not particularly limited, but spray drying is preferable from the viewpoints of uniformity of the generated particulate matter, powder fluidity, powder handling performance, and efficient production of dry particles.

<Spray-dried powder>
In the method for producing lithium transition metal-based compound powder such as lithium nickel manganese cobalt-based composite oxide powder of the present invention, the slurry obtained by wet-grinding the raw material compound and the additive is spray-dried, A powder obtained by agglomerating primary particles to form secondary particles is obtained. The spray-dried powder formed by agglomerating primary particles to form secondary particles is a geometric feature of the spray-dried powder of the present invention. Examples of the shape confirmation method include SEM observation and cross-sectional SEM observation.

  The median diameter (value measured without applying ultrasonic dispersion) of the powder obtained by spray drying, which is also a firing precursor of the lithium nickel manganese cobalt based composite oxide powder of the present invention, is usually 22 μm or less, more preferably. Is 17 μm or less, more preferably 12 μm or less, more preferably 11 μm or less, and most preferably 10 μm or less. However, since it tends to be difficult to obtain a too small particle size, it is usually 3 μm or more, preferably 4 μm or more, more preferably 5 μm or more. In the case of producing a particulate material by the spray drying method, the particle size can be controlled by appropriately selecting the spray format, the pressurized gas flow supply rate, the slurry supply rate, the drying temperature, and the like.

  In other words, lithium carbonate, nickel compound, manganese compound, cobalt compound, and metal compound containing at least one element selected from W, Nb, Ta, Re are pulverized and mixed until the median diameter becomes 0.5 μm or less. Then, after the slurry uniformly dispersed in the liquid medium is spray-dried, the powder obtained is fired to produce a lithium nickel manganese cobalt based composite oxide powder. ), When the slurry supply amount is S (L / min) and the gas supply amount is G (L / min), the slurry viscosity V is 50 cp ≦ V ≦ 4000 cp, and the gas-liquid ratio G / S is And spray drying under the condition of 500 ≦ G / S ≦ 10000.

  If the slurry viscosity V (cp) is too low, it may be difficult to obtain a powder obtained by agglomerating primary particles to form secondary particles. If the slurry viscosity V (cp) is too high, the supply pump may fail or the nozzle may be blocked. is there. Therefore, the slurry viscosity V (cp) is usually 50 cp or more as a lower limit, preferably 100 cp or more, more preferably 300 cp or more, most preferably 500 cp, and the upper limit is usually 4000 cp or less, preferably 3500 cp or less. Is 3000 cp or less, most preferably 2500 cp or less.

  Moreover, when gas-liquid ratio G / S is less than the said minimum, there exists a possibility that drying property may fall easily, and when it exceeds an upper limit, there exists a possibility that production efficiency may fall. Therefore, the gas-liquid ratio G / S is usually 500 or more, preferably 800 or more, more preferably 1000 or more, most preferably 1500 or more as the lower limit, and usually 10,000 or less, preferably 9000 or less, as the upper limit. Preferably it is 8000 or less, most preferably 7500 or less.

  The slurry supply amount S and the gas supply amount G are appropriately set according to the viscosity of the slurry used for spray drying, the specifications of the spray drying apparatus used, and the like.

  In the method of the present invention, the above-mentioned gas-liquid ratio G / S is satisfied by controlling the slurry supply amount and gas supply amount that meet the above-mentioned slurry viscosity V (cp) and that are suitable for the specifications of the spray drying apparatus to be used. Spray drying may be performed within a range, and other conditions are appropriately set according to the type of apparatus to be used, but it is preferable to select the following conditions.

  That is, spray drying of the slurry is usually 50 ° C. or higher, preferably 70 ° C. or higher, more preferably 120 ° C. or higher, most preferably 140 ° C. or higher, usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 230. It is preferable to carry out at a temperature of not higher than ℃, most preferably not higher than 200 ℃. If this temperature is too high, the resulting granulated particles may have a lot of hollow structures, which may reduce the packing density of the powder. On the other hand, if it is too low, problems such as powder sticking and blockage due to moisture condensation at the powder outlet may occur.

In addition, spray-dried powders of lithium transition metal-based compound powders such as lithium nickel manganese cobalt-based composite oxide powders according to the present invention are characterized by weak cohesion between primary particles, and are suitable for ultrasonic dispersion. This can be confirmed by examining the degree of change in the median diameter. For example, the ratio of the median diameter _D 50 that is measured without ultrasonic dispersion [US0 minutes] 5 minutes median diameter _D 50 measured after ultrasonic dispersion [US5 min] for _{(μm) (μm): D} 50 [ When expressed as US5] / D ₅₀ [US0], the lower limit is usually 0.03 or more, preferably 0.05 or more, more preferably 0.07 or more, and the upper limit is 0.7 or less, preferably 0.8. 6 or less, more preferably 0.5 or less. _{D 50 [US5] / D 50} [US0] is above a value larger than the spray-dried particles of lithium transition metal-based compound particles calcined using a result of the air gap is reduced in the secondary particle, the output characteristics are degraded There is a fear. On the other _{hand, D 50 [US5] / D} 50 [US0] is above values lithium nickel was fired using a smaller spray-dried particles manganese cobalt-based composite oxide particles, too many voids between the particles, the bulk density There is a possibility that problems such as lowering of the coating speed and deterioration of the coating properties are likely to occur.

In addition, if the specific surface area of the powder obtained by spray drying is low, the reactivity decreases during the firing reaction. Therefore, as described above, the powder is obtained as high as possible by means such as pulverizing the starting material before spray drying. It is preferable to have a specific surface area. On the other hand, excessively high specific surface area is not only industrially disadvantageous, but also may result in failure to obtain the lithium transition metal compound of the present invention. Accordingly, the spray-dried particles thus obtained have a BET specific surface area of usually 10 m ² / g or more, preferably 30 m ² / g or more, more preferably 50 m ² / g or more, most preferably 60 m ² / g or more. Usually, it is preferably 100 m ² / g or less, preferably 90 m ² / g or less, more preferably 80 m ² / g or less, and most preferably 75 m ² / g or less.

<Baking process>
The fired precursor thus obtained is then fired.
Here, the “firing precursor” in the present invention means a precursor of a lithium transition metal compound such as a lithium nickel manganese cobalt composite oxide before firing obtained by treating a spray-dried powder. For example, the above spray-dried powder may contain a compound that generates or sublimates decomposition gas during the above-described firing to form voids in the secondary particles, and serves as a firing precursor.

  This firing condition depends on the composition and the type of raw material compound used, but as a tendency, if the firing temperature is too high, primary particles grow excessively, sintering between the particles proceeds too much, and the specific surface area decreases. Pass. On the other hand, if it is too low, heterogeneous phases are mixed, and the lattice distortion increases without developing the crystal structure. Moreover, the specific surface area becomes too large. The firing temperature is usually 800 ° C. or higher, preferably 850 ° C. or higher, more preferably 900 ° C. or higher, further preferably 950 ° C. or higher, most preferably 975 ° C. or higher in the composition represented by the formula (I). It is usually 1200 ° C. or lower, preferably 1175 ° C. or lower, more preferably 1150 ° C. or lower, and most preferably 1125 ° C. or lower.

  For firing, for example, a box furnace, a tubular furnace, a tunnel furnace, a roller hearth furnace, a rotary kiln or the like can be used. The firing process is usually divided into three parts: temperature increase, maximum temperature retention, and temperature decrease. The second maximum temperature holding portion is not necessarily limited to one time, and may include two or more stages depending on the purpose, which means that aggregation is eliminated to the extent that secondary particles are not destroyed. The temperature raising, maximum temperature holding, and temperature lowering steps may be repeated twice or more with a crushing step or a pulverization step which means crushing to primary particles or even fine powder.

  In the temperature raising step, the temperature in the furnace is usually raised at a temperature raising rate of 0.1 ° C./min to 10 ° C./min. Even if this rate of temperature rise is too slow, it takes time and is industrially disadvantageous. However, if it is too fast, the furnace temperature does not follow the set temperature depending on the furnace. The temperature rising rate is preferably 0.5 ° C./min or more, more preferably 1 ° C./min or more, further preferably 1.5 ° C./min or more, preferably 8 ° C./min or less, more preferably 6 ° C./min. Min. Or less, more preferably 4 ° C./min or less.

  The holding time in the maximum temperature holding step varies depending on the temperature, but usually 30 minutes or longer, preferably 1 hour or longer, more preferably 2 hours or longer, more preferably 3 hours or longer, most preferably within the above-mentioned temperature range. Is 5 hours or more, 50 hours or less, preferably 25 hours or less, more preferably 20 hours or less, further preferably 15 hours or less, more preferably 10 hours or less, and most preferably 8 hours or less. If the firing time is too short, it becomes difficult to obtain a lithium nickel manganese cobalt based composite oxide powder with good crystallinity, and it is not practical to be too long. If the firing time is too long, it will be disadvantageous because it will be necessary to crush afterwards or it will be difficult to crush.

  In the temperature lowering step, the temperature in the furnace is normally decreased at a temperature decreasing rate of 0.1 ° C./min to 10 ° C./min. If it is too slow, it takes time and is industrially disadvantageous. However, if it is too fast, the uniformity of the target product tends to be lacking or the deterioration of the container tends to be accelerated. The temperature lowering rate is preferably 1 ° C./min or more, more preferably 3 ° C./min or more, preferably 7 ° C./min or less, more preferably 5 ° C./min or less.

  The atmosphere during firing is an oxygen-containing gas atmosphere, but since there is an appropriate oxygen partial pressure region corresponding to the composition of the lithium transition metal compound powder to be obtained, various gas atmospheres suitable for satisfying it Is used. Examples of the gas atmosphere include oxygen, air, or a mixed gas having an arbitrary ratio of oxygen or air and an inert gas such as nitrogen or argon. Usually, the atmosphere has an oxygen concentration of 1% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and 100% by volume or less, preferably 50% by volume or less, more preferably 25% by volume or less.

  In such a production method, in order to produce the lithium transition metal compound powder of the present invention, lithium carbonate, nickel compound, manganese compound, cobalt compound, and Mo, W, When preparing a slurry in which at least one metal compound selected from Nb, Ta, and Re is dispersed in a liquid medium, the target molar ratio is controlled by adjusting the mixing ratio of each compound. Can do.

<Classification process>
The fired powder obtained by firing is then classified in order to crush it, adjust it to a particle size distribution preferable for electrode preparation, or remove coarse foreign matters and the like. The classification method is not particularly limited as long as the object can be achieved, and examples thereof include sieve classification (vibrating sieve, centrifugal sieve), and pneumatic classification. Specific examples of the apparatus include Dalton's “Ultrasonic Vibrating Sieve”, Tsukasa Industries '“Powder Footer”, Turbo Industries' “Turbo Screener”, Hosokawa Micron's “Turboplex”, and the like. However, it is not limited to these.

  According to the lithium transition metal-based compound powder of the present invention thus obtained, a positive electrode material for a lithium secondary battery with high capacity, excellent output characteristics and life characteristics, and a good performance balance is provided.

[Positive electrode for lithium secondary battery]
The positive electrode for a lithium secondary battery of the present invention is obtained by forming a positive electrode active material layer containing a lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention and a binder on a current collector. It is. Here, as the positive electrode material, only one kind of the lithium transition metal compound powder of the present invention may be used, or two or more kinds may be mixed and used, or the lithium transition metal compound of the present invention may be used. You may mix and use 1 or more types of powder, and 1 or more types of the other positive electrode active material powder. When the lithium transition metal-based compound powder of the present invention is used in combination with the other positive electrode active material, the lithium transition metal-based compound of the present invention is used in order to obtain a sufficient effect by the lithium transition metal-based compound powder of the present invention. The ratio of the lithium transition metal based compound powder of the present invention to the total of the compound powder and the other positive electrode active material is preferably 15% by weight or more, and preferably 30% by weight or more. Is more preferable, and 50% by weight or more is most preferable.

  The positive electrode active material layer is usually formed by mixing a positive electrode material, a binder, and a conductive material and a thickener, which are used if necessary, in a dry form into a sheet shape, and then pressing the positive electrode current collector on the positive electrode current collector. Alternatively, these materials are dissolved or dispersed in a liquid medium to form a slurry, which is applied to the positive electrode current collector and dried.

  As the material for the positive electrode current collector, metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and carbon materials such as carbon cloth and carbon paper are usually used. Of these, metal materials are preferable, and aluminum is particularly preferable. As for the shape, in the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder Etc. Among these, metal thin films are preferable because they are currently used in industrialized products. In addition, you may form a thin film suitably in mesh shape.

  When a thin film is used as the positive electrode current collector, its thickness is arbitrary, but it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 100 mm or less, preferably 1 mm or less, more preferably 50 μm or less. The range of is preferable. If it is thinner than the above range, the strength required for the current collector may be insufficient. On the other hand, if it is thicker than the above range, the handleability may be impaired.

  The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of a coating method, any material that is stable with respect to the liquid medium used during electrode production may be used. Specific examples include polyethylene, Resin polymers such as polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitrocellulose, SBR (styrene butadiene rubber), NBR (acrylonitrile butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene・ Rubber polymers such as propylene rubber, styrene / butadiene / styrene block copolymers and hydrogenated products thereof, EPDM (ethylene / propylene / diene terpolymers), styrene / ethylene / butadiene / ethylene copolymers, Styrene / isoprene styrene bromide Such as thermoplastic elastomeric polymers such as copolymer and hydrogenated products thereof, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer, etc. Fluorine polymers such as soft resin-like polymers, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers, ion conductivity of alkali metal ions (especially lithium ions) And a polymer composition having the same. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  The ratio of the binder in the positive electrode active material layer is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more, and usually 80% by weight or less, preferably 60% by weight or less. More preferably, it is 40% by weight or less, and most preferably 10% by weight or less. If the proportion of the binder is too low, the positive electrode active material cannot be sufficiently retained and the positive electrode has insufficient mechanical strength, which may deteriorate battery performance such as cycle characteristics. Battery capacity and conductivity may be reduced.

  The positive electrode active material layer usually contains a conductive material in order to increase conductivity. There are no particular restrictions on the type, but specific examples include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. And carbon materials. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios. The proportion of the conductive material in the positive electrode active material layer is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 1% by weight or more, and usually 50% by weight or less, preferably 30%. % By weight or less, more preferably 20% by weight or less. If the proportion of the conductive material is too low, the conductivity may be insufficient, and conversely if it is too high, the battery capacity may be reduced.

  As a liquid medium for forming a slurry, it is possible to dissolve or disperse a lithium transition metal compound powder as a positive electrode material, a binder, and a conductive material and a thickener used as necessary. If it is a solvent, there is no restriction | limiting in particular in the kind, You may use either an aqueous solvent or an organic solvent. Examples of the aqueous solvent include water and alcohol. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran (THF), toluene, acetone, dimethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, etc. be able to. In particular, when an aqueous solvent is used, a dispersant is added together with the thickener, and a slurry such as SBR is slurried. In addition, these solvents may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The content of the lithium transition metal-based compound powder of the present invention as the positive electrode material in the positive electrode active material layer is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and usually 99%. .9% by weight or less, preferably 99% by weight or less. If the proportion of the lithium transition metal compound powder in the positive electrode active material layer is too large, the strength of the positive electrode tends to be insufficient, and if it is too small, the capacity may be insufficient.

  The thickness of the positive electrode active material layer is usually about 10 to 200 μm.

The positive electrode active material layer obtained by coating and drying is preferably consolidated by a roller press or the like in order to increase the packing density of the positive electrode active material.
Thus, the positive electrode for a lithium secondary battery of the present invention can be adjusted.

[Lithium secondary battery]
The lithium secondary battery of the present invention includes a positive electrode for a lithium secondary battery according to the present invention that can occlude and release lithium, a negative electrode that can occlude and release lithium, and a non-aqueous electrolyte that uses a lithium salt as an electrolytic salt. Prepare. Further, a separator for holding a nonaqueous electrolyte may be provided between the positive electrode and the negative electrode. In order to effectively prevent a short circuit due to contact between the positive electrode and the negative electrode, it is desirable to interpose a separator in this way.

<Negative electrode>
The negative electrode is usually configured by forming a negative electrode active material layer on a negative electrode current collector, similarly to the positive electrode.
As a material of the negative electrode current collector, a metal material such as copper, nickel, stainless steel, nickel-plated steel, or a carbon material such as carbon cloth or carbon paper is used. Among these, in the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder, etc. are mentioned. Among these, metal thin films are preferable because they are currently used in industrialized products. In addition, you may form a thin film suitably in mesh shape. When a metal thin film is used as the negative electrode current collector, the preferred thickness range is the same as the range described above for the positive electrode current collector.

  The negative electrode active material layer includes a negative electrode active material. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions, but it can usually occlude and release lithium from the viewpoint of high safety. A carbon material is used.

  Although there is no restriction | limiting in particular as a carbon material, The graphite (graphite), such as artificial graphite and natural graphite, and the thermal decomposition thing of organic substance on various thermal decomposition conditions are mentioned. Examples of pyrolysis products of organic matter include coal-based coke, petroleum-based coke, coal-based pitch carbide, petroleum-based pitch carbide, or carbide obtained by oxidizing these pitches, needle coke, pitch coke, phenol resin, crystalline cellulose, etc. And carbon materials obtained by partially graphitizing these, furnace black, acetylene black, pitch-based carbon fibers, and the like. Among them, graphite is preferable, and particularly preferable is artificial graphite, purified natural graphite, or graphite material containing pitch in these graphites manufactured by subjecting easy-graphite pitch obtained from various raw materials to high-temperature heat treatment. Therefore, those subjected to various surface treatments are mainly used. One of these carbon materials may be used alone, or two or more thereof may be used in combination.

When a graphite material is used as the negative electrode active material, the d value (interlayer distance: d ₀₀₂ ) of the lattice plane (002 plane) determined by X-ray diffraction by the Gakushin method is usually 0.335 nm or more, and usually 0.34 nm. In the following, it is preferable that the thickness is 0.337 nm or less.

  Further, the ash content of the graphite material is usually 1% by weight or less, particularly 0.5% by weight or less, and particularly preferably 0.1% by weight or less, based on the weight of the graphite material.

Further, the crystallite size (L _c ) of the graphite material determined by X-ray diffraction by the Gakushin method is usually 30 nm or more, preferably 50 nm or more, particularly preferably 100 nm or more.

  The median diameter of the graphite material determined by the laser diffraction / scattering method is usually 1 μm or more, especially 3 μm or more, more preferably 5 μm or more, especially 7 μm or more, and usually 100 μm or less, especially 50 μm or less, more preferably 40 μm or less, especially 40 μm or less. It is preferable that it is 30 micrometers or less.

Moreover, the BET specific surface area of the graphite material is usually 0.5 m ² / g or more, preferably 0.7 m ² / g or more, more preferably 1.0 m ² / g or more, and further preferably 1.5 m ² / g. or more, and usually 25.0 m ² / g or less, preferably 20.0 m ² / g, more preferably 15.0 m ² / g or less, still more preferably 10.0 m ² / g or less.

Further, when performing Raman spectroscopy using argon laser light for graphite material, and strength _{I A} of the peak PA detected in the range of 1580～1620Cm ^-1, is detected in the range of 1350 ^-1 It is preferable that the intensity ratio I _A / I _B of the peak P _{B with} the intensity I _B is 0 or more and 0.5 or less. Further, the half width of the peak _{P A} is preferably 26cm ^-1 or less, 25 cm ^-1 or less is more preferable.

In addition to the above-mentioned various carbon materials, it can also be used as a negative electrode active material of other materials capable of inserting and extracting lithium. Specific examples of negative electrode active materials other than carbon materials include metal oxides such as tin oxide and silicon oxide, nitrides such as Li _2.6 Co _0.4 N, and lithium alloys such as lithium alone and lithium aluminum alloys. Can be mentioned. One of these materials other than the carbon material may be used alone, or two or more thereof may be used in combination. Moreover, you may use in combination with the above-mentioned carbon material.

  As in the case of the positive electrode active material layer, the negative electrode active material layer is usually prepared by slurrying the above-described negative electrode active material, a binder, and optionally a conductive material and a thickener in a liquid medium. It can manufacture by apply | coating to a negative electrode electrical power collector, and drying. As the liquid medium, the binder, the thickener, the conductive material, and the like that form the slurry, the same materials as those described above for the positive electrode active material layer can be used.

<Nonaqueous electrolyte>
As the non-aqueous electrolyte, for example, known organic electrolytes, polymer solid electrolytes, gel electrolytes, inorganic solid electrolytes, and the like can be used. Of these, organic electrolytes are preferable. The organic electrolytic solution is configured by dissolving a solute (electrolyte) in an organic solvent.

  Here, the type of the organic solvent is not particularly limited. For example, carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, chlorinated hydrocarbons, ethers, amines, esters, amides. A phosphoric acid ester compound or the like can be used. Typical examples include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, ethylene carbonate, vinylene carbonate, vinyl ethylene carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 4-methyl-2- Pentanone, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile Benzonitrile, butyronitrile, valeronitrile, 1,2-dichloroethane, dimethylformamide, dimethyl sulfoxide, trimethyl phosphate, triethyl phosphate, etc. Et compounds, hydrogen atoms may be partially substituted with a halogen atom. Moreover, these single or 2 or more types of mixed solvents can be used.

  The organic solvent described above preferably contains a high dielectric constant solvent in order to dissociate the electrolytic salt. Here, the high dielectric constant solvent means a compound having a relative dielectric constant of 20 or more at 25 ° C. Among the high dielectric constant solvents, it is preferable that ethylene carbonate, propylene carbonate, and compounds in which hydrogen atoms thereof are substituted with other elements such as halogen or alkyl groups are contained in the electrolytic solution. The proportion of the high dielectric constant solvent in the electrolyte is preferably 20% by weight or more, more preferably 25% by weight or more, and most preferably 30% by weight or more. If the content of the high dielectric constant solvent is less than the above range, desired battery characteristics may not be obtained.

In addition, in the organic electrolyte, a gas such as CO ₂ , N ₂ O, CO, and SO ₂ , vinylene carbonate, polysulfide S _x ^{2−, and the} like that enables efficient charge and discharge of lithium ions on the negative electrode surface You may add the additive which forms a film in arbitrary ratios. Among these additives, vinylene carbonate is particularly preferable.

  Furthermore, an additive that exhibits an effect of improving cycle life and output characteristics, such as lithium difluorophosphate, may be added to the organic electrolyte at an arbitrary ratio.

The type of the electrolytic salt is not particularly limited, and any conventionally known solute can be used. Specific examples include LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiBOB, LiCl, LiBr, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , LiN (SO ₃ CF ₃ ) _{2 and the} like. Any one of these electrolytic salts may be used alone, or two or more thereof may be used in any combination and ratio.

  The lithium salt of the electrolytic salt is usually contained in the electrolytic solution so as to have a concentration of 0.5 mol / L to 1.5 mol / L. Even if the lithium salt concentration in the electrolytic solution is less than 0.5 mol / L or more than 1.5 mol / L, the electric conductivity may be lowered, and the battery characteristics may be adversely affected. The lower limit of this concentration is preferably 0.75 mol / L or more and the upper limit is 1.25 mol / L or less.

Even when a polymer solid electrolyte is used, the type thereof is not particularly limited, and any known crystalline / amorphous inorganic substance can be used as the solid electrolyte. Examples of the crystalline inorganic solid electrolyte include LiI, Li ₃ N, Li _{1 + x} J _x Ti _2-x (PO ₄ ) ₃ (J = Al, Sc, Y, La), Li _0.5-3x RE _{0. .5 + x} TiO ₃ (RE = La, Pr, Nd, Sm) and the like. Examples of the amorphous inorganic solid electrolyte include oxide glasses such as 4.9LiI-34.1Li ₂ O-61B ₂ O ₅ and 33.3Li ₂ O-66.7SiO ₂ . Any one of these may be used alone, or two or more may be used in any combination and ratio.

<Separator>
When the above-described organic electrolyte is used as the electrolyte, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit between the electrodes. The material and shape of the separator are not particularly limited, but those that are stable with respect to the organic electrolyte used, have excellent liquid retention properties, and can reliably prevent short-circuiting between electrodes are preferable. Preferable examples include microporous films, sheets, nonwoven fabrics and the like made of various polymer materials. Specific examples of the polymer material include polyolefin polymers such as nylon, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene, and polybutene. In particular, from the viewpoint of chemical and electrochemical stability, which is an important factor for separators, polyolefin polymers are preferable. From the viewpoint of self-occluding temperature, which is one of the purposes of use of separators in batteries, polyethylene is preferred. Is particularly desirable.

  When using a separator made of polyethylene, it is preferable to use ultra-high molecular weight polyethylene from the viewpoint of maintaining high-temperature shape, and the lower limit of the molecular weight is preferably 500,000, more preferably 1,000,000, and most preferably 1,500,000. On the other hand, the upper limit of the molecular weight is preferably 5 million, more preferably 4 million, and most preferably 3 million. This is because if the molecular weight is too large, the fluidity becomes too low, and the pores of the separator may not close when heated.

<Battery shape>
The lithium secondary battery of the present invention is produced by assembling the above-described positive electrode for a lithium secondary battery of the present invention, a negative electrode, an electrolyte, and a separator used as necessary into an appropriate shape. Furthermore, other components such as an outer case can be used as necessary.

  The shape of the lithium secondary battery of the present invention is not particularly limited, and can be appropriately selected from various commonly employed shapes according to the application. Examples of commonly used shapes include a cylinder type with a sheet electrode and separator in a spiral shape, a cylinder type with an inside-out structure combining a pellet electrode and a separator, and a coin type with stacked pellet electrodes and a separator. Can be mentioned. The method for assembling the battery is not particularly limited, and can be appropriately selected from various commonly used methods according to the shape of the target battery.

  The general embodiment of the lithium secondary battery of the present invention has been described above. However, the lithium secondary battery of the present invention is not limited to the above-described embodiment, and various modifications are possible as long as the gist thereof is not exceeded. Can be implemented.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

[Measurement method of physical properties]
The physical properties and the like of lithium transition metal-based compound powders produced in each Example and Comparative Example described below were measured as follows.

<Average primary particle size>
The comparison example 2 was obtained from an SEM image of 3,000 times, the comparative example 5 was obtained from a 10,000 times image, and the others were obtained from a 30,000 times image.

<Secondary particle size>
The median diameter of secondary particles was measured after 5 minutes of ultrasonic dispersion.

<Bulk density>
4 to 10 g of the sample powder was put into a 10 ml glass graduated cylinder, and the powder packing density when tapped 200 times with a stroke of about 20 mm was obtained.

<Measurement of various physical properties by mercury intrusion method>
As a measuring device by the mercury intrusion method, Autopore III9420 manufactured by Micromeritics was used. Moreover, as measurement conditions of the mercury intrusion method, measurement was performed while increasing the pressure from 3.86 kPa to 413 MPa at room temperature. The mercury surface tension value was 480 dyn / cm, and the contact angle value was 141.3 °.

<Specific surface area>
Obtained by BET method.

<Volume resistivity>
Using a powder resistivity measurement device (Dia Instruments: Lorester GP powder low efficiency measurement system PD-41), the sample weight is 2 g, and a powder probe unit (four probe / ring electrode, electrode spacing 5.0 mm) , Electrode radius 1.0 mm, sample radius 12.5 mm), the applied voltage limiter is 90 V, the volume resistivity [Ω · cm] of the powder under various pressures is measured, and the volume resistivity under a pressure of 40 MPa is measured. The values were compared.

<Composition (Li / Ni / Mn / Co)>
It was determined by ICP-AES analysis.

<Quantification of additive elements (W, Ta) and foreign elements (B)>
It was determined by ICP-AES analysis.

<SERS measurement>
Device: Thermo Fisher Scientific's Nicolet
Almega XR
Pretreatment: Silver deposition (10nm)
Excitation wavelength: 532 nm
Excitation output: 0.5 mW or less at the sample position Analysis method: Measure the height and half-value width excluding the linear background from each peak Spectral resolution: 10 cm ⁻¹

<IR spectrum measurement>
Device: Nicolet Magna 560
Measurement method: Transmission method (KBr)
Resolution: 4cm ^-1
Number of integrations: 100 Sample preparation method: Weigh 0.5mg of sample and 0.2g of KBr and mix quickly in a mortar.
Put the total amount of the mixed powder into a φ10mm press jig and place 8ton
Molded with pressure.

<Composition analysis of primary particle surface by X-ray photoelectron spectroscopy (XPS)>
(XPS measurement)
The measurement was performed under the following conditions using an X-ray photoelectron spectrometer “ESCA-5700” manufactured by Physical Electronics.
X-ray source: Monochromatic AlKα
Analysis area: 0.8mm diameter Extraction angle: 65 °
Quantitative method: B1s, Mn2p1 _{/ 2} , Co2p3 _{/ 2} , Ni2p3 _{/ 2} , W4f,
Ta4f
The area of each peak is corrected with a sensitivity coefficient.
(Surface sputtering)
Ion species: Ar
Acceleration voltage: 3 kV
Ion current: 4.7 nA (Examples 1 to 5, Comparative Example 3)
6.9 nA (Examples 6 and 7)
6.6 nA (Comparative Example 1)
Sputtering rate:
2.91 nm / min (SiO ₂ equivalent) (Examples 1 to 5, Comparative Example 3)
2.31 nm / min (in terms of SiO ₂ ) (Examples 6 and 7)
2.29 nm / min (in terms of SiO ₂ ) (Comparative Example 1)

<Contained carbon concentration C>
An EMIA-520 carbon sulfur analyzer manufactured by HORIBA, Ltd. was used. A sample of several tens to 100 mg was weighed into an air-baked magnetic crucible, a combustion aid was added, and carbon was extracted by combustion in a high-frequency heating furnace in an oxygen stream. CO ₂ in the combustion gas was quantified by non-dispersive infrared absorption spectrophotometry. For sensitivity calibration, 150-15 low alloy steel No. 1 (C guaranteed value: 0.469% by weight) manufactured by Japan Iron and Steel Federation was used.

<Confirmation of crystal phase (layered structure), measurement of half-width FWHM (110), (018), (110), (113) Confirmation of presence / absence of heterophase peak in diffraction peak and heterophase peak / original crystal phase peak Calculation of integral intensity and integral intensity ratio>
It calculated | required by the powder X-ray-diffraction measurement using the CuK (alpha) ray described below. The measurement was performed in the variable slit mode, and the intensity was converted to the intensity when the fixed slit was used according to the formula of intensity (fixed) = intensity (variable) / sin θ. Profile fitting was performed on the (018), (110), and (113) diffraction peaks derived from the hexagonal R-3m (No. 166) observed in each sample, and the peak half-value width FWHM derived from CuKα1 (110) The integrated intensity and the integrated intensity ratio were calculated.
(Powder X-ray diffraction measurement device specifications)
Device name: X'Pert Pro MPD manufactured by PANallytical, Netherlands
Optical system: Concentrated optical system (measurement conditions)
X-ray output (CuKα): 40 kV, 30 mA, scanning axis: θ / 2θ
Scanning range (2θ): 10.0-155.0 °

<Calculation of lattice constant, atomic coordinates, ODP, site occupancy>
The X-ray diffraction pattern was analyzed by the Rietveld analysis program Rietan-FP. A virtual group M = (1-xy) having an electron density obtained by adding R (−3) m [166] as a space group of the crystal structure model and adding (Ni, Mn, Co) as a transition metal element at a composition ratio. The sum of the occupation ratios of Ni + xMn + yCo, 3a (Li) site and 3b (M) site was 1 (Li _3a + M _3a = 1, M _3b + Li _3b = 1), respectively. The strain ODP of the oxygen octahedron centered on (Ni, Mn, Co) atoms was determined by the following equation.

Here, z _O represents the z-axis coordinate of the oxygen atom obtained by Rietveld analysis, and the deviation from 0.25 is the displacement amount of the oxygen atom. Table 3 shows the mixing ratio (%) of metal elements other than Li at the 3a site, the lattice constant, the oxygen atom coordinate z _O and the ODP value.

<Median diameter of pulverized particles in slurry>
Using a known laser diffraction / scattering particle size distribution measuring device, the refractive index was set to 1.24, and the particle diameter standard was measured as the volume standard. Further, a 0.1 wt% aqueous solution of sodium hexametaphosphate was used as a dispersion medium, and measurement was performed after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz).

<Median Diameter as Average Particle Diameter of Raw Material Li ₂ CO ₃ Powder>
Using a known laser diffraction / scattering particle size distribution measuring apparatus (LA-920, manufactured by Horiba, Ltd.), the refractive index was set to 1.24, and the particle diameter standard was measured as a volume standard. Further, ethyl alcohol was used as a dispersion medium, and measurement was performed after ultrasonic dispersion for 5 minutes (output 30 W, frequency 22.5 kHz).

<Physical properties of particulate powder obtained by spray drying>
The form was confirmed by SEM observation and cross-sectional SEM observation. The median diameter and 90% cumulative diameter (D ₉₀ ) as the average particle diameter are set to a refractive index of 1.24 using a known laser diffraction / scattering particle size distribution measuring device (LA-920, manufactured by Horiba, Ltd.) The particle diameter standard was measured using the volume standard. Further, a 0.1 wt% sodium hexametaphosphate aqueous solution was used as a dispersion medium, and measurement was performed after 0 minutes, 1 minute, 3 minutes, and 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz). The specific surface area was determined by the BET method. The bulk density was determined as the powder packing density when 4 to 10 g of the sample powder was put in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm.

[Production and evaluation of battery]
Using the lithium nickel manganese cobalt composite oxide powders produced in the following examples and comparative examples as positive electrode materials (positive electrode active materials), lithium secondary batteries were produced and evaluated by the following methods.

(1) Rate test:
What was weighed in a ratio of 75% by weight of the obtained lithium nickel manganese cobalt composite oxide powder, 20% by weight of acetylene black, and 5% by weight of polytetrafluoroethylene powder, was thoroughly mixed in a mortar and made into a thin sheet. Was punched out using a 9 mmφ punch. At this time, the total weight was adjusted to about 8 mg. This was pressure-bonded to an aluminum expanded metal to obtain a 9 mmφ positive electrode.

This 9 mmφ positive electrode is used as a test electrode, a lithium metal plate is used as a counter electrode, and LiPF ₆ is added to a solvent of EC (ethylene carbonate): DMC (dimethyl carbonate): EMC (ethyl methyl carbonate) = 3: 3: 4 (volume ratio). Using an electrolytic solution dissolved at 1 mol / L, a coin-type cell was assembled using a porous polyethylene film having a thickness of 25 μm as a separator.

The obtained coin-type cell was subjected to a constant current constant voltage charge of 0.2 mA / cm ² at an upper limit voltage of 4.2 V and a constant current discharge test of 0.2 mA / cm ² at a lower limit voltage of 3.0 V in the first cycle. In the second cycle, a constant current constant voltage charge of 0.5 mA / cm ² at an upper limit voltage of 4.2 V and a constant current discharge test of 0.2 mA / cm ² at a lower limit voltage of 3.0 V were conducted. the cycle, constant current charge of 0.5 mA / cm ^2, was constant current discharge test of 11 mA / cm ^2.
At this time, the 0.1 C discharge capacity (mAh / g) (initial discharge capacity) of the first cycle and the 0.1 C discharge capacity (mAh / g) (third discharge capacity) of the third cycle were examined.

(2) Low temperature load characteristic test and high temperature cycle test:
What was weighed in a ratio of 75% by weight of the obtained lithium nickel manganese cobalt composite oxide powder, 20% by weight of acetylene black, and 5% by weight of polytetrafluoroethylene powder was sufficiently mixed in a mortar to form a thin sheet. Punched using a 12 mmφ punch. At this time, the total weight was adjusted to about 18 mg. This was pressure-bonded to an aluminum expanded metal to obtain a 12 mmφ positive electrode.

  Using the results of charge and discharge in the first cycle in the rate test of (1), the initial charge capacity per unit weight of the positive electrode active material is Qs (C) [mAh / g], and the initial discharge capacity is Qs (D) [mAh / g].

Graphite powder having an average particle size of 8 to 10 μm (d ₀₀₂ = 3.35 Å) was used as the negative electrode active material, and polyvinylidene fluoride was used as the binder, and these were weighed at a weight ratio of 92.5: 7.5. Were mixed in an N-methylpyrrolidone solution to obtain a negative electrode mixture slurry. This slurry was applied to one side of a 20 μm thick copper foil, dried to evaporate the solvent, punched to 12 mmφ, and pressed at 0.5 ton / cm ² (49 MPa) to form a negative electrode. At this time, the amount of the negative electrode active material on the electrode was adjusted to be about 7 to 8 mg.

A test in which a negative electrode is used as a test electrode, a battery cell is assembled using lithium metal as a counter electrode, and lithium ions are occluded in the negative electrode by a constant current-constant voltage method (cut current 0.05 mA) of 0.2 mA / cm ² -3 mV. The initial occlusion capacity per unit weight of the negative electrode active material when performing at a lower limit of 0 V was defined as Q _f [mAh / g].

The positive electrode and the negative electrode were combined, a test battery was assembled using a coin cell, and the battery performance was evaluated. That is, the above-described positive electrode prepared is placed on the positive electrode can of the coin cell, a porous polyethylene film having a thickness of 25 μm is placed thereon as a separator, pressed with a polypropylene gasket, and then EC ( An electrolytic solution in which LiPF ₆ was dissolved at a rate of 1 mol / L in a solvent of ethylene carbonate): DMC (dimethyl carbonate): EMC (ethyl methyl carbonate) = 3: 3: 4 (volume ratio) was added to the can. After fully infiltrating the separator, the above-described negative electrode was placed, a negative electrode can was placed and sealed, and a coin-type lithium secondary battery was produced. At this time, the balance between the weight of the positive electrode active material and the weight of the negative electrode active material was set so as to satisfy the following expression.
Positive electrode active material weight [g] / Negative electrode active material weight [g]
= (Q _f [mAh / g] /1.2) Qs (C) [mAh / g]

In order to measure the low temperature load characteristics of the battery thus obtained, the 1 hour rate current value of the battery, that is, 1C, was set as shown in the following equation, and the following tests were performed.
1C [mA] = Qs (D) × positive electrode active material weight [g] / hour [h]

First, a constant current 0.2C charge / discharge cycle and a constant current 1C charge / discharge cycle were performed at room temperature. The upper limit of charging was 4.1 V, and the lower limit voltage was 3.0 V. Next, when a coin cell adjusted to a charging depth of 40% is held in a low temperature atmosphere of −30 ° C. for 1 hour or longer by 1/3 C constant current charging / discharging and then discharged for 10 seconds at a constant current of 0.5 C [mA]. Assuming that the voltage after 10 seconds is V [mV] and the voltage before discharge is V ₀ [mV], the low-temperature resistance value R [Ω] is calculated from the following equation as ΔV = V−V ₀ .
R [Ω] = ΔV [mV] /0.5C [mA]

Next, a constant current 0.2C charge / discharge cycle was conducted at a high temperature of 60 ° C., followed by a constant current 1C charge / discharge cycle 100. The upper limit of charging was 4.1 V, and the lower limit voltage was 3.0 V.
At this time, the ratio of the discharge capacity Qh (100) at the 100th cycle of 1C charge / discharge at 60 ° C. was calculated as the high-temperature cycle capacity retention ratio P by the following formula, and the high-temperature characteristics of the batteries were compared with this value.
P [%] = {Qh (100) / Qh (1)} × 100
Next, in the same manner as described above, the resistance value R [Ω] after this high-temperature cycle test was calculated.

  The smaller the low-temperature resistance value of the battery, the better the low-temperature load characteristics, and the higher the high-temperature cycle capacity retention rate, the better the high-temperature cycle characteristics.

[Production of Lithium Transition Metal Composite Oxide Powder (Examples and Comparative Examples)]
<Example 1>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, WO ₃ are mixed with Li: Ni: Mn: Co: W = 1.05: 0.50: 0.30: 0.20: 0. After weighing and mixing so that the molar ratio was 010, pure water was added thereto to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.30 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 15% by weight, viscosity 1290 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 7 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 6429). The drying inlet temperature was 150 ° C. Particulate powder obtained by spray drying with a spray dryer, about 15 g, was charged into an alumina crucible, fired at 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then classified ( performed 45 [mu] m), 10 ³ Omega volume resistivity of 6.7 × · cm, the carbon concentration is 0.042 wt%, the composition is _{Li (Li 0.030 Ni 0.485 Mn 0.293} Co 0.192) O ₂ lithium nickel manganese cobalt composite oxide (x = 0.302, y = 0.198, z = 0.061) was obtained. When the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 0.96 mol%. The average primary particle diameter is 0.4 μm, the median diameter is 6.0 μm, the 90% cumulative diameter (D ₉₀ ) is 9.4 μm, the bulk density is 1.5 g / cm ³ , and the BET specific surface area is 1.7 m ² / g. Further, the atomic ratio of W on the primary particle surface was 17.0 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). Further, in the particle outermost surface (Ni, Mn, Co) and the atomic ratio _{R 0} of W relative to the total of, at a depth of 10nm from the particle surface (Ni, Mn, Co) to the total atomic ratio _{R 10} of W to the sum of The ratio R ₀ / R _{10 of} was 4.5.

<Example 2>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, WO ₃ are mixed with Li: Ni: Mn: Co: W = 1.05: 0.50: 0.30: 0.20: 0. After weighing and mixing so that the molar ratio was 010, pure water was added thereto to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.32 μm using a circulating medium agitation type wet pulverizer (DM45 type).
Next, this slurry (solid content 18% by weight, viscosity 1330 cp) was spray-dried using a four-fluid nozzle type spray dryer (manufactured by Fujisaki Electric Co., Ltd .: MDP-050 type). At this time, air was used as the dry gas, the dry gas introduction amount G was 1600 L / min, and the slurry introduction amount S was 780 mL / min (gas-liquid ratio G / S = 2051). The drying inlet temperature was 200 ° C. About 500 g of particulate powder obtained by spray-drying with a spray dryer is charged into an alumina square bowl and fired at 1000 ° C. for 4.75 hours in an air atmosphere (temperature increase rate 1.85 ° C./min, temperature decrease rate: After about 3.33 ° C./min), classification (45 μm) is performed, the volume resistivity is 8.8 × 10 ³ Ω · cm, the carbon concentration is 0.054 wt%, and the composition is Li (Li _0.022). Ni _0.493 Mn _0.292 Co _0.193) lithium nickel manganese cobalt composite oxide of _{O 2 (x = 0.299, y} = 0.197, z = 0.045) was obtained. When the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 0.96 mol%. The average primary particle diameter is 0.3 μm, the median diameter is 7.1 μm, the 90% cumulative diameter (D ₉₀ ) is 11.4 μm, the bulk density is 1.6 g / cm ³ , and the BET specific surface area is 1.7 m ² / g. Further, the atomic ratio of W on the primary particle surface was 16.3 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). Further, in the particle outermost surface (Ni, Mn, Co) and the atomic ratio _{R 0} of W relative to the total of, at a depth of 10nm from the particle surface (Ni, Mn, Co) to the total atomic ratio _{R 10} of W to the sum of The ratio R ₀ / R ₁₀ was 4.4.

<Example 3>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, H ₃ BO ₃ , WO ₃ are replaced with Li: Ni: Mn: Co: B: W = 1.05: 0.50: 0.30. : Weighed and mixed so that the molar ratio was 0.20: 0.0025: 0.010, and then added pure water to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.28 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 15% by weight, viscosity 1160 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 6 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 7500). The drying inlet temperature was 150 ° C. About 15 g of particulate powder obtained by spray-drying with a spray dryer is placed in an alumina crucible, fired at 975 ° C. for 6 hours in an air atmosphere (heating rate of 3.33 ° C./min.), And then crushed. to a volume resistivity of 4.9 × 10 ⁴ Ω · cm, the carbon concentration is 0.055 wt%, the composition is _{Li (Li 0.024 Ni 0.489 Mn 0.293} Co 0.194) O 2 Of lithium nickel manganese cobalt composite oxide (x = 0.301, y = 0.199, z = 0.049) was obtained. When the total molar ratio of (Ni, Mn, Co) was 1, the molar ratios of B and W were 0.96 mol% and 0.24 mol%, respectively. The average primary particle size is 0.4 μm, the median diameter is 4.6 μm, the 90% cumulative diameter (D ₉₀ ) is 6.9 μm, the bulk density is 1.8 g / cm ³ , and the BET specific surface area is 1.7 m ² / g. Met. Further, the atomic ratio of B on the primary particle surface is 32.0 times the atomic ratio of B (boron) of the entire particle (B / (Ni + Mn + Co)), and the atomic ratio of W (tungsten) of the entire particle (W / With respect to (Ni + Mn + Co)), the atomic ratio of W on the primary particle surface was 13.5 times. Further, the atomic ratio R ₀ of B or W with respect to the sum of (Ni, Mn, Co) on the outermost surface of the particle and the sum of atoms of B or W with respect to the sum of (Ni, Mn, Co) at a depth of 10 nm from the particle surface. The ratio R ₀ / R _{10 with} respect to the ratio R ₁₀ was 3.3 for B and 4.0 for W.

<Example 4>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, WO ₃ are mixed with Li: Ni: Mn: Co: W = 1.05: 0.40: 0.40: 0.20: 0. After weighing and mixing so that the molar ratio was 010, pure water was added thereto to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.25 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 15% by weight, viscosity 980 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 6 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 7500). The drying inlet temperature was 150 ° C. About 15 g of particulate powder obtained by spray-drying with a spray dryer was placed in an alumina crucible, fired at 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then classified ( 45 μm), volume resistivity is 4.8 × 10 ⁵ Ω · cm, carbon concentration is 0.025 wt%, composition is Li (Li _0.035 Ni _0.386 Mn _0.389 Co _0.190 ) O ₂ lithium nickel manganese cobalt composite oxide (x = 0.404, y = 0.197, z = 0.073) was obtained. Further, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 0.95 mol%. The average primary particle diameter is 0.3 μm, the median diameter is 2.5 μm, the 90% cumulative diameter (D ₉₀ ) is 4.6 μm, the bulk density is 1.1 g / cm ³ , and the BET specific surface area is 2.7 m ² / g. Furthermore, the atomic ratio of W on the primary particle surface was 10.1 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). Further, in the particle outermost surface (Ni, Mn, Co) and the atomic ratio _{R 0} of W relative to the total of, at a depth of 10nm from the particle surface (Ni, Mn, Co) to the total atomic ratio _{R 10} of W to the sum of The ratio R ₀ / R ₁₀ was 4.0.

<Example 5>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, and WO ₃ are mixed with Li: Ni: Mn: Co: W = 1.05: 0.60: 0.20: 0.20: 0. After weighing and mixing so that the molar ratio was 010, pure water was added thereto to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.30 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 15% by weight, viscosity 1480 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 6.7 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 6716). The drying inlet temperature was 150 ° C. About 15 g of particulate powder obtained by spray-drying with a spray dryer was placed in an alumina crucible and fired at 850 ° C. for 6 hours in an air atmosphere (heating rate of 3.33 ° C./min.), Followed by classification ( 45 μm), volume resistivity is 5.3 × 10 ² Ω · cm, carbon concentration is 0.119 wt%, composition is Li (Li _0.028 Ni _0.587 Mn _0.193 Co _0.192 ) O ₂ lithium nickel manganese cobalt composite oxide (x = 0.199, y = 0.197, z = 0.58) was obtained. Further, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 0.95 mol%. The average primary particle diameter is 0.2 μm, the median diameter is 5.0 μm, the 90% cumulative diameter (D ₉₀ ) is 7.5 μm, the bulk density is 1.9 g / cm ³ , and the BET specific surface area is 1.6 m ² / g. Further, the atomic ratio of W on the primary particle surface was 8.6 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). Further, in the particle outermost surface (Ni, Mn, Co) and the atomic ratio _{R 0} of W relative to the total of, at a depth of 10nm from the particle surface (Ni, Mn, Co) to the total atomic ratio _{R 10} of W to the sum of The ratio R ₀ / R _{10 of} was 3.4.

<Example 6>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, Ta ₂ O ₅ are mixed with Li: Ni: Mn: Co: Ta = 1.05: 0.50: 0.30: 0.20: After weighing and mixing to a molar ratio of 0.010, pure water was added to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.29 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 15% by weight, viscosity 1670 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 7 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 6429). The drying inlet temperature was 150 ° C. About 15 g of particulate powder obtained by spray-drying with a spray dryer was placed in an alumina crucible and calcined at 900 ° C. for 6 hours in an air atmosphere (heating / cooling rate 3.33 ° C./min.), Then classified ( 45 μm), the volume resistivity is 2.5 × 10 ³ Ω · cm, the carbon concentration is 0.054% by weight, and the composition is Li (Li _0.044 Ni _0.472 Mn _0.295 Co _0.189 ). A lithium nickel manganese cobalt composite oxide (x = 0.308, y = 0.198, z = 0.091) of O ₂ was obtained. Further, when the total molar ratio of (Ni, Mn, Co) was 1, the Ta molar ratio was 0.92 mol%. The average primary particle diameter is 0.3 μm, the median diameter is 3.7 μm, the 90% cumulative diameter (D ₉₀ ) is 6.1 μm, the bulk density is 1.3 g / cm ³ , and the BET specific surface area is 2.2 m ² / g. Furthermore, the atomic ratio of Ta on the surface of the primary particles was 7.6 times the Ta (tantalum) atomic ratio of the entire particle (Ta / (Ni + Mn + Co)). Further, the atomic ratio R ₀ of Ta to the total of (Ni, Mn, Co) on the outermost surface of the particle, and the atomic ratio R ₁₀ of total Ta to the total of (Ni, Mn, Co) at a depth of 10 nm from the particle surface The ratio R ₀ / R ₁₀ was 4.3.
The specific surface area was 0.7 m ² / g.

<Example 7>
It was produced in the same manner as in Example 6 except that the firing temperature was 950 ° C., the volume resistivity was 6.1 × 10 ³ Ω · cm, the contained carbon concentration was 0.033 wt%, and the composition was Li (Li _0.046 Ni _0.473 Mn _0.293 Co _0.188) lithium nickel manganese cobalt composite oxide of _{O 2 (x = 0.307, y} = 0.197, z = 0.097) was obtained. Further, when the total molar ratio of (Ni, Mn, Co) was 1, the Ta molar ratio was 0.98 mol%. The average primary particle diameter is 0.6 μm, the median diameter is 5.0 μm, the 90% cumulative diameter (D ₉₀ ) is 7.3 μm, the bulk density is 1.4 g / cm ³ , and the BET specific surface area is 1.0 m ² / g. Further, the atomic ratio of Ta on the primary particle surface was 8.7 times the Ta (tantalum) atomic ratio of the entire particle (Ta / (Ni + Mn + Co)). Further, the atomic ratio R ₀ of Ta to the total of (Ni, Mn, Co) on the outermost surface of the particle, and the atomic ratio R ₁₀ of total Ta to the total of (Ni, Mn, Co) at a depth of 10 nm from the particle surface The ratio R ₀ / R ₁₀ was 5.1.

<Comparative Example 1>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, WO ₃ are mixed with Li: Ni: Mn: Co: W = 1.12: 0.45: 0.45: 0.10: 0. After weighing and mixing so that the molar ratio was 010, pure water was added thereto to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.23 μm using a circulating medium agitation type wet pulverizer (DM45 type).
Next, this slurry (solid content 16.5 wt%, viscosity 1650 cp) was spray-dried using a four-fluid nozzle type spray dryer (Fujisaki Electric Co., Ltd .: MDP-050 type). At this time, air was used as the dry gas, the dry gas introduction amount G was 1600 L / min, and the slurry introduction amount S was 780 mL / min (gas-liquid ratio G / S = 2051). The drying inlet temperature was 200 ° C. About 370 g of particulate powder obtained by spray drying with a spray dryer is charged into an alumina square bowl and fired at 1000 ° C. for 2 hours in an air atmosphere (temperature increase rate 1.7 ° C./min, temperature decrease rate: about 3 3 ° C./min), and then classified using a Puffer footer (manufactured by Tsukasa Kogyo Co., Ltd.) with a 45 μm mesh, the volume resistivity is 6.3 × 10 ⁴ Ω · cm, and the carbon concentration is 0.031 wt% , composition _{Li (Li 0.053 Ni 0.425 Mn 0.427} Co 0.095) lithium nickel manganese cobalt composite oxide of _{O 2 (x = 0.451, y} = 0.100, z = 0.111 ) Further, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 1.01 mol%. The average primary particle diameter is 0.2 μm, the median diameter is 2.7 μm, the 90% cumulative diameter (D ₉₀ ) is 4.9 μm, the bulk density is 1.0 g / cm ³ , and the BET specific surface area is 2.8 m ² / g. Further, the atomic ratio of W on the primary particle surface was 7.8 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). Further, in the particle outermost surface (Ni, Mn, Co) and the atomic ratio _{R 0} of W relative to the total of, at a depth of 10nm from the particle surface (Ni, Mn, Co) to the total atomic ratio _{R 10} of W to the sum of The ratio R ₀ / R _{10 of} was 4.5.

<Comparative Example 2>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH are weighed so as to have a molar ratio of Li: Ni: Mn: Co = 1.05: 0.50: 0.30: 0.20 After mixing, pure water was added to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.26 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 15% by weight, viscosity 1690 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 7.0 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 6429). The drying inlet temperature was 150 ° C. About 15 g of particulate powder obtained by spray-drying with a spray dryer was placed in an alumina crucible, fired at 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then classified ( performed 45 [mu] m), 10 ³ Omega volume resistivity of 1.0 × · cm, the carbon concentration is 0.024 wt%, the composition is _{Li (Li 0.033 Ni 0.483 Mn 0.293} Co 0.191) O ₂ lithium nickel manganese cobalt composite oxide (x = 0.303, y = 0.198, z = 0.068) was obtained. The average primary particle diameter is 5.1 μm, the median diameter is 8.9 μm, the 90% cumulative diameter (D ₉₀ ) is 13.5 μm, the bulk density is 2.7 g / cm ³ , and the BET specific surface area is 0.7 m ² / g.

<Comparative Example 3>
It was produced in the same manner as in Example 1 except that the firing temperature was 850 ° C., the volume resistivity was 1.3 × 10 ³ Ω · cm, the carbon concentration was 0.088 wt%, and the composition was Li (Li _0.043 Ni _0.472 Mn _0.294 Co _0.191) lithium nickel manganese cobalt composite oxide of _{O 2 (x = 0.307, y} = 0.199, to obtain a z = 0.091). Further, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 0.94 mol%. The average primary particle diameter is 0.2 μm, the median diameter is 3.9 μm, the 90% cumulative diameter (D ₉₀ ) is 6.4 μm, the bulk density is 1.4 g / cm ³ , and the BET specific surface area is 4.0 m ² / g. Furthermore, the atomic ratio of W on the primary particle surface was 6.1 times the atomic ratio of W (tungsten) for the entire particle (W / (Ni + Mn + Co)). Further, in the particle outermost surface (Ni, Mn, Co) and the atomic ratio _{R 0} of W relative to the total of, at a depth of 10nm from the particle surface (Ni, Mn, Co) to the total atomic ratio _{R 10} of W to the sum of The ratio R ₀ / R _{10 of} was 3.2.

<Comparative example 4>
Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , and CoOOH are weighed so as to have a molar ratio of Li: Ni: Mn: Co = 1.05: 0.40: 0.40: 0.20 After mixing, pure water was added to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.27 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 15% by weight, viscosity 1260 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 6.7 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 6716). The drying inlet temperature was 150 ° C. About 15 g of particulate powder obtained by spray-drying with a spray dryer was placed in an alumina crucible, fired at 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then classified ( 45 μm), volume resistivity is 5.1 × 10 ⁴ Ω · cm, carbon concentration is 0.027 wt%, and composition is Li (Li _0.037 Ni _0.384 Mn _0.389 Co _0.190 ) A lithium nickel manganese cobalt composite oxide (x = 0.404, y = 0.197, z = 0.076) of O ₂ was obtained. The average primary particle diameter is 0.6 μm, the median diameter is 4.2 μm, the 90% cumulative diameter (D ₉₀ ) is 6.5 μm, the bulk density is 1.3 g / cm ³ , and the BET specific surface area is 2.7 m ² / g.

<Comparative Example 5>
Weigh Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , and CoOOH so that the molar ratio is Li: Ni: Mn: Co = 1.05: 0.60: 0.20: 0.20. After mixing, pure water was added to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.29 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 14% by weight, viscosity 1610 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 6.7 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 6716). The drying inlet temperature was 150 ° C. About 15 g of particulate powder obtained by spray-drying with a spray dryer was placed in an alumina crucible and calcined at 900 ° C. for 6 hours in an air atmosphere (heating / cooling rate 3.33 ° C./min.), Then classified ( 45 μm), the volume resistivity is 2.7 × 10 ³ Ω · cm, the carbon concentration is 0.270 wt%, and the composition is Li (Li _0.038 Ni _0.577 Mn _0.194 Co _0.191 ) O ₂ lithium nickel manganese cobalt composite oxide (x = 0.202, y = 0.198, z = 0.078) was obtained. The average primary particle diameter is 1.5 μm, the median diameter is 4.0 μm, the 90% cumulative diameter (D ₉₀ ) is 12.9 μm, the bulk density is 2.6 g / cm ³ , and the BET specific surface area is 1.4 m ² / g.

  The compositions and physical property values of the lithium nickel manganese cobalt based composite oxide powders produced in Examples 1 to 7 and Comparative Examples 1 to 5 are shown in Tables 1 to 7. Table 8 shows the powder properties of the spray-dried body, which is a firing precursor.

  Moreover, the concentration distribution curve (XPS analysis) of the depth direction from the surface of the additive element in the lithium nickel manganese cobalt complex oxide manufactured in Examples 1-7 and Comparative Examples 1 and 3 is shown in FIGS. The SERS patterns of the lithium nickel manganese cobalt composite oxide powders produced in Examples 1-7 and Comparative Examples 1-5 are shown in FIGS. 10-21, and the pore distribution curves are shown in FIGS. SEM images (photographs) (magnification × 10,000) are shown in FIGS. 34 to 45, respectively, and powder X-ray diffraction patterns are shown in FIGS. 46 to 57, respectively.

<Production and evaluation of battery>
Using the lithium nickel manganese cobalt composite oxide powders produced in Examples 1 to 7 and Comparative Examples 1 to 5 as positive electrode materials (positive electrode active materials), lithium secondary batteries were produced and evaluated by the method described above. The results are shown in Table 9.

In addition, (1) as an acceptance criterion of the example in the rate test, the initial discharge capacity in the first cycle is set to 150 mAh / g or more, and the high rate discharge capacity at 11 mA / cm ² in the third cycle is set to 115 mAh / g or more. did. Moreover, (2) Low temperature load characteristic test and high temperature cycle test Examples of acceptance criteria of the low temperature resistance value before the cycle is 350Ω or less, the low temperature resistance value after the cycle is 550Ω or less, and the 60 ° C. cycle maintenance rate is 85% or more. Was set to be.

  From Table 9, it can be seen that according to the lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material of the present invention, a lithium secondary battery excellent in load characteristics can be realized.

  The use of the lithium secondary battery of the present invention is not particularly limited, and can be used for various known uses. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, and transceivers. Electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, lighting equipment, toys, game machines, watches, strobes, cameras, automobile power sources, and the like.

In Example 1, it is a graph which shows W density | concentration distribution to the depth direction from the particle | grain surface of the manufactured lithium nickel manganese cobalt complex oxide. In Example 2, it is a graph which shows W density | concentration distribution to the depth direction from the particle | grain surface of the manufactured lithium nickel manganese cobalt complex oxide. In Example 3, it is a graph which shows B and W density | concentration distribution from the particle | grain surface of the lithium nickel manganese cobalt complex oxide manufactured to the depth direction. In Example 4, it is a graph which shows W density | concentration distribution to the depth direction from the particle | grain surface of the manufactured lithium nickel manganese cobalt complex oxide. In Example 5, it is a graph which shows W density | concentration distribution to the depth direction from the particle | grain surface of the manufactured lithium nickel manganese cobalt complex oxide. In Example 6, it is a graph which shows Ta concentration distribution to the depth direction from the particle | grain surface of the manufactured lithium nickel manganese cobalt complex oxide. In Example 7, it is a graph which shows Ta concentration distribution to the depth direction from the particle | grain surface of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative Example 1, it is a graph showing the W concentration distribution in the depth direction from the particle surface of the manufactured lithium nickel manganese cobalt composite oxide. In the comparative example 3, it is a graph which shows W concentration distribution from the particle | grain surface of the lithium nickel manganese cobalt complex oxide manufactured to the depth direction. In Example 1, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 2, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 3, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 4, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 5, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 6, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 7, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Comparative example 1, it is a graph which shows the SERS pattern of the manufactured lithium nickel manganese cobalt complex oxide. In the comparative example 2, it is a graph which shows the SERS pattern of the manufactured lithium nickel manganese cobalt complex oxide. In the comparative example 3, it is a graph which shows the SERS pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Comparative Example 4, it is a graph which shows the SERS pattern of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 5, it is a graph which shows the SERS pattern of the manufactured lithium nickel manganese cobalt complex oxide. In Example 1, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Example 2, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Example 3, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Example 4, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Example 5, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Example 6, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Example 7, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Comparative example 1, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Comparative example 2, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Comparative example 3, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Comparative example 4, it is a graph which shows the pore distribution curve of the lithium nickel manganese cobalt complex oxide powder manufactured. In Comparative Example 5, it is a graph showing a pore distribution curve of the manufactured lithium nickel manganese cobalt composite oxide powder. In Example 1, it is a SEM image (photograph) (acceleration voltage 3kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Example 2, it is a SEM image (photograph) (acceleration voltage 3kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Example 3, it is a SEM image (photograph) (acceleration voltage 15 kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Example 4, it is a SEM image (photograph) (acceleration voltage 3 kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Example 5, it is a SEM image (photograph) (acceleration voltage 3 kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Example 6, it is a SEM image (photograph) (acceleration voltage 3kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Example 7, it is a SEM image (photograph) (acceleration voltage 3 kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 1, it is a SEM image (photograph) (acceleration voltage 15kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 2, it is a SEM image (photograph) (acceleration voltage 3kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 3, it is a SEM image (photograph) (acceleration voltage 3kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 4, it is a SEM image (photograph) (acceleration voltage 3kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 5, it is a SEM image (photograph) (acceleration voltage 15kV, magnification x10,000) of the manufactured lithium nickel manganese cobalt complex oxide. In Example 1, it is a graph which shows the XRD pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 2, it is a graph which shows the XRD pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 3, it is a graph which shows the XRD pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 4, it is a graph which shows the XRD pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 5, it is a graph which shows the XRD pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 6, it is a graph which shows the XRD pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Example 7, it is a graph which shows the XRD pattern of the lithium nickel manganese cobalt complex oxide manufactured. In Comparative example 1, it is a graph which shows the XRD pattern of the manufactured lithium nickel manganese cobalt complex oxide. In the comparative example 2, it is a graph which shows the XRD pattern of the manufactured lithium nickel manganese cobalt complex oxide. In the comparative example 3, it is a graph which shows the XRD pattern of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 4, it is a graph which shows the XRD pattern of the manufactured lithium nickel manganese cobalt complex oxide. In Comparative example 5, it is a graph which shows the XRD pattern of the manufactured lithium nickel manganese cobalt complex oxide.

Claims (27)

The composition is represented by the following formula (I), and at least one element selected from Mo, W, Nb, Ta and Re is based on the total molar amount of Mn, Ni and Co in formula (I). The lithium transition metal compound powder for a lithium secondary battery positive electrode material, characterized by being contained in a proportion of 0.1 mol% or more and 5 mol% or less.
[L] _3a [M] _3b [O ₂ ] _6c (I)
(However, in the above formula (I), L is an element containing at least Li, and M is an element containing at least Ni, Mn and Co, or Li, Ni, Mn and Co,
0.4 ≦ Ni / (Mn + Ni + Co) molar ratio <0.7
0.1 <Mn / (Mn + Ni + Co) molar ratio ≦ 0.4
0.1 ≦ Co / (Mn + Ni + Co) molar ratio ≦ 0.3
And the molar ratio of Li in M is 0 or more and 0.05 or less.
The subscript next to [] represents a site in the crystal structure, the 3a site being the Li site, the 3b site being the transition metal site, and the 6c site being the oxygen site. ) M in said Formula (I) is represented by following formula (II), The lithium transition metal type compound powder for lithium secondary battery positive electrode materials of Claim 1 characterized by the above-mentioned.
M = Li _{z / (2 + z)} (Ni _1-xy Mn _x Co _y ) _{2 / (2 + z)} (II)
(However, in the above formula (II),
0.1 <x ≦ 0.4
0.15 ≦ y ≦ 0.25
0.001 ≦ z ≦ 0.1
It is. )   In powder X-ray diffraction measurement using CuKα rays, when the half-value width derived from the CuKα1 rays of the (110) diffraction peak having a diffraction angle 2θ of around 64.5 to 65 ° is FWHM (110), 0 The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 1, wherein the powder is represented by .01 ≦ FWHM (110) ≦ 0.3. In the powder X-ray diffraction measurement using CuKα ray, the diffraction angle 2θ is (018) diffraction peak existing in the vicinity of 64 to 64.5 °, (110) diffraction peak existing in the vicinity of 64.5 to 65 °, and 68 In the (113) diffraction peak existing around ˜68.5 °, when there is no diffraction peak derived from a different phase or a diffraction peak derived from a different phase on the higher angle side of each peak top, the original crystal phase 4. The lithium transition metal-based compound for a lithium secondary battery positive electrode material according to claim 1, wherein the integrated intensity ratio of the heterophasic peak to the diffraction peak is in the following range, respectively. powder.
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.10
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.15
0 ≦ I ₁₁₃ ^* / I ₁₁₃ ≦ 0.30
(Here, I ₀₁₈ , I ₁₁₀ , and I ₁₁₃ represent the integrated intensities of the diffraction peaks, respectively (018), (110), and (113), and I ₀₁₈ ^* , I ₁₁₀ ^* , and I ₁₁₃ ^* are (018 ), (110), (113) represents the integrated intensity of a diffraction peak derived from a different phase appearing at a higher angle than the peak top of the diffraction peak.)   The primary particles of the lithium transition metal compound powder are aggregated to form secondary particles, and the ratio A / B between the median diameter A and the average diameter (average primary particle diameter B) of the secondary particles is 8 to 100. 5. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 1, wherein the powder is in the range of   The atomic ratio of the total of Mo, W, Nb, Ta, and Re to the total of Li and metal elements other than Mo, W, Nb, Ta, and Re in the surface portion of the primary particle is five times the atomic ratio of the entire primary particle. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 5, which is as described above. The atomic ratio R ₀ of the total of Mo, W, Nb, Ta and Re to the total of Li and the metal elements other than Mo, W, Nb, Ta and Re on the outermost surface of the primary particle, and Li at a depth of 10 nm from the surface of the primary particle And the ratio R ₀ / R ₁₀ of the total atomic ratio R ₁₀ of the metal elements to the total of metal elements other than the metal elements is 3 times or more, 7. The lithium transition metal type compound powder for a lithium secondary battery positive electrode material described in the item.   It has a continuous composition gradient structure in which at least one element selected from Mo, W, Nb, Ta and Re exists with a non-linear concentration gradient in the depth direction from the primary particle surface. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 7.   9. The lithium secondary battery positive electrode material according to claim 1, wherein a mixing ratio of a metal element other than Li to the 3a site in the formula (I) is 6% or less. Lithium transition metal compound powder. In the infrared absorption spectrum, comprising: the peak appeared in the vicinity 560～610Cm ^-1, the difference between the peaks appearing in the vicinity of 515～540Cm ^-1 is, 40 cm ^-1 or more, the coupling structure comprising a 80 cm ^-1 or less The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 9. In surface-enhanced Raman spectrum, 530 cm ^-1 or more, of claims 1 to lithium secondary battery positive electrode material for a lithium transition metal-based according to any one of 10 and having a peak A to 630 cm ^-1 or less Compound powder. 12. The lithium according to claim 1, wherein the volume resistivity when consolidated at a pressure of 40 MPa is 1 × 10 ¹ Ω · cm or more and 5 × 10 ⁶ Ω · cm or less. Lithium transition metal compound powder for secondary battery positive electrode material.   The lithium according to any one of claims 1 to 12, wherein the C value is 0.005% or more and 0.25% by weight or less when the carbon content is C value (wt%). Lithium transition metal compound powder for secondary battery positive electrode material.   The median diameter measured after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz) using a laser diffraction / scattering particle size distribution analyzer with a refractive index of 1.24 and a particle size standard as a volume standard. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 13, wherein is 1 to 20 µm.   15. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 1, wherein the average diameter of the primary particles is 0.1 μm or more and 1 μm or less. 16. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to claim 1, wherein the BET specific surface area is 0.5 m ² / g or more and 3 m ² / g. . 2. The mercury intrusion curve according to the mercury intrusion method has a mercury intrusion amount of 0.4 cm ³ / g or more and 1.2 cm ³ / g or less when the pressure is increased from 3.86 kPa to 413 MPa. The lithium transition metal compound powder for a lithium secondary battery positive electrode material as described in any one of 1 to 16.   The pore distribution curve by the mercury intrusion method has at least one main peak having a peak top at a pore radius of 400 nm or more and 1500 nm or less, and has a peak top at a pore radius of 80 nm or more and less than 400 nm. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 17, wherein the powder has a sub-peak. In the pore distribution curve by the mercury intrusion method, the pore volume related to the main peak having a peak top at a pore radius of 400 nm or more and 1500 nm or less is 0.2 cm ³ / g or more and 0.8 cm ³ / g or less, The pore volume according to a sub-peak in which a peak top exists at a pore radius of 80 nm or more and less than 400 nm is 0.01 cm ³ / g or more and 0.2 cm ³ / g or less. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of the above. 20. The lithium transition metal compound for a lithium secondary battery positive electrode material according to claim 1, wherein the bulk density is 1.0 g / cm ³ or more and 2.5 g / cm ³ or less. powder.   Lithium carbonate is used as the lithium raw material, and in an oxygen-containing gas atmosphere, the firing temperature is 1150-500 (1-xy) (where x and y are the same as x and y in the formula (II)). 21) represents 0.1 ≦ x ≦ 0.4 and 0.15 ≦ y ≦ 0.25.) It is fired at a temperature equal to or higher than ° C. 21. The lithium transition metal type compound powder for lithium secondary battery positive electrode materials as described.   Lithium carbonate, Ni compound, Mn compound, Co compound, and metal compound containing at least one element selected from Mo, W, Nb, Ta and Re are pulverized in a liquid medium, and these are uniformly distributed The lithium secondary battery positive electrode according to any one of claims 1 to 21, comprising a spray drying step of spray drying the dispersed slurry and a firing step of firing the obtained spray dried body. Method for producing lithium transition metal compound powder for material.   In the slurry adjustment step, in a liquid medium, a laser diffraction / scattering particle size distribution measuring device is used to set the refractive index to 1.24, the particle size reference is the volume reference, and the ultrasonic dispersion for 5 minutes (output 30 W, frequency 22.5 kHz) After pulverizing until the median diameter measured becomes 0.5 μm or less, in the spray drying process, the slurry viscosity during spray drying is V (cp), the slurry supply amount is S (L / min), and the gas supply 23. The lithium secondary battery positive electrode material according to claim 22, wherein spray drying is performed under the conditions of 50 cp ≦ V ≦ 4000 cp and 500 ≦ G / S ≦ 10000 when the amount is G (L / min). For producing lithium transition metal-based compound powders for use in medical applications. Lithium carbonate, Ni compound, Mn compound, Co compound, and metal compound containing at least one element selected from Mo, W, Nb, Ta and Re are pulverized in a liquid medium, and these are uniformly distributed A spray-dried product that is obtained by spray-drying the dispersed slurry and serves as a precursor of a lithium transition metal compound powder for a positive electrode material for a lithium secondary battery, and is refracted by a laser diffraction / scattering particle size distribution analyzer. The rate is set at 1.24, the particle size standard is the volume standard, and the ultrasonic dispersion for 5 minutes with respect to the median diameter D ₅₀ [US0] measured without applying ultrasonic dispersion (output 30 W, frequency 22.5 kHz) after the measured ratio of the median diameter _{D 50 [US5], D 50} [US5] / D 50 [US0] is 0.03 or more, spray-dried product, characterized in that is 0.7 or less The spray-dried product according to claim 24, wherein the BET specific surface area is 10 m ² / g or more and 100 m ² / g or less.   It has the positive electrode active material layer containing the lithium transition metal type compound powder for lithium secondary battery positive electrode materials and binder as described in any one of Claims 1 thru | or 21 on a collector, A positive electrode for a lithium secondary battery.   27. A lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a non-aqueous electrolyte containing a lithium salt, and a positive electrode capable of inserting and extracting lithium, wherein the lithium secondary battery according to claim 26 is used as the positive electrode. A lithium secondary battery using a positive electrode for a battery.

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