JP4591717B2 - Lithium nickel manganese cobalt based composite oxide powder for lithium secondary battery positive electrode material, method for producing the same, spray-dried powder, positive electrode for lithium secondary battery and lithium secondary battery using the same - Google Patents

Description

  The present invention relates to a lithium nickel manganese cobalt composite oxide powder used as a positive electrode material for a lithium secondary battery, a production method thereof, a spray-dried powder as a precursor thereof, and the lithium nickel manganese cobalt composite oxide powder. The present invention relates to a positive electrode for a lithium secondary battery using the body, and a lithium secondary battery including the positive electrode for a lithium secondary 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. Especially for electric vehicle applications, lithium secondary batteries are required to have low cost, long life (especially life under high temperatures), excellent safety and load characteristics, and improvements 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 having a good performance balance that is low in cost, excellent in 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 such circumstances, lithium nickel manganese cobalt-based composite oxides with a layered structure have been proposed as promising candidates for active material materials that can overcome or reduce the shortcomings of these positive electrode active material materials and are excellent in battery performance balance. Has been. Particularly, in recent years, demands for lowering costs, higher voltages, and increasing safety demands are promising as positive electrode active material materials that can meet any of the demands.

  However, the degree of cost reduction, higher voltage, and safety will vary depending on the composition ratio. Therefore, for further cost reduction, use with a higher upper limit voltage, and higher safety requirements. Therefore, it is necessary to select and use one having a limited composition range, such as setting the manganese / nickel atomic ratio to 1 or more, or reducing the cobalt ratio. However, a lithium secondary battery using a lithium nickel manganese cobalt based composite oxide having such a composition range as a positive electrode material has reduced load characteristics such as rate and output characteristics. It was necessary.

  Conventionally, as for the lithium nickel manganese cobalt based composite oxide having a composition range in which the manganese / nickel atomic ratio is close to 1 and the cobalt ratio is reduced to a value specified by the present invention or less, Patent Documents 1 to 25 and Non-Patent Documents 1 to 33.

However, Patent Document 1 discloses a general formula Li [Li _x Co _y A _1-xy ] O ₂ (wherein A represents [Mn _z Ni _1-z ], and x is 0.00 to 0.00). 16 represents a numerical value in the range, y represents a numerical value in the range of 0.1 to 0.30, z represents a numerical value in the range of 0.40 to 0.65, and Lix represents the transition metal layer of the structure. A single-phase cathode material represented by) is disclosed, and it is described that a cathode material having excellent electrochemical properties can be obtained by making the cobalt doping more than about 10% of the total transition metals. However, the cathode material having a composition in which the cobalt doping amount is less than the specified ratio has a problem that it is difficult to obtain excellent electrochemical characteristics. Further, when the composition region defined in Patent Document 1 is examined in detail, the lower limit value of the molar ratio (y) of cobalt is 0.1 regardless of the amount of lithium (x) contained in the transition metal layer. In the composition region defined by the present invention (composition formula (I)), when the amount of lithium (z / (2 + z)) contained in the transition metal layer exceeds 0, the molar ratio of cobalt becomes less than 10%. The composition range of the invention was not satisfied.

  According to Patent Documents 2 to 25 and Non-Patent Documents 1 to 33, there is no description focusing on the specific half-value width of the active material crystal in the composition region defined by the present invention, and the specific diffraction peak There is no description that captures the presence or absence of a heterophasic peak that appears at a higher angle than the peak top. Furthermore, there is no description regarding particle pore control, which is a more preferable requirement, and the requirements for improving battery performance in the present invention are not satisfied. It is extremely difficult to improve.

Patent Document 26 discloses _a composition formula Li _a Mn _0.5-x Ni _0.5-y M _{x + y} O ₂ (where 0 <a <1.3, −0.1 ≦ x−y ≦ 0.1, M The total pore volume of the positive electrode active material containing the composite oxide represented by is an element other than Li, Mn, and Ni) is 0.001 ml / g or more and 0.006 ml / g or less, and uses CuKα rays. The relative intensity ratio of the diffraction peak at 2θ: 44.1 ± 1 ° to the diffraction peak at 2θ: 18.6 ± 1 ° in the powder X-ray diffraction diagram is 0.65 to 1.05, and the 2θ: The half width of the diffraction peak at 18.6 ± 1 ° is 0.05 ° or more and 0.20 ° or less, and the half width of the diffraction peak at 2θ: 44.1 ± 1 ° is 0.10 ° or more and 0.20. It is disclosed that it has a high energy density. It is described as capable of excellent in charge-discharge cycle performance. That is, according to Patent Document 26, in the composition region defined by the present invention, a description focusing on the specific half-value width of the active material crystal and a description regarding particle pore control, which is a more preferable requirement, are recognized.

  Furthermore, according to Patent Document 27 and Patent Document 28, there is no description focusing on the specific half-value width of the active material crystal in the composition region defined by the present invention, and a higher angle than the peak top of the specific diffraction peak. Although there is no description referring to the presence or absence of a heterophasic peak appearing on the side, a description regarding particle pore control, which is a more preferable requirement, is recognized. Patent Document 27 discloses a positive electrode active material for a lithium secondary battery containing a Li—Mn—Ni composite oxide containing at least lithium, manganese and nickel as constituent elements, wherein the Li—Mn—Ni composite oxide is used. Is disclosed that the total pore volume is 0.0015 ml / g or more, and that it has a high discharge capacity and excellent cycle performance.

  However, the Li—Mn—Ni based composite oxide having an atomic ratio of Ni / Mn = 1/1 described in Patent Document 26 is useful for determining whether or not to exhibit higher performance. No mention is made regarding the half width of the (110) diffraction peak, and the value of the total pore volume is extremely small compared to the value defined in the present invention, and the load characteristics are still insufficient. There was a problem. In addition, the Li-Mn-Ni composite oxide described in Patent Document 27 defines a larger pore volume value than that of Patent Document 26. The value of the pore volume is extremely small as compared with the value specified in the present invention, and there is still a problem that the load characteristics are not sufficient.

  On the other hand, Patent Document 28 discloses lithium composite oxide particles whose mercury intrusion amount is not more than a predetermined upper limit value under a specific high pressure load condition in the measurement by the mercury intrusion method, and the mercury intrusion described above. A sub-peak whose amount is equal to or greater than a predetermined lower limit or whose average pore radius is within a predetermined range, and in which the peak top exists in a specific pore radius region in addition to the conventional main peak in the pore distribution curve When the lithium composite oxide particles having a lithium secondary oxide particle are used as a positive electrode material for a lithium secondary battery, the low temperature load characteristics of the lithium secondary battery can be improved, and the coating property at the time of producing the positive electrode is excellent and suitable. It is described that it can be a positive electrode material for a lithium secondary battery.

However, in the lithium composite oxide particles described in Patent Document 28, although a composition having a relatively large cobalt ratio shows an improvement effect, the load characteristic is still insufficient for the composition range defined by the present invention. was there.
Japanese Patent No. 3571671 Japanese Patent Laid-Open No. 11-307094 JP 2000-133262 A WO2002-040404 WO2002-073718 JP 2002-145623 A WO2003-044881 WO2003-048882 JP 2003-031219 A JP 2003-081639 A JP 2003-178756 A JP 2003-203633 A JP 2003-221236 A JP 2003-238165 A JP 2003-297354 A JP 2004-031091 A Japanese Patent Application Laid-Open No. 2004-139853 JP 2004-265849 A JP 2004-281253 A JP 2004-31427 A Special table 2004-528691 JP-A-2005-150057 JP-A-2005-150093 JP 2005-150102 A JP 2005-187282 A WO2002-086993 JP 2003-051308 A JP-A-2005-123179 J. Electrochem. Soc., 149 (2002) A1332. J. Electrochem. Soc., 150 (2003) A1299. J. Power sources, 112 (2002) 41. J. Power sources, 119-121 (2003) 150. J. Electrochem. Soc., 152 (2005) A746. J. Electrochem. Soc., 151 (2004) A504. Electrochemistry, 71 (2003) 1214. Electrochim. Acta, 50 (2004) 427. J. Electrochem. Soc., 152 (2005) A566. Trans. Nonferrous Met. Soc. China, 15 (2005) 1185. J. Power sources, 146 (2005) 626. Solid State Ionics, 176 (2005) 2577. Chem. Lett., (2001) 744. Electrochem. Solid-State Lett., 5 (2002) A145. Electrochem. Solid-State Lett., 5 (2002) A263. J. Power sources, 119-121 (2003) 156. J. Power sources, 124 (2003) 170. Electrochim. Acta, 48 (2003) 1505. Electrochim. Acta, 48 (2003) 2589. Electrochim. Acta, 49 (2004) 803. Electrochem. Solid-State Lett., 7 (2004) A155. Electrochim. Acta, 49 (2004) 1565. J. Power sources, 135 (2004) 262. Electrochim. Acta, 50 (2004) 449. J. Electrochem. Soc., 151 (2004) A246. J. Power sources, 146 (2005) 650. Electrochim. Acta, 50 (2005) 5349. J. Power sources, 146 (2005) 645. Electrochem. Solid-State Lett., 8 (2005) A637. Mater. Lett., 59 (2005) 2693. Chem. Mater., 18 (2006) 1658. J. Mater. Chem., 16 (2006) 359. J. Appl. Phys., 99 (2006) 06371.

  That is, the object of the present invention is to improve load characteristics such as rate and output characteristics when used as a positive electrode material for a lithium secondary battery, and more preferably to reduce costs, increase voltage resistance, and increase safety. Lithium nickel manganese cobalt composite oxide powder for lithium secondary battery positive electrode material that can be compatible, a manufacturing method thereof, a positive electrode for lithium secondary battery using the lithium nickel manganese cobalt composite oxide powder, and It is providing the lithium secondary battery provided with the positive electrode for lithium secondary batteries.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have controlled the half-value width of a specific diffraction peak in powder X-ray diffraction measurement in a lithium nickel manganese cobalt-based composite oxide and set the composition in a specific region. Lithium nickel manganese cobalt-based composite that can achieve both low cost, high voltage resistance, high safety, load characteristics such as rate and output characteristics, etc. The inventors have found that an oxide powder can be obtained, and have completed the present invention.

That is, the lithium nickel manganese cobalt composite oxide powder for a lithium secondary battery positive electrode material of the present invention is composed of a compound represented by the following composition formula (I), and includes a crystal structure belonging to a layered structure. In powder X-ray diffraction measurement using CuKα rays, 0.01 ≦ FWHM (110) when the half-value width of the (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° is FWHM (110). ) is represented by ≦ 0.2, the value of the volume resistivity when compacted at a pressure of 40MPa is, 1 × 10 ³ Ω · cm or more and less der Rukoto 1 × 10 ⁶ Ω · cm ( Claim 1).
Li [Li _{z / (2 + z)} {(Ni _{(1 + y) / 2} Mn _{(1-y) / 2} ) _1-x Co _x } _{2 / (2 + z)} ] O ₂ (I)
(However, in the composition formula (I),
0 ≦ x ≦ 0.1
−0.1 ≦ y ≦ 0.1
(1-x) (0.05-0.98y) ≤z≤ (1-x) (0.15-0.88y)
It is. )

  Furthermore, in the composition formula (I), x, y, and z values are 0.04 ≦ x ≦ 0.099, −0.03 ≦ y ≦ 0.03, (1-x) (0.08-0), respectively. .98y) ≦ z ≦ (1-x) (0.13-0.88y) (Claim 2).

Also, in powder X-ray diffraction measurement using CuKα rays, a diffraction angle 2θ is present at a diffraction peak of around (°) 64 °, a (110) diffraction peak of around 64.5 °, and a peak of 68 °. (113) In the case where the diffraction peak does not have a diffraction peak derived from a different phase or has a diffraction peak derived from a different phase at a higher angle side than each peak top, the integration of the different phase peak with respect to the diffraction peak of the original crystal phase The intensity ratios are preferably in the following ranges, respectively.
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.20
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25
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.)

In addition, the lithium nickel manganese cobalt based composite oxide powder of the present invention has a mercury intrusion amount of 0.7 cm ³ / g or more at a pressure increase of 3.86 kPa to 413 MPa in a mercury intrusion curve by a mercury intrusion method. It is preferably 1.5 cm ³ / g or less (claim 4).

  In addition, the lithium nickel manganese cobalt based composite oxide powder of the present invention has a main distribution peak having a peak top in a pore radius of 300 nm or more and 1000 nm or less, according to a mercury intrusion method, and pores. It is preferable not to have a sub-peak having a peak top at a radius of 80 nm or more and less than 300 nm.

Further, the lithium nickel manganese cobalt based composite oxide powder of the present invention has a pore volume of 0 corresponding to the main peak having a peak top at a pore radius of 300 nm or more and 1000 nm or less in a pore distribution curve by a mercury intrusion method. .5cm ³ / g or more, preferably 1.0 cm ³ / g or less (claim 6).

  In addition, the lithium nickel manganese cobalt based composite oxide powder of the present invention is set to a refractive index of 1.24 using a laser diffraction / scattering type particle size distribution measuring apparatus, and the particle size standard is a volume standard, and it exceeds 5 minutes. The median diameter measured after sonic dispersion (output 30 W, frequency 22.5 kHz) is preferably 1 μm or more and 5 μm or less (Claim 7).

The lithium nickel manganese cobalt based composite oxide powder of the present invention preferably has a bulk density of 0.5 to 1.5 g / cm ³ (claim 8).

The lithium nickel manganese cobalt based composite oxide powder of the present invention preferably has a BET specific surface area of 1.5 to 3 m ² / g (claim 9).

  In addition, the lithium nickel manganese cobalt based composite oxide powder of the present invention has a C value of 0.005 wt% or more and 0.05 wt% or less when the carbon content is C (wt%). (Claim 10).

The lithium nickel manganese cobalt based composite oxide powder of the present invention preferably has a volume resistivity of 1 × 10 ³ Ω · cm or more and 1 × 10 ⁶ Ω · cm or less when consolidated at a pressure of 40 MPa ( Claim 11).

  The method for producing a lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material of the present invention produces such a lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material of the present invention. A slurry preparation step of obtaining a slurry in which a lithium compound, a nickel compound, a manganese compound, and a cobalt compound are pulverized in a liquid medium and uniformly dispersed, and the obtained slurry is spray-dried. A spray drying step and a firing step of firing the obtained spray-dried body in an oxygen-containing gas atmosphere at a temperature T (° C.) of 940 ° C. ≦ T ≦ 1200 ° C. (Claim 12) .

  In the method for producing a lithium nickel manganese cobalt based composite oxide powder of the present invention, the lithium compound is preferably lithium carbonate.

In the method for producing a lithium nickel manganese cobalt based composite oxide powder for a positive electrode material of a lithium secondary battery according to the present invention, in the slurry preparation step, a lithium compound, a nickel compound, a manganese compound, and a cobalt compound are mixed with a laser in a liquid medium. Using a diffraction / scattering particle size distribution measuring apparatus, the refractive index is set to 1.24, the particle diameter reference is the volume reference, and the median diameter measured after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz) is 0. When the slurry viscosity is V (cp), the slurry supply amount is S (L / min), and the gas supply amount is G (L / min) in the spray drying process. It is preferable to perform spray drying under the conditions of 50 cp ≦ V ≦ 4000 cp, 1500 ≦ G / S ≦ 5000.

The positive electrode for a lithium secondary battery of the present invention has a positive electrode active material layer containing such a lithium nickel manganese cobalt-based composite oxide powder for a lithium secondary battery positive electrode material of the present invention and a binder as a current collector. (Claim 15 ).

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 of the present invention is used (claim 16 ).

The lithium secondary battery of the present invention is preferably designed so that the charging potential of the positive electrode in a fully charged state is 4.35 V (vs. Li / Li ⁺ ) or more (claim 17 ).

  The lithium nickel manganese cobalt-based composite oxide powder for 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 and improved load characteristics. Can be planned. For this reason, according to the present invention, a lithium secondary battery that is inexpensive, highly safe, and excellent in performance even when used at a high charging voltage is provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to the gist of the present invention. The content of is not specified.

[Lithium nickel manganese cobalt based composite oxide powder]
The lithium nickel manganese cobalt-based composite oxide powder for a lithium secondary battery positive electrode material of the present invention has a composition represented by the following formula (I) and includes a crystal structure belonging to a layered structure. In the powder X-ray diffraction measurement used, 0.01 ≦ FWHM (110) ≦ 0. 0 when the half-value width of the (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° is FWHM (110). It is represented by 2.
Li [Li _{z / (2 + z)} {(Ni _{(1 + y) / 2} Mn _{(1-y) / 2} ) _1-x Co _x } _{2 / (2 + z)} ] O ₂ (I)
(However, in the composition formula (I),
0 ≦ x ≦ 0.1
−0.1 ≦ y ≦ 0.1
(1-x) (0.05-0.98y) ≤z≤ (1-x) (0.15-0.88y)
It is. )

<Composition and crystal structure>
In the formula (I), the value of x is 0 or more, preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more, most preferably 0.04 or more, 0.1 or less, Preferably it is 0.099 or less.

  The value of y is -0.1 or more, preferably -0.08 or more, more preferably -0.05 or more, most preferably -0.03 or more, 0.1 or less, preferably 0.08 or less, more preferably Is 0.05 or less, most preferably 0.03 or less.

  The value of z is (1-x) (0.05-0.98y) or more, preferably (1-x) (0.06-0.98y) or more, more preferably (1-x) (0.07). -0.98y) or more, most preferably (1-x) (0.08-0.98y) or more, (1-x) (0.15-0.88y) or less, preferably (1-x) ( 0.145-0.88y) or less, more preferably (1-x) (0.14-0.88y), most preferably (1-x) (0.13-0.88y) or less. If z is below this lower limit, the conductivity will decrease, and if it exceeds the upper limit, the amount of substitution to transition metal sites will increase so much that the battery capacity will decrease, leading to a decrease in the performance of lithium secondary batteries using this. There is sex. On the other hand, if z is too large, the carbon dioxide absorbability of the active material powder increases, so that 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 (I), the closer the z value is to the lower limit that is a constant ratio, the lower the rate characteristics and output characteristics of the battery, and the lower the z value is 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 lower the y value, that is, the smaller the manganese / nickel atomic ratio, the higher the capacity is obtained at a lower charging voltage. However, the cycle characteristics and safety of batteries set at a higher charging voltage tend to be reduced. As the value is closer to the upper limit, the cycle characteristics and safety of the battery set at a higher charge voltage are improved, while the discharge capacity, rate characteristics, and output characteristics tend to decrease. In addition, the closer the x value is to the lower limit, the lower the load characteristics such as rate characteristics and output characteristics when the battery is used. Conversely, the closer the x value is to the upper limit, the rate characteristics when the battery is used. However, if this upper limit is exceeded, the cycle characteristics and safety when set at a high charge voltage are reduced, and the raw material cost is increased. Setting the composition parameters x, y, and z within a specified range is an important component of the present invention.
In the composition of the formula (I), the atomic ratio of the oxygen amount is set to 2 for convenience, but there may be some non-stoichiometry. For example, the atomic ratio of oxygen can be in the range of 2 ± 0.1.

  Further, foreign elements may be introduced into the lithium nickel manganese cobalt based composite oxide powder of the present invention. The different elements include B, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Ru, Rh, and Pd. , Ag, In, Sn, Sb, Te, Ba, Ta, W, 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.

（以下「層状Ｒ（−３）ｍ構造」と表記することがある。）に帰属される。 The lithium nickel manganese cobalt based composite oxide of the present invention includes 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. In addition to this, LiMnO ₂ called so-called layered Mn is an orthorhombic and space-group Pm2m layered compound, and Li ₂ MnO ₃ called so-called 213 phase is 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.

Here, the chemical meaning of the Li composition (z and x) in the lithium nickel manganese cobalt based composite oxide of the present invention will be described in more detail below.
As described above, the layered structure is not necessarily limited to the R (-3) m structure, but is preferably one that can be attributed to the R (-3) m structure from the viewpoint of electrochemical performance.
In order to obtain x, y, and z in the composition formula of the lithium nickel manganese cobalt based composite oxide, each transition metal and Li are analyzed with an inductively coupled plasma emission spectrometer (ICP-AES), and Li / Ni / Calculated by determining the ratio of Mn / Co.

  From a structural point of view, it is considered that Li related to z is substituted for the same transition metal site. Here, due to Li related to z, the average valence of Ni becomes larger than divalent (trivalent Ni is generated) by the principle of charge neutrality. Since z raises the Ni average valence, it becomes an index of the Ni valence (the ratio of Ni (III)).

となる。この計算結果は、Ｎｉ価数はｚのみで決まるのではなく、ｘ及びｙの関数となっていることを意味している。ｚ＝０かつｙ＝０であれば、ｘの値に関係なくＮｉ価数は２価のままである。ｚが負の値になる場合は、活物質中に含まれるＬｉ量が化学量論量より不足していることを意味し、あまり大きな負の値を有するものは本発明の効果が出ない可能性がある。一方、同じｚ値であっても、Ｎｉリッチ（ｙ値が大きい）及び／又はＣｏリッチ（ｘ値が大きい）な組成ほどＮｉ価数は高くなるということを意味し、電池に用いた場合、レート特性や出力特性が高くなるが、反面、容量低下しやすくなる結果となる。このことから、ｚ値の上限と下限はｘ及びｙの関数として規定するのがより好ましいと言える。 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. If z = 0 and y = 0, the Ni valence remains divalent regardless of the value of x. When z is a negative value, it means that the amount of Li contained in the active material is less than the stoichiometric amount, and those having a very large negative value may not have the effect of the present invention. There is sex. On the other hand, even if the z value is the same, it means that the Ni valence becomes higher as the composition is rich in Ni (large y value) and / or rich in Co (large x value). The rate characteristics and output characteristics are improved, but on the other hand, the capacity tends to decrease. From this, it can be said that it is more preferable to define the upper and lower limits of the z value as a function of x and y.

  In addition, when the x value is in the range of 0 ≦ x ≦ 0.1 and the amount of Co is small, in addition to reducing the cost, it was used as a lithium secondary battery designed to be charged at a high charging potential. In some cases, charge / discharge capacity, cycle characteristics, and safety are improved.

  As described above, the battery using the lithium nickel manganese cobalt based composite oxide powder having the above composition as the positive electrode active material has the disadvantage that the conventional rate and output performance are inferior. However, the lithium nickel manganese cobalt based composite oxidation of the present invention is disadvantageous. In addition to the fact that the product is highly crystalline and the existence ratio of the heterogeneous phase is extremely low, the amount of mercury intrusion at the time of pressurization in the mercury intrusion curve is large and the pore volume between crystal grains is large. When a battery is produced by using this, it is possible to increase the contact area between the surface of the positive electrode active material and the electrolytic solution or the conductive additive, so that the load characteristics required as the positive electrode active material can be improved.

<Powder X-ray diffraction peak>
The lithium nickel manganese cobalt based composite oxide powder of the present invention has a FWHM of the half width of the (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° in a powder X-ray diffraction pattern using CuKα rays. (110), 0.01 ≦ FWHM (110) ≦ 0.2.
In general, since the half width of the X-ray diffraction peak is used as a measure of crystallinity, the present inventors have intensively investigated the correlation between crystallinity and battery performance. As a result, it has been found that when the half-value width of the (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° is within the specified range, good battery performance is exhibited.

  In the present invention, 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, and most preferably 0.14 or more, 0.2 or less. More preferably, it is 0.196 or less, More preferably, it is 0.19 or less, Most preferably, it is 0.185 or less.

The lithium nickel manganese cobalt based composite oxide powder of the present invention has a diffraction angle 2θ of around 64 ° in the powder X-ray diffraction measurement using CuKα ray (018) diffraction peak, around 64.5 °. (110) and (113) diffraction peak present at around 68 ° do not have a diffraction peak derived from a different phase, or have a diffraction peak derived from a different phase at a higher angle than the top of each peak. When it has, it is preferable that the integrated intensity ratio of the heterophase peak to the diffraction peak of the original crystal phase is in the following range, respectively.
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.20
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25
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 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 ≦ 0.20, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25, I ₁₁₃ ^* / I ₁₁₃ ≦ 0.30, preferably I ₀₁₈ ^* / I ₀₁₈ ≦ 0. 15, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.20, I ₁₁₃ ^* / I ₁₁₃ ≦ 0.25, more preferably I ₀₁₈ ^* / I ₀₁₈ ≦ 0.10, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.16, I ₁₁₃ ^* / _{I 113} ≦ 0.20, more preferably ^{_{I 018 * / I 018 ≦ 0.05}} , I 110 * / I 110 ≦ 0.10, an _{I 113 * / I 113 ≦ 0.15} , It is particularly preferred is also preferably no diffraction peaks derived from heterogeneous phases.

<Pore characteristics by mercury intrusion method>
The lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material of the present invention preferably satisfies a specific condition in measurement by mercury porosimetry.

The mercury intrusion method employed in the evaluation of the lithium nickel manganese cobalt based composite oxide powder of the present invention will be described below.
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 shape of the pore 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 extruding mercury from 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.

The particles of 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 0.7 cm ³ / g or more, it is 1.5 cm ³ / g or less preferable. Mercury intrusion volume is more preferably 0.74 cm ³ / g or more, more preferably 0.8 cm ³ / g or more, and most preferably 0.9 cm ³ / g or more, more preferably 1.4 cm ³ / g or less, More preferably, it is 1.3 cm < ³ > / g or less, Most preferably, it is 1.2 cm < ³ > / g or less. When the upper limit of this range is exceeded, the voids become excessive, and when the lithium nickel manganese cobalt based composite oxide powder of the present invention is used as the positive electrode material, the positive electrode active material filling rate in the positive electrode plate (positive electrode current collector) Becomes low, and the battery capacity is limited. On the other hand, when the value falls below the lower limit of this range, voids between particles become too small. Therefore, when a battery is produced using the lithium nickel manganese cobalt based composite oxide powder of the present invention as a positive electrode material, lithium between particles Diffusion is hindered and load characteristics are degraded.

In the lithium nickel manganese cobalt based composite oxide powder of the present invention, when a pore distribution curve is measured by the mercury intrusion method, 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. In particular, a pore distribution curve obtained by measuring the lithium nickel manganese cobalt based composite oxide powder of the present invention by a mercury intrusion method is referred to as “a 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 a peak 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 300 nm or more, preferably 350 nm or more, most preferably 400 nm or more, and usually 1000 nm or less, preferably 980 nm or less. Preferably it exists in the range of 970 nm or less, more preferably 960 nm or less, and most preferably 950 nm or less. When the upper limit of this range is exceeded, when a battery is prepared using the lithium nickel manganese cobalt composite oxide powder of the present invention as the positive electrode material, lithium diffusion in the positive electrode material is inhibited, or the conductive path is insufficient. The load characteristics may be reduced. On the other hand, below the lower limit of this range, when a positive electrode is produced using the lithium nickel manganese cobalt composite oxide powder of the present invention, the required amount of conductive material and binder increases, and the positive electrode plate (positive electrode) Of the positive electrode active material in the current collector) may be 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 having a peak top at a pore radius of 300 nm or more and 1000 nm or less, which the pore distribution curve according to the present invention has, is preferably usually 0.3 cm ³ / g or more, preferably 0.35 cm ³ / g or more, more preferably 0.4 cm ³ / g or more, most preferably 0.5 cm ³ / g or more and usually 1.0 cm ³ / g or less, preferably 0.8 cm ³ / g , more preferably 0.7 cm ³ / g or less, and most preferably not more than 0.6 cm ³ / g. When the upper limit of this range is exceeded, the voids become excessive, and when the lithium nickel manganese cobalt based composite oxide powder of the present invention is used as the positive electrode material, the filling rate of the positive electrode active material into the positive electrode plate becomes low, and the battery Capacity may be constrained. On the other hand, when the lower limit of this range is not reached, voids between particles become excessively small. Therefore, when a battery is produced using the lithium nickel manganese cobalt based composite oxide powder of the present invention as a positive electrode material, Lithium diffusion is inhibited, and the load characteristics 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, but preferably does not exist within the pore radius range of 80 nm or more and 300 nm or less.

<Reason why the lithium nickel manganese cobalt based composite oxide powder of the present invention provides the above effects>
Although the details of the reason why the lithium nickel manganese cobalt based composite oxide powder of the present invention brings about the above-mentioned effects are not clear, in addition to the highly developed crystallinity, the optimum region in terms of composition In addition, since the pore volume is reasonably large, it is possible to increase the contact area between the surface of the positive electrode active material and the electrolyte when a battery is produced using this, so it is necessary as a positive electrode active material. It is estimated that the load characteristics are improved.

<Other preferred embodiments>
In the following description, other suitable characteristics of the lithium nickel manganese cobalt based composite oxide powder of the present invention will be described. However, this is only a preferable aspect, and the present invention can be used as long as it has the above-described characteristics. Other characteristics of the lithium nickel manganese cobalt based composite oxide powder are not particularly limited.

(Median diameter and 90% integrated diameter ( _D90 ))
The median diameter of the lithium nickel manganese cobalt based composite oxide powder of the present invention is usually 1 μm or more, preferably 1.2 μm or more, more preferably 1.5 μm or more, most preferably 2 μm or more, and usually 5 μm or less, preferably 4 0.5 μm or less, more preferably 4 μm or less, still more preferably 3.8 μm or less, and most preferably 3.5 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.

The 90% cumulative diameter (D ₉₀ ) of the secondary particles of the lithium nickel manganese cobalt based composite oxide powder of the present invention is usually 10 μm or less, preferably 9 μm or less, more preferably 8 μm or less, and most preferably 7 μm or less. Usually, it is 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and most preferably 3.5 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).

(The bulk density)
The bulk density of the lithium nickel manganese cobalt based composite oxide powder of the present invention is usually 0.5 g / cc or more, preferably 0.6 g / cc or more, more preferably 0.7 g / cc or more, most preferably 0.8 g. / Cc or more, usually 1.7 g / cc or less, preferably 1.6 g / cc or less, more preferably 1.5 g / cc or less, and most preferably 1.3 g / cc 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. If the bulk density is below this lower limit, there is a possibility of adversely affecting the powder filling property and electrode preparation.
In the present invention, the bulk density is a powder packing density (tap density) when 5 to 10 g of lithium nickel manganese cobalt based composite oxide powder is put in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm. ) Determined as g / cc.

(BET specific surface area)
The lithium nickel manganese cobalt based composite oxide powder of the present invention has a BET specific surface area of usually 1.4 m ² / g or more, preferably 1.5 m ² / g or more, more preferably 1.6 m ² / g or more. Most preferably, it is 1.7 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, and most preferably 2.3 m ² / g. It is as follows. 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 is heated and degassed with a nitrogen / helium 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. The adsorbed nitrogen gas was desorbed, the amount was detected by a heat conduction detector, and the specific surface area of the sample was calculated from this.

(Contained carbon concentration C)
The carbon concentration C (wt%) value of the lithium nickel manganese cobalt composite oxide powder of the present invention is usually 0.005 wt% or more, preferably 0.01 wt% or more, more preferably 0.015 wt%. Above, most preferably 0.02% by weight or more, usually 0.05% by weight or less, preferably 0.045% by weight or less, more preferably 0.04% by weight or less, most preferably 0.035% by weight or less. It is. 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, from the concentration of carbon contained in the lithium nickel manganese cobalt composite oxide powder obtained by carbon analysis described later, a numerical value assuming that all of the carbon is derived from carbonate ions, and the lithium nickel manganese cobalt composite analyzed by ion chromatography It is considered that carbon in the oxide powder is generally present as a carbonate, and therefore the C value can be regarded as indicating information on the amount of carbonate compound, particularly lithium carbonate.

On the other hand, when conducting a composite treatment with conductive carbon as a technique for further increasing the electronic conductivity, a C amount exceeding the specified range may be detected, but such a treatment was performed. The C value of the lithium nickel manganese cobalt based composite oxide powder is not limited to the above specified range.
On the other hand, in the lithium nickel manganese cobalt-based composite oxide powder defined by the present invention, a very small amount of lithium is present as a carbonate, which affects the lithium composition (z) defined by the composite oxide powder. Absent.

(Average primary particle size)
The average primary particle size of the lithium nickel manganese cobalt composite oxide powder of the present invention is preferably 0.05 μm or more and 1 μm or less. The lower limit is more preferably 0.1 μm or more, further preferably 0.15 μm or more, most preferably 0.2 μm or more, and the upper limit is more preferably 0.8 μm or less, still more preferably 0.7 μm or less, most preferably Is 0.5 μm or less. 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. 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 (average particle diameter of primary particles) in the present invention is an average diameter observed with a scanning electron microscope (SEM), and about 10 to 30 particles using a SEM image of 30,000 times. The average particle diameter of primary particles can be obtained.

(Volume resistivity)
The volume resistivity value when the lithium nickel manganese cobalt based composite oxide powder of the present invention is compacted at a pressure of 40 MPa is preferably 1 × 10 ³ Ω · cm or more as the lower limit, and is preferably 5 × 10 ³ Ω · cm. More preferably, it is more than cm, and more preferably 1 × 10 ⁴ Ω · cm. The upper limit is preferably 1 × 10 ⁶ Ω · cm or less, more preferably 5 × 10 ⁵ Ω · cm or less, and further preferably 1 × 10 ⁶ 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 nickel manganese cobalt based composite oxide powder is four probe / ring electrode, electrode spacing 5.0 mm, electrode radius 1.0 mm, sample radius 12.5 mm, and applied voltage. It is a volume resistivity measured in a state where the limiter is 90 V and the lithium nickel manganese cobalt based composite oxide 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.

[Method for producing lithium nickel manganese cobalt based composite oxide powder for positive electrode material of lithium secondary battery]
The method for producing the lithium nickel manganese cobalt based composite oxide powder of the present invention is not limited to a specific production method. For example, a lithium compound, a nickel compound, a manganese compound, and a cobalt compound are dispersed in a liquid medium. After spray drying the slurry, the mixture can be fired to produce. In particular, a slurry preparation step of obtaining a slurry in which a lithium compound, a nickel compound, a manganese compound, and a cobalt compound are pulverized in a liquid medium and uniformly dispersed therein, and a spray drying step of spray drying the obtained slurry And a firing step of firing the obtained spray-dried body in an oxygen-containing gas atmosphere at a temperature T (° C.) of 940 ° C. ≦ T ≦ 1200 ° C. The lithium nickel manganese cobalt based composite oxide powder is preferably produced by the production method.
Below, the manufacturing method of the lithium nickel manganese cobalt type complex oxide powder of this invention is demonstrated in detail.

<Slurry preparation process>
Among the raw material compounds used in the preparation of the slurry for producing lithium nickel manganese cobalt based composite oxide powder by the method of the present invention, the lithium compounds include Li ₂ CO ₃ , 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 acids Li, citric acid Li, fatty Li, alkyllithium or the like. Among these lithium compounds, lithium compounds containing no nitrogen atom, sulfur atom, or halogen atom are preferable because they do not generate harmful substances such as SO _x and NO _x during the firing treatment. It is a compound that tends to form voids by generating cracked gas in secondary particles of spray-dried powder due to generation of cracked gas. Considering these points, Li ₂ CO ₃ , LiOH, among others , LiOH · _{H 2} O is, inter alia easy to handle, preferably _Li 2 CO ₃ because it is relatively inexpensive. These lithium compounds may be used individually by 1 type, and may use 2 or more types together.

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 _{2 are} not used in the generation of harmful substances such as SO _x and NOX during the firing process. Nickel compounds such as 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 generation of decomposition gas during firing, spray-dried powder 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. 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 in terms of not generating harmful substances such as SO _x and NOX during the firing step, more preferably 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 to the above Li, Ni, Mn, and Co raw material compounds, other elements are substituted to introduce the above-mentioned foreign elements, and voids in secondary particles formed by spray drying described later are efficiently formed. It is possible to use a group of compounds intended to be used. In addition, the addition stage of the compound used for the purpose of efficiently forming the voids of the secondary particles used here can be selected either before or after mixing the raw materials depending on the property. It is. In particular, it is preferable to add a compound that is easily decomposed due to mechanical shear stress applied by the mixing step after the mixing step.

The method for mixing the raw materials is not particularly limited, and may be wet or dry. 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.
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) 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 0.3 μm or less, preferably 0.25 μm or less, and most preferably 0.2 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 the cost of pulverization, so that the average particle size is usually 0.01 μm or more, preferably 0.02 μm or more, more preferably 0.05 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 powder 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 a lithium nickel manganese cobalt based composite oxide powder of the present invention, primary particles are aggregated to form secondary particles by spray drying a slurry obtained by wet pulverizing a raw material compound. To obtain a powder. The spray-dried powder formed by agglomerating primary particles to form secondary particles is a shape 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 15 μm or less, more preferably Is 12 μm or less, more preferably 9 μm or less, and most preferably 7 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 5 μm or more, more preferably 6 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.

  That is, for example, after a slurry in which a lithium compound, a nickel compound, a manganese compound, and a cobalt compound are dispersed in a liquid medium is spray-dried, the obtained powder is fired to obtain a lithium nickel manganese cobalt composite oxide powder. When the slurry viscosity during spray drying is V (cp), 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 Spray drying is performed under the condition that ≦ 4000 cp and the gas-liquid ratio G / S is 1500 ≦ G / S ≦ 5000.

  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.

  Further, when the gas-liquid ratio G / S is lower than the lower limit, the secondary particle size is likely to be coarsened or the drying property is liable to be lowered, and when it exceeds the upper limit, the productivity may be lowered. Therefore, the gas-liquid ratio G / S is usually 1500 or more as a lower limit, preferably 1600 or more, more preferably 1700 or more, most preferably 1800 or more, and the upper limit is usually 5000 or less, preferably 4700 or less. Preferably it is 4500 or less, Most preferably, it is 4200 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 200 ° C. It is preferable to carry out the reaction at a temperature of ℃ or less, most preferably 180 ℃ or less. 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, the spray-dried powder of lithium nickel manganese cobalt based composite oxide powder according to the present invention is characterized by a weak cohesion between primary particles, which examines changes in median diameter accompanying ultrasonic dispersion. Can be confirmed. Here, the upper limit of the median diameter of spray-dried particles when measured after applying ultrasonic dispersion “Ultra Sonic” (output 30 W, frequency 22.5 kHz) for 5 minutes is usually 4 μm or less, preferably 3.5 μm or less. More preferably, it is 3 μm or less, more preferably 2.5 μm or less, most preferably 2 μm or less, and the lower limit is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, most preferably It is 0.2 μm or more. Lithium nickel manganese cobalt composite oxide particles fired using spray-dried particles having a median diameter after ultrasonic dispersion larger than the above value have few voids between the particles, and the load characteristics are not improved. On the other hand, lithium nickel manganese cobalt-based composite oxide particles fired using spray-dried particles whose median diameter after ultrasonic dispersion is smaller than the above values have too many voids between them, resulting in a decrease in bulk density. There is a possibility that problems such as poor coating properties may occur.

  Further, the bulk density of the spray-dried powder of the lithium nickel manganese cobalt composite oxide powder for a lithium secondary battery positive electrode material of the present invention is usually 0.1 g / cc or more, preferably 0.3 g / cc or more, more preferably 0.5 g / cc or more, most preferably 0.7 g / cc or more. Below this lower limit, there is a possibility of adversely affecting powder filling properties and powder handling, and is usually 1.7 g / cc or less, preferably 1.6 g / cc or less, more preferably 1.5 g / cc. Hereinafter, it is most preferably 1.4 g / cc or less. The bulk density exceeding this upper limit is preferable for powder filling properties and powder handling, but the specific surface area may be too low, and the reactivity in the firing step may be reduced.

In addition, if the powder obtained by spray drying has a small specific surface area, the reactivity between the raw material compounds is reduced in the next firing step, so as described above, the starting material is pulverized before spray drying, etc. It is preferable that the specific surface area be increased as much as possible by the above means. On the other hand, if the specific surface area is excessively increased, not only is it industrially disadvantageous, but the lithium nickel manganese cobalt based composite oxide of the present invention may not be obtained. Accordingly, the spray-dried powder thus obtained has a BET specific surface area of usually 10 m ² / g or more, preferably 20 m ² / g or more, more preferably 30 m ² / g or more, and most preferably 50 m ² / g or more. In general, it is preferably 100 m ² / g or less, preferably 80 m ² / g or less, more preferably 70 m ² / g or less, and most preferably 65 m ² / g or less.

<Baking process>
The fired precursor thus obtained is then fired.
Here, in the present invention, the “firing precursor” means a precursor of a lithium nickel manganese cobalt based 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 lithium compound raw material used, but as a tendency, if the firing temperature is too high, the primary particles grow excessively, the sintering between the particles proceeds too much, and the specific surface area is small. Too much. 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. Accordingly, the firing temperature is usually 940 ° C. or higher, preferably 950 ° C. or higher, more preferably 960 ° C. or higher, most preferably 970 ° C. or higher, usually 1200 ° C. or lower, preferably 1175 ° C. or lower, more preferably 1150 ° C. Hereinafter, it is most preferably 1125 ° C. or lower.

  For firing, for example, a box furnace, a tubular furnace, a tunnel 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 crushing step meaning 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 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 rate of temperature rise is preferably 2 ° C./min or more, more preferably 3 ° C./min or more, preferably 7 ° C./min or less, more preferably 5 ° C./min or less.

  Although the holding time in the maximum temperature holding step varies depending on the temperature, it is usually 30 minutes or more, preferably 1 hour or more, more preferably 3 hours or more, most preferably 5 hours or more within the above-mentioned temperature range, and 50 Time or less, preferably 25 hours or less, more preferably 20 hours or less, and most preferably 15 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 the temperature lowering rate is too slow, it takes time and is industrially disadvantageous, but if it is too fast, the uniformity of the target product tends to be lost 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.

  As an atmosphere during firing, an oxygen-containing gas atmosphere such as air can be used. 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 nickel manganese cobalt based composite oxide powder having the specific composition of the present invention, when the production conditions are constant, a lithium compound, a nickel compound, a manganese compound The target Li / Ni / Mn / Co molar ratio can be controlled by adjusting the mixing ratio of each compound in preparing a slurry in which a cobalt compound is dispersed in a liquid medium.
According to the lithium nickel manganese cobalt based composite oxide powder thus obtained, there is little swelling due to gas generation, high capacity, excellent load characteristics such as rate and output, low temperature output characteristics, and storage characteristics. An excellent positive electrode material for a lithium secondary battery with good performance balance is provided.

[Positive electrode for lithium secondary battery]
The positive electrode for a lithium secondary battery of the present invention is formed by forming a positive electrode active material layer containing a lithium nickel manganese cobalt composite oxide powder for a lithium secondary battery positive electrode material of the present invention and a binder on a current collector. It will be.

  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 Copolymer and its hydrogenated thermoplastic elastomeric polymer, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer, etc. Fluorine polymers such as soft resinous 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.

  The liquid medium for forming the slurry is to dissolve or disperse the lithium nickel manganese cobalt composite oxide powder, which is the positive electrode material, the binder, and the conductive material and thickener used as necessary. As long as the solvent can be used, the type is not particularly limited, and either an aqueous solvent or an organic solvent may be used. 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 ratio of the lithium nickel manganese cobalt composite oxide 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. Usually, it is 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 the above-described positive electrode for a lithium secondary battery of the present invention capable of occluding and releasing lithium, a negative electrode capable of occluding and releasing lithium, and a non-aqueous electrolyte using a lithium salt as an electrolytic salt, Is provided. 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, 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, which is 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) 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 or less, preferably Is preferably 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, particularly preferably 0.1% by weight or less, based on the weight of the graphite material.

  Further, the crystallite size (Lc) of the graphite material determined by X-ray diffraction by the Gakushin method is usually 30 nm or more, preferably 50 nm or more, and 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 _{P A} is detected in the range of 1580～1620Cm ^-1, it is detected in the range of 1350 ^-1 that intensity ratio _I a / _{I B} of the intensity _{I B} of a peak _{P B} is what is preferably 0 to 0.5. 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.

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.

<Charge potential of the positive electrode when fully charged>
The lithium secondary battery of the present invention is preferably designed such that the charging potential of the positive electrode in a fully charged state is 4.35 V (vs. Li / Li ⁺ ) or higher. That is, the lithium nickel manganese cobalt composite oxide powder for a lithium secondary battery positive electrode material of the present invention is charged at a high charging potential of 4.35 V (vs. Li / Li ⁺ ) or more by the above-described specific composition. When used in a lithium secondary battery designed as described above, the effect of improving cycle characteristics and safety is effectively exhibited. However, it is also possible to use the charging potential as less than 4.35V.

  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 nickel manganese cobalt based composite oxide powders manufactured in each of Examples and Comparative Examples described below were measured as follows.

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

<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 integral intensity of heterophase peak / original crystal phase peak and Calculation of integral intensity ratio>
It calculated | required by the powder X-ray-diffraction measurement using the CuK (alpha) ray described below. Profile fitting was performed on the (018), (110), and (113) diffraction peaks derived from the hexagonal system R-3m (No. 166) observed in each sample, and integrated intensity, integrated intensity ratio, and the like were calculated.
・ Calculation of half width and area uses the diffraction pattern when measured in the fixed slit mode of the concentration method ・ The actual XRD measurement (Example, Comparative Example) is measured in the variable slit mode, variable → fixed Data conversion is performed.-Conversion from variable to fixed is based on the formula of intensity (fixed) = intensity (variable) / sin θ (powder X-ray diffraction measurement device specification)
Device name: X'Pert Pro MPD manufactured by PANallytical, Netherlands
Optical system: Concentrated optical system (optical system specification)
Incident side: Enclosed X-ray tube (CuKα)
Soller Slit (0.04 rad)
Divergence Slit (Variable Slit)
Sample stage: Rotating sample stage (Spinner)
Light receiving side: Semiconductor array detector (X'Celerator)
Ni-filter
Gonio radius: 243mm
(Measurement condition)
X-ray output (CuKα): 40 kV, 30 mA, scanning axis: θ / 2θ
Scanning range (2θ): 10.0-75.0 °
Measurement mode: Continuous
Reading width: 0.015 °, counting time: 99.7 sec
Automatic variable slit (Automatic-DS: 10 mm (irradiation width))
Lateral divergence mask: 10 mm (irradiation width)

<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 °.

<Average primary particle size>
It calculated | required from the SEM image of 30,000 times.
<Median diameter of secondary particles>
Measurements were made 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.
<Specific surface area>
Obtained by BET method.
<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.

<Volume resistivity>
Using a powder resistivity measurement device (Dia Instruments: Lorester GP powder low efficiency measurement system PD-41), the sample weight is 3 g, and a powder probe unit (four probe / ring electrode, electrode spacing 5.0 mm) The electrode resistivity is 1.0 mm, the sample radius is 12.5 mm, and 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.

<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 6 g of sample powder was put in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm.

[Production of Lithium Transition Metal Compound Powder (Examples and Comparative Examples)]
Example 1
Weigh Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , and CoOOH so that the molar ratio of Li: Ni: Mn: Co = 1.10: 0.45: 0.45: 0.10 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 0.16 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 13 wt%, viscosity 1350 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 11 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 4091). 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 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then crushed. The volume resistivity is 2.7 × 10 ⁴ Ω · cm, the carbon concentration C is 0.023 wt%, and the composition is Li _1.096 (Ni _0.458 Mn _0.444 Co _0.098 ) O _2. Lithium nickel manganese cobalt composite oxide (x = 0.098, y = 0.016, z = 0.096) having a layered structure was obtained. The lithium nickel manganese cobalt based composite oxide powder has an average primary particle size of 0.6 μm, a median diameter of 3.0 μm, a 90% cumulative diameter (D ₉₀ ) of 5.1 μm, and a bulk density of 1.2 g / cc. The BET specific surface area was 1.7 m ² / g.

(Example 2)
Weigh Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , and CoOOH so that the molar ratio of Li: Ni: Mn: Co = 1.10: 0.45: 0.45: 0.10 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 0.16 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 13 wt%, viscosity 1350 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the dry gas at this time, the dry gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ L / min (gas-liquid ratio G / S = 4091). 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. The volume resistivity is 2.2 × 10 ⁴ Ω · cm, the carbon concentration C is 0.030 wt%, and the composition is Li _1.118 (Ni _0.456 Mn _0.445 Co _0.099 ) O _2. Lithium nickel manganese cobalt composite oxide (x = 0.099, y = 0.122, z = 0.118) having a layered structure was obtained. The lithium nickel manganese cobalt based composite oxide powder has an average primary particle size of 0.5 μm, a median diameter of 3.1 μm, a 90% cumulative diameter (D ₉₀ ) of 5.5 μm, and a bulk density of 1.1 g / cc. The BET specific surface area was 2.2 m ² / g.

(Example 3)
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: 0.45: 0.45: 0.10 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 0.16 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 13% by weight, viscosity 1310 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the dry gas at this time, the dry gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ L / min (gas-liquid ratio G / S = 4091). 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 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then crushed. The volume resistivity is 9.3 × 10 ⁴ Ω · cm, the carbon concentration C is 0.030 wt%, and the composition is Li _1.064 (Ni _0.457 Mn _0.445 Co _0.098 ) O _2. Lithium nickel manganese cobalt composite oxide (x = 0.098, y = 0.013, z = 0.064) having a layered structure was obtained. The lithium nickel manganese cobalt based composite oxide powder has an average primary particle size of 0.5 μm, a median diameter of 2.1 μm, a 90% cumulative diameter (D ₉₀ ) of 3.8 μm, and a bulk density of 1.2 g / cc. The BET specific surface area was 1.9 m ² / g.

Example 4
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 = 1.10: 0.475: 0.475: 0.05 After mixing, pure water was added to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.13 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 14% by weight, viscosity 1960 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Chemical Co., Ltd .: LT-8 type). Air was used as the dry gas at this time, the dry gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ L / min (gas-liquid ratio G / S = 4091). 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 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then crushed. The volume resistivity is 2.6 × 10 ⁴ Ω · cm, the carbon concentration C is 0.031 wt%, and the composition is Li _1.115 (Ni _0.481 Mn _0.470 Co _0.049 ) O _2. The lithium nickel manganese cobalt composite oxide (x = 0.049, y = 0.012, z = 0.115) which has layer structure was obtained. The lithium nickel manganese cobalt based composite oxide powder has an average primary particle size of 0.4 μm, a median diameter of 3.7 μm, a 90% cumulative diameter (D ₉₀ ) of 6.1 μm, and a bulk density of 1.1 g / cc. The BET specific surface area was 1.9 m ² / g.

(Comparative Example 1)
Ni (OH) ₂ , Mn ₃ O ₄ , and Co (OH) ₂ were weighed and mixed so as to have a molar ratio of Ni: Mn: Co = 0.45: 0.45: 0.10. Pure water was added to the slurry to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.15 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 12% by weight, viscosity 700 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). At this time, air was used as the dry gas, the dry gas introduction amount G was 30 L / min, and the slurry introduction amount S was 38 × 10 ⁻³ L / min (gas-liquid ratio G / S = 789). The drying inlet temperature was 150 ° C.
LiOH powder pulverized to a median diameter of 20 μm or less was added to and mixed with the particulate powder obtained by spray drying as described above. About 13.1 g of this mixed powder was put into an alumina crucible, fired at 950 ° C. for 10 hours under air flow (temperature raising / lowering rate 5 ° C./min.), And then crushed to have a volume resistivity of 1.7 × Lithium nickel manganese cobalt composite having a layered structure of 10 ⁴ Ω · cm, carbon content C of 0.031 wt%, and composition of Li _1.130 (Ni _0.443 Mn _0.453 Co _0.105 ) O ₂ An oxide (x = 0.105, y = −0.010, z = 0.130) was obtained. The lithium nickel manganese cobalt based composite oxide powder has an average primary particle size of 0.5 μm, a median diameter of 11.1 μm, a 90% cumulative diameter (D ₉₀ ) of 18.4 μm, and a bulk density of 1.8 g / cc. The BET specific surface area was 1.3 m ² / g.

(Comparative Example 2)
Li ₂ CO ₃ , Ni (OH) ₂ , and Mn ₃ O ₄ were weighed and mixed so as to have a molar ratio of Li: Ni: Mn = 1.10: 0.50: 0.50. Pure water was added to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.14 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 13 wt%, viscosity 1270 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the dry gas at this time, the dry gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ L / min (gas-liquid ratio G / S = 4091). 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 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then crushed. And a layered structure having a volume resistivity of 2.4 × 10 ⁴ Ω · cm, a carbon concentration C of 0.044 wt%, and a composition of Li _1.081 (Ni _0.505 Mn _0.495 ) O _2. Lithium nickel manganese composite oxide (x = 0, y = 0.010, z = 0.081) was obtained. The average primary particle diameter of this lithium nickel manganese composite oxide powder is 0.4 μm, the median diameter is 1.4 μm, the 90% cumulative diameter (D ₉₀ ) is 2.1 μm, the bulk density is 1.0 g / cc, BET The specific surface area was 2.7 m ² / g.

(Comparative Example 3)
Li ₂ CO ₃ , Ni (OH) ₂ , and Mn ₃ O ₄ were weighed and mixed so as to have a molar ratio of Li: Ni: Mn = 1.15: 0.50: 0.50. Pure water was added to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.14 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 13% by weight, viscosity 1020 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the dry gas at this time, the dry gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ L / min (gas-liquid ratio G / S = 4091). 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 1000 ° C. for 6 hours in an air atmosphere (heating temperature rate 3.33 ° C./min.), And then crushed. And a layered structure having a volume resistivity of 2.1 × 10 ⁴ Ω · cm, a carbon concentration C of 0.045 wt%, and a composition of Li _1.166 (Ni _0.505 Mn _0.495 ) O _2. Lithium nickel manganese composite oxide (x = 0, y = 0.008, z = 0.166) was obtained. The lithium nickel manganese composite oxide powder has an average primary particle size of 0.5 μm, a median diameter of 3.3 μm, a 90% cumulative diameter (D ₉₀ ) of 5.6 μm, a bulk density of 1.2 g / cc, and a BET. The specific surface area was 1.9 m ² / g.

  Tables 1, 2, 3, and 4 show the compositions and physical properties of the lithium nickel manganese cobalt based composite oxide powders or lithium nickel manganese composite oxide powders produced in the above Examples and Comparative Examples. Table 4 shows the powder properties of the spray-dried powder that is the firing precursor.

  Moreover, the pore distribution curves of the lithium nickel manganese cobalt composite oxide powder or lithium nickel manganese composite oxide powder produced in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in FIGS. SEM images (photographs) (magnification × 10,000) are shown in FIGS. 8 to 14, respectively, and powder X-ray diffraction patterns are shown in FIGS.

[Production and evaluation of battery]
Using the lithium nickel manganese cobalt composite oxide powder or lithium nickel manganese composite oxide powder produced in Examples 1 to 4 and Comparative Examples 1 to 3 described above as the positive electrode material (positive electrode active material), respectively, A lithium secondary battery was prepared by the method and evaluated.

<Production of lithium secondary battery>
75% by weight of each of the lithium nickel manganese cobalt composite oxide powder or lithium nickel manganese composite oxide powder produced in Examples 1-4 and Comparative Examples 1-3, 20% by weight of acetylene black, polytetrafluoroethylene What was weighed at a ratio of 5% by weight of powder was sufficiently mixed in a mortar, and 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.

<Rate test>
For the obtained coin-type cell, in the initial two cycles, the charging upper limit voltage was set to 4.4 V, and constant current / constant voltage charging (current density: up to 4.4 V at 0.137 mA / cm ² (0.1 C)) After constant current charging, constant voltage charging was performed until 0.01 C was reached, and then the discharge lower limit voltage was set to 3.0 V, and constant current discharging (current density 0.137 mA / cm ² (0.1 C)) was performed. went. Furthermore, in the 3rd to 10th cycles, 0.2C constant current / constant voltage charging (constant current charging up to 4.4V at 0.2C and then constant voltage charging to 0.01C), 0.1C, 0.2C , 0.5C, 1C, 3C, 5C, 7C, and 9C constant current discharges were tested. However, the current corresponding to 1 C was assumed to be 150 mA per 1 g of active material. 0.1C discharge capacity (mAh / g) at the first cycle (initial discharge capacity) at this time, 0.1C discharge capacity (mAh / g) at the third cycle (discharge capacity at the third cycle) [a]), 6 1C discharge capacity (mAh / g) at the cycle (6th cycle discharge capacity [b]) and 9C discharge capacity (mAh / g) at the 10th cycle) (discharge capacity [c] at the 10th cycle) Are shown in Table 5.

  In addition, as an acceptance criterion of the examples, the initial discharge capacity in the first cycle is 175 mAh / g or more, the 0.1C discharge capacity in the third cycle is 175 mAh / g or more, and the 1C discharge capacity in the sixth cycle is 160 mAh / g. As described above, the 9C discharge capacity at the 10th cycle was set to 116 mAh / g or more.

  From Table 5, it can be seen that according to the lithium nickel manganese cobalt based composite oxide powder for the positive electrode material of the lithium secondary battery of the present invention, a lithium secondary battery excellent in load characteristics can be realized.

2 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 1. FIG. 4 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 2. FIG. 4 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 3. FIG. 6 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 4. FIG. 4 is a graph showing a pore distribution curve of a powder of lithium nickel manganese cobalt composite oxide produced in Comparative Example 1. FIG. 6 is a graph showing a pore distribution curve of a lithium nickel manganese composite oxide powder produced in Comparative Example 2. FIG. 6 is a graph showing a pore distribution curve of a powder of lithium nickel manganese composite oxide produced in Comparative Example 3. FIG. 2 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 1. FIG. 3 is a SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 2. FIG. 4 is a SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 3. FIG. 4 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 4. FIG. 2 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Comparative Example 1. FIG. 4 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese composite oxide produced in Comparative Example 2. FIG. 4 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese composite oxide produced in Comparative Example 3. FIG. 2 is a graph showing a powder X-ray diffraction pattern of the lithium nickel manganese cobalt composite oxide produced in Example 1. FIG. 4 is a graph showing a powder X-ray diffraction pattern of lithium nickel manganese cobalt composite oxide produced in Example 2. FIG. 4 is a graph showing a powder X-ray diffraction pattern of lithium nickel manganese cobalt composite oxide produced in Example 3. FIG. 6 is a graph showing a powder X-ray diffraction pattern of lithium nickel manganese cobalt composite oxide produced in Example 4. FIG. 4 is a graph showing a powder X-ray diffraction pattern of lithium nickel manganese cobalt composite oxide produced in Comparative Example 1. FIG. 6 is a graph showing a powder X-ray diffraction pattern of the lithium nickel manganese composite oxide produced in Comparative Example 2. FIG. 6 is a graph showing a powder X-ray diffraction pattern of a lithium nickel manganese composite oxide produced in Comparative Example 3.

Claims (17)

It consists of a compound represented by the following composition formula (I), is composed of a crystal structure belonging to a layered structure, and has a diffraction angle 2θ of around 64.5 ° in powder X-ray diffraction measurement using CuKα rays. When the half-value width of the (110) diffraction peak is FWHM (110), it is expressed as 0.01 ≦ FWHM (110) ≦ 0.2, and the volume resistivity value when compacted at a pressure of 40 MPa is 1 × 10 ³ Ω · cm or more, 1 × 10 lithium secondary characterized by the following der Rukoto ⁶ Omega · cm battery positive electrode material for a lithium nickel manganese cobalt based composite oxide powder.
Li [Li _{z / (2 + z)} {(Ni _{(1 + y) / 2} Mn _{(1-y) / 2} ) _1-x Co _x } _{2 / (2 + z)} ] O ₂ (I)
(However, in the composition formula (I),
0 ≦ x ≦ 0.1
−0.1 ≦ y ≦ 0.1
(1-x) (0.05-0.98y) ≤z≤ (1-x) (0.15-0.88y)
It is. )   In the composition formula (I), 0.04 ≦ x ≦ 0.099, −0.03 ≦ y ≦ 0.03, (1-x) (0.08−0.98y) ≦ z ≦ (1-x) The lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to claim 1, wherein the powder is (0.13-0.88y). In powder X-ray diffraction measurement using CuKα rays, a diffraction angle 2θ is present at a diffraction peak near 64 ° (018), a (110) diffraction peak near 64.5 °, and around 68 ° ( 113) In the case where the diffraction peak does not have a diffraction peak derived from a different phase or has a diffraction peak derived from a different phase at a higher angle side than each peak top, the integrated intensity ratio of the different phase peak to the diffraction peak of the original crystal phase The lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to claim 1 or 2, wherein each is in the following range.
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.20
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25
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.) In mercury intrusion curve obtained by mercury intrusion porosimetry, mercury penetration amount at boosting the pressure 3.86kPa to 413MPa is, 0.7 cm ³ / g or more, claim 1, characterized in that 1.5 cm ³ / g or less 4. Lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to any one of items 1 to 3.   The pore distribution curve by the mercury intrusion method has a main peak having a peak top at a pore radius of 300 nm or more and 1000 nm or less, and has no sub-peak having a peak top at a pore radius of 80 nm or more and less than 300 nm. The lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 4. 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 300 nm or more and 1000 nm or less is 0.3 cm ³ / g or more and 1.0 cm ³ / g or less. The lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 5.   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 nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 6, wherein the powder is 1 µm or more and 5 µm or less. 8. The lithium nickel manganese cobalt based composite oxide powder for a positive electrode material for a lithium secondary battery according to claim 1, wherein the bulk density is 0.5 to 1.7 g / cm ^3. . The lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 8, wherein the BET specific surface area is 1.4 to ³ m ² / g.   10. The lithium according to claim 1, wherein the C value is 0.005 wt% or more and 0.05 wt% or less when the carbon content is C (wt%). Lithium nickel manganese cobalt based composite oxide powder for secondary battery positive electrode material. 11. The lithium according to claim 1, wherein the volume resistivity when consolidated at a pressure of 40 MPa is 1 × 10 ³ Ω · cm or more and 1 × 10 ⁶ Ω · cm or less. Lithium nickel manganese cobalt based composite oxide powder for secondary battery positive electrode material.   A slurry preparation step for obtaining a slurry in which a lithium compound, a nickel compound, a manganese compound, and a cobalt compound are pulverized in a liquid medium to uniformly disperse them, and a spray drying step for spray drying the obtained slurry. A firing step of firing the spray-dried powder obtained in an oxygen-containing gas atmosphere at a temperature T (° C.) of 940 ° C. ≦ T ≦ 1200 ° C. 12. The manufacturing method of the lithium nickel manganese cobalt type complex oxide powder for lithium secondary battery positive electrode materials of description.   The method for producing a lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material according to claim 12, wherein the lithium compound is lithium carbonate. In the slurry preparation step, a lithium compound, a nickel compound, a manganese compound, and a cobalt compound are set in a liquid medium with a refractive index of 1.24 by a laser diffraction / scattering particle size distribution analyzer, and a particle diameter reference is volume. As a reference, pulverization was performed until the median diameter measured after ultrasonic dispersion for 5 minutes (output 30 W, frequency 22.5 kHz) was 0.3 μm or less, and in the spray drying process, the slurry viscosity at the time of spray drying was V (cp). Further, when the slurry supply amount is S (L / min) and the gas supply amount is G (L / min), spray drying is performed under the conditions of 50 cp ≦ V ≦ 4000 cp and 1500 ≦ G / S ≦ 5000. The manufacturing method of the lithium nickel manganese cobalt type complex oxide powder for lithium secondary battery positive electrode materials of Claim 12 or 13.   It has a positive electrode active material layer containing the lithium nickel manganese cobalt type complex oxide powder for lithium secondary battery positive electrode materials and binder as described in any one of Claims 1 thru | or 11 on a collector. A positive electrode for a lithium secondary battery. 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 15 is used as the positive electrode. A lithium secondary battery using a positive electrode for a battery. The lithium secondary battery according to claim 16 , wherein the lithium secondary battery is designed to have a charging potential of the positive electrode in a fully charged state of 4.35 V (vs. Li / Li ⁺ ) or more.

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