JP2018073751A - Positive electrode active material for nonaqueous electrolyte secondary battery, electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery high in initial efficiency.SOLUTION: An active material for a nonaqueous electrolyte secondary battery comprises a lithium transition metal composite oxide. The lithium transition metal composite oxide has an α-NaFeOstructure, of which the transition metal element (Me) includes Mn and Ni, or Mn, Ni and Co; the mole ratio (Mn/Me) of Mn to Me is given by 0.5<Mn/Me, and the mole ratio (Li/Me) of Li to Me is given by 1<Li/Me. The lithium transition metal composite oxide has an X-ray diffraction pattern which can be regarded as belonging to a space group R3-m. According to X-ray diffraction measurement by means of Cu-Kα rays, the ratio (FWHM(003)/FWHM(104)) of a half-value width (FWHM(003)) of a (003)-plane diffraction peak to a half-value width (FWHM(104)) of a (104)-plane diffraction peak is 0.45 or less, and the half-value width (FWHM(104)) of the (104)-plane diffraction peak is 0.40° or more with Miller index hkl.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a positive electrode active material for a nonaqueous electrolyte secondary battery, an electrode for a nonaqueous electrolyte secondary battery containing the positive electrode active material, and a nonaqueous electrolyte secondary battery.

Conventionally, a lithium transition metal composite oxide having an α-NaFeO ₂ type crystal structure has been studied as a positive electrode active material for a non-aqueous electrolyte secondary battery typified by a lithium secondary battery, and a non-aqueous electrolyte using LiCoO ₂ has been studied. Secondary batteries have been widely put into practical use. However, the discharge capacity of LiCoO ₂ was about 120 to 130 mAh / g. As Me, it has been desired to use abundant Mn as a global resource. However, when Mn is contained as Me when the lithium transition metal composite oxide is expressed by LiMeO ₂ (Me is a transition metal), when the molar ratio Mn / Me in Me exceeds 0.5 When charged, the structure changed to a spinel type, and the crystal structure could not be maintained. Therefore, there was a problem that the charge / discharge cycle performance was extremely inferior.

Therefore, a “LiMeO ₂ type” active material in which the molar ratio Mn / Me of transition metal (Me) is 0.5 or less and the molar ratio Li / Me of transition metal (Me) is approximately 1 is obtained. Various proposals have been made and some have been put into practical use. For example, a positive electrode active material containing LiNi _1/2 Mn _1/2 O ₂ or LiNi _1/3 Co _1/3 Mn _1/3 O ₂ which is a lithium transition metal composite oxide has a discharge capacity of 150 to 180 mAh / g. Have

On the other hand, for the so-called “LiMeO ₂ type” active material as described above, the molar ratio of Mn in Me, Mn / Me, exceeds 0.5, and the composition ratio Li of Lithium (Li) to the ratio of transition metal (Me) A so-called “lithium-rich” active material containing a lithium transition metal composite oxide having a / Me value greater than 1 is also known. (For example, refer patent documents 1, 2, 4-8).

In Patent Document 1, “having an α-NaFeO ₂ type crystal structure and represented by a composition formula Li _{1 + α} Me _1-α O ₂ (Me is a transition metal element containing Co, Ni and Mn, α> 0), A positive electrode active material for a non-aqueous electrolyte secondary battery containing a lithium transition metal composite oxide having a molar ratio Li / Me of Li to the transition metal element Me of 1.2 to 1.6, wherein the transition metal element The molar ratio Co / Me in Me is 0.02 to 0.23, the molar ratio Mn in the transition metal element Me is 0.62 to 0.72, and the potential is 5.0 V. A non-aqueous electrolyte secondary characterized by being observed as a single phase belonging to the space group R3-m on the X-ray diffraction diagram when electrochemically oxidized to (vs. Li ^/ Li ⁺ ) The positive electrode active material for a battery "(Claim 1).
In the Examples, active materials having various compositions including Li _1.13 Co _0.11 Ni _0.16 Mn _0.60 O ₂ are shown (paragraphs [0086] and [0119] Table 2). reference).

In Patent Document 2, “a compound having a layered structure and represented by the following formula (1), a columnar Li and V composite oxide having an average aspect ratio of 16 or more and 62 or less, An active material characterized by a mixture of
_{Li y Ni a Co b Mn c} M d O x ··· (1)
[In the above formula (1), the element M is at least one element selected from the group consisting of Al, Si, Zr, Ti, Fe, Mg, Nb, Ba and V, and 1.9 ≦ (a + b + c + d + y) ≦ 2.1, 1.0 <y ≦ 1.3, 0 <a ≦ 0.3, 0 <b ≦ 0.25, 0.3 ≦ c ≦ 0.7, 0 ≦ d ≦ 0.1, 9 ≦ x ≦ 2.1. ] "(Claim 1).
Then, in the embodiment, the composition is mixed with a lithium compound (positive electrode active material) and _V 2 _{O 5} is a _{Li 1.2 Ni 0.17 Co 0.08 Mn 0.55} O 2, 370 ℃ ~750 It was shown that an active material in which a Li and V composite oxide and the lithium compound were mixed was obtained by heat treatment at 0 ° C. (paragraphs [0054] to [0056], [0062] to [0065], [0072] See Table 1.

  Further, a non-aqueous electrolyte secondary battery containing a lithium transition metal composite oxide that defines FWHM003 / FWHM104 which is the half width of diffraction peaks of (003) plane and (104) plane by X-ray diffraction measurement, or a ratio thereof. Positive electrode active materials for use are known (see, for example, Patent Documents 3 to 7).

Patent Document 3 states that “a current collector and an active material layer containing active material particles held by the current collector are provided, and the active material particles are a collection of a plurality of primary particles of a lithium transition metal oxide. The secondary particle has a hollow structure having a hollow part formed inside the secondary particle and a shell part surrounding the hollow part, and the secondary particle includes the hollow part from the outside. In the powder X-ray diffraction pattern of the active material particles, the half-value width A of the diffraction peak obtained by the (003) plane and the diffraction peak obtained by the (104) plane (A / B) satisfying the following formula: (A / B) ≦ 0.7 ”(Claim 1),“ The lithium transition metal oxide is: General formula of:
Li _{1 + x} Ni _y Co _z Mn _(1-yz) W _α M _β O ₂
(X, y, z, α and β in the formula (1) are 0 ≦ x ≦ 0.2, 0.1 <y <0.9, 0.1 <z <0.4, 0.0005 ≦ It is a real number that satisfies all α ≦ 0.01 and 0 ≦ β ≦ 0.01, and M is absent or Zr, Mg, Ca, Na, Fe, Cr, Zn, Si, Sn, Al, B and One or more elements selected from the group consisting of F.)
The lithium secondary battery according to claim 1, which is a compound having a layered crystal structure represented by: (Claim 6).
The paragraphs [0073] to [0082] and [0089] Table 1 shows that the added amount of W with respect to 100 mol% of the raw material having a Ni: Co: Mn molar ratio of 0.33: 0.33: 0.33. By mixing and firing the composite hydroxide particles obtained by adjusting so as to be 0 to 0.7 mol% and lithium carbonate so that Li / Me is about 1.15, The ratio (A / B) of the half width A of the peak obtained by the diffractive surface with the Miller index (003) to the half width B of the peak obtained by the diffractive surface with the Miller index (104) is 0.38 to 1.12. It is described that an active material particle having a hollow structure or a solid structure made of a lithium transition metal composite oxide in the range of is manufactured.

In Patent Document 4, “Having a layered structure, having a composition represented by the following formula (1), a half width FWHM003 of the (003) plane and a half width FWHM104 of the (104) plane in the powder X-ray diffraction diagram. And an average primary particle diameter of 0.2 μm to 0.5 μm.
_{Li y Ni a Co b Mn c} M d O x ··· (1)
[In the above formula (1), the element M is at least one element selected from the group consisting of Al, Si, Zr, Ti, Fe, Mg, Nb, Ba and V, and 1.9 ≦ (a + b + c + d + y) ≦ 2.1, 1.0 <y ≦ 1.3, 0 <a ≦ 0.3, 0 <b ≦ 0.25, 0.3 ≦ c ≦ 0.7, 0 ≦ d ≦ 0.1, 9 ≦ x ≦ 2.1. ]
FWHM003 / FWHM104 ≦ 0.57 (2) ”(Claim 1) is described, and [0019] states that“ the above half-value width is more preferably 2θ = 18.6 ° ± 1 °. The peak half-value width FWHM003 of the diffraction peak (003) plane is 0.13 or less, the peak half-value width FWHM010 of the diffraction peak (010) plane at 2θ = 36.8 ° ± 1 ° is 0.15 or less, and 2θ The peak half-value width FWHM104 of the diffraction peak (104) at 44.5 ° ± 1 ° is 0.20 or less, and when these ranges are satisfied, a high discharge capacity is obtained.
Paragraphs [0050] to [0053], [0059] to [0062], and [0064] Table 1 has compositions such as Li _1.2 Ni _0.17 Co _0.07 Mn _0.56 O _2. In addition, a lithium compound (active material) in which FWHM003 / FWHM104 is 0.449 to 0.570 is described.

Patent Document 5 discloses a composite oxide prepared using “Li nitrate, and metal salts of M and M ′ soluble in water,
X (LiMO ₂ ) · (1-X) Li ₂ M′O ₃ (where 0 <X <1, M represents one or more kinds of average valence trivalent metals including at least Ni, and M ′ Represents at least one kind of metal having an average valence of 4 containing at least Mn.)
The diffraction peak intensity derived from a superlattice near 21 ° in X-ray diffraction measurement is defined as the crystal plane diffraction intensity of I (21 °), (003) plane, (101) plane, and (104) plane, respectively. , I (101), I (104), 0 <I (21 °) / I (003) ≦ 0.06, 2.0 ≦ I (003) / I (104) ≦ 5.0, and A composite oxide satisfying 0.4 ≦ I (101) / I (104) ≦ 0.5 simultaneously. (Claim 1), “When the half widths of the (003) plane and (104) plane are H (003) and H (104), respectively, 0.05 ° ≦ H (003) ≦ 0.2 The composite oxide according to claim 1, which simultaneously satisfies °, 0.25 ° ≦ H (104) ≦ 0.4 ° ”(claim 2).
The paragraphs [0080] to [0089] Table 1 and Paragraph [0096] Table 2 have compositions such as Li _1.2 Ni _0.235 Co _0.04 Mn _0.525 O ₂ , and (003) A composite oxide having a full width at half maximum of the plane peak of 0.115 ° to 0.226 ° and a full width at half maximum of the (104) plane peak of 0.228 ° to 0.422 ° is described.

Patent Document 6 discloses an active material for a lithium secondary battery including a solid solution of a sodium-containing lithium transition metal composite oxide having an α-NaFeO ₂ type crystal structure, wherein the chemical composition formula of the solid solution is Li _{1 + x−. y} Na _y Co _a Ni _b Mn _c O _{2 + d} (0 <y ≦ 0.1, 0.4 ≦ c ≦ 0.7, x + a + b + c = 1, 0.1 ≦ x ≦ 0.25, −0.2 ≦ d ≦ 0.2) and an X-ray diffraction pattern that can be assigned to a hexagonal crystal (space group P3 ₁ 12), and the half width of the diffraction peak on the (003) plane at the Miller index hkl is 0.30 °. The active material for a lithium secondary battery is characterized in that the half-width of the diffraction peak of the (114) plane is 0.50 ° or less ”(Claim 1).
In addition, paragraph [0052] has “half-value width of the X-ray diffraction peak described above as indicating the degree of crystallization. In the present invention, in order to improve the low temperature characteristics, the space group P3 ₁ 12 In the X-ray diffraction pattern attributed to (3), it is necessary that the half width of the (003) plane diffraction peak is 0.30 ° or less and the half width of the (114) plane diffraction peak is 0.50 ° or less. The half-value width of the (003) plane diffraction peak is preferably 0.17 ° to 0.30 °, and the half-value width of the (114) plane diffraction peak is preferably 0.35 ° to 0.50 °. It is described.
In paragraphs [0074] to [0092], [0102] Table 1, and [0103] Table 2, the composition of Li _1.09 Na _0.01 Co _0.1 Ni _0.25 Mn _0.55 O ₂ or the like is shown. And a complex oxide having a (003) plane diffraction peak half width of 0.17 to 0.32 ° and a (114) plane diffraction peak half width of 0.35 to 0.54 °. Has been.

Patent Document 7 states that “a positive electrode active material including a lithium transition metal composite oxide having an α-NaFeO ₂ structure, wherein the transition metal (Me) contains Co, Ni, and Mn. In addition, the molar ratio of Li to transition metal (Me) (Li / Me) is 1 <Li / Me, and the molar ratio of Mn to transition metal (Me) (Mn / Me) is 0.5 <Mn / Me. A positive electrode active material for a lithium secondary battery, characterized in that it contains Ce ”(Claim 1) and“ Diffraction attributed to the (104) plane in X-ray diffraction pattern analysis using a CuKα tube ” The positive electrode active material according to claim 1 or 2, wherein a peak half-value width (FWHM) is 0.269 ≦ FWHM ≦ 0.273 ”(Claim 3).
In addition, the paragraph [0031] states that “the lithium transition metal composite oxide according to the present invention is attributed to the (003) plane when the space group R3-m is used for the crystal structure model based on the X-ray diffraction pattern. The half width of the diffraction peak is preferably in the range of 0.202 ° to 0.265 °, and the half width of the diffraction peak attributed to the (104) plane is 0.265 ° to 0.285 °. The initial efficiency of the positive electrode active material can be increased by doing so. ”.
In Examples 1 to 5, after starting lithium transition metal composite oxide Li _1.18 Co _0.10 Ni _0.17 Mn _0.55 O ₂ into an acid solution containing cerium sulfate, Lithium transition metal composite containing Ce and having a half-value width FWHM (104) of 0.269 ° to 0.273 ° of the diffraction peak attributed to the (104) plane by suction filtration, drying, and further heat treatment It has been shown to obtain oxides (paragraphs [0079] to [0082], [0097] Table 1).

Patent Document 8 states that “one or more elements having a multivalent oxidation number selected from the group consisting of W, Mo, V, and Cr including a layered structure of Li ₂ MnO ₃ and a fluoro compound are doped. The positive electrode active material "(Claim 1) is described.
In the Examples, the precursor of the transition metal hydroxide is precipitated by maintaining the pH of the transition metal mixed solution prepared so that the molar ratio of Ni: Co: Mn is 2: 2: 6 at 11. It is shown that LiCO ₃ , LiF and WCl ₄ are mixed in various amounts and calcined at 750 ° C. or 700 ° C. to obtain a lithium metal composite oxide (paragraphs [0063] to [ [0065], [0074] to [0086], [0087] Table 1, [0088] Table 2).

WO2012 / 091015 JP 2013-206558 A JP 2013-51172 A JP 2013-206552 A JP 2014-10909 A WO2012 / 039413 Japanese Patent Laid-Open No. 2006-126935 JP 2014-116303 A

The discharge capacity of the so-called “lithium-rich” active material is generally larger than the so-called “LiMeO ₂ type” active material, as described in US Pat.
However, the “lithium-excess type” active material has a problem that the initial charge / discharge efficiency (hereinafter referred to as “initial efficiency”) of the nonaqueous electrolyte secondary battery using the active material is low.

  Patent Documents 1 and 2 show that the initial efficiency of the lithium secondary battery is increased, but (003) with respect to the half-value width (FWHM (104)) of the diffraction peak of (104) plane by X-ray diffraction measurement. ) Lithium transition metal in which the ratio FWHM (003) / FWHM (104) of the half width (FWHM (003)) of the diffraction peak of the surface is 0.45 or less and the FWHM (104) is 0.40 ° or more Since the positive electrode active material containing the composite oxide is not specifically shown, the initial efficiency of such a positive electrode active material cannot be predicted. In the example of Patent Document 1, it is shown that a lithium transition metal composite oxide was synthesized by mixing and calcining lithium carbonate with a coprecipitation carbonate precursor of a transition metal element containing Co, Ni and Mn. (See paragraphs [0083] to [0086], [0109], [0119] Table 2, [0120] Table 3). The positive electrode active material obtained under the synthesis conditions described in the examples of Patent Document 1 has a (003) plane diffraction peak with respect to the half-value width (FWHM (104)) of the (104) plane diffraction peak by X-ray diffraction measurement. The ratio FWHM (003) / FWHM (104) of the full width at half maximum (FWHM (003)) is 1.2 or more.

  Patent Documents 3 and 4 do not disclose a positive electrode active material containing a lithium transition metal composite oxide in which the half width of the diffraction peak of the (104) plane measured by X-ray diffraction measurement is 0.40 ° or more. There is no description about improving the initial efficiency of the secondary battery. Patent Document 3 does not specifically show a “lithium-excess” lithium transition metal composite oxide in which the molar ratio Mn / Mn in Me exceeds 0.5.

  Patent Document 5 discloses a ratio FWHM (003) of a half-value width (FWHM (003)) of a (003) plane diffraction peak to a half-value width (FWHM (104)) of a (104) plane diffraction peak by X-ray diffraction measurement. A positive electrode active material containing a lithium transition metal composite oxide having a / FWHM (104) of 0.45 or less and a FWHM (104) of 0.40 ° or more is not specifically shown. There is no description about improving the initial efficiency of the secondary battery.

  Patent Documents 6 and 7 show that the initial efficiency of the lithium secondary battery is increased, but (003) relative to the half-value width (FWHM (104)) of the diffraction peak of (104) plane by X-ray diffraction measurement. ) A positive electrode active material containing a lithium transition metal composite oxide in which the ratio FWHM (003) / FWHM (104) of the half width (FWHM (003)) of the diffraction peak of the surface is 0.45 or less is specifically shown. Therefore, the initial efficiency of such a positive electrode active material is not predictable. Patent Document 7 does not disclose that the FWHM (104) of the lithium transition metal composite oxide is 0.40 ° or more.

  Patent Document 8 describes a lithium transition metal composite oxide in which LiF is doped with one or more elements having a multivalent oxidation number selected from the group consisting of W, Mo, V, and Cr. Yes. However, the initial efficiency of the battery is not improved by the doping (see paragraph [0088] Table 2). Further, the ratio of the half-value width (FWHM (003)) of the (003) plane diffraction peak to the half-value width (FWHM (104)) of the (104) plane diffraction peak by X-ray diffraction measurement FWHM (003) / FWHM (104 ) Is 0.45 or less, and a positive electrode active material containing a lithium transition metal composite oxide in which the FWHM (104) is 0.40 ° or more is not disclosed.

  An object of the present invention is to improve initial efficiency in a nonaqueous electrolyte secondary battery.

In order to solve the above-described problem, an aspect of the present invention is “an active material for a non-aqueous electrolyte secondary battery including a lithium transition metal composite oxide, wherein the lithium transition metal composite oxide is α-NaFeO _2. Mn and Ni or Mn, Ni and Co as transition metal elements (Me), the molar ratio of Mn to Me is 0.5 <Mn / Me, and the molar ratio of Li to Me The ratio Li / Me is 1 <Li / Me, has an X-ray diffraction pattern that can be assigned to the space group R3-m, and has an Miller index hkl of 104 by X-ray diffraction measurement using Cu-Kα rays (104) The ratio FWHM (003) / FWHM (104) of the half value width (FWHM (003)) of the (003) surface diffraction peak to the half value width (FWHM (104)) of the surface diffraction peak is 0.45 or less, and ( 04) the half-width of the diffraction peak of the plane (FWHM (104)) is the 0.40 ° or more, the positive electrode active material for a nonaqueous electrolyte secondary battery. "Adopted.

  Another aspect of the present invention is “a method for producing a transition metal hydroxide precursor used for producing a positive electrode active material for a non-aqueous electrolyte secondary battery containing a lithium transition metal composite oxide, An alkali solution containing an alkali metal hydroxide, a complexing agent, and a reducing agent of 0.1 to 0.5 M together with a solution containing Mn and Ni or Mn, Ni and Co as transition metal elements (Me) In addition, the pH of the reaction vessel solution is set to 10.5 or less, and a transition metal hydroxide precursor in which the molar ratio of Mn to Me, Mn / Me is 0.5 <Mn / Me, is co-precipitated. It is the manufacturing method of the transition metal hydroxide precursor used for manufacture of the positive electrode active material for nonaqueous electrolyte secondary batteries containing a metal complex oxide. "

According to another aspect of the present invention, “a transition metal hydroxide precursor produced by the above production method and a lithium compound are mixed and fired at 750 to 940 ° C. to form an α-NaFeO ₂ type crystal structure. And a manufacturing method of a positive electrode active material for a non-aqueous electrolyte secondary battery including a lithium transition metal composite oxide having a molar ratio of Li to transition metal (Me) (Li / Me) greater than 1.

  Another aspect of the present invention is a nonaqueous electrolyte secondary battery electrode containing the positive electrode active material, and is a nonaqueous electrolyte secondary battery including the electrode.

  According to the present invention, the initial efficiency of the nonaqueous electrolyte secondary battery can be improved.

1 is an external perspective view showing a nonaqueous electrolyte secondary battery according to one embodiment of the present invention. Schematic showing a power storage device in which a plurality of nonaqueous electrolyte secondary batteries according to one embodiment of the present invention are assembled.

[Positive electrode active material and lithium transition metal composite oxide]
The positive electrode active material for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention (hereinafter referred to as “this embodiment”) is a positive electrode active material containing a lithium transition metal composite oxide.
The composition of the lithium transition metal composite oxide includes Mn and Ni, or a transition metal element Me containing Mn, Ni and Co, and Li, and Li _{1 + α} Me _1-α from the viewpoint of obtaining a high discharge capacity. This is a so-called “lithium-excess type” which can be expressed as O ₂ (α> 0).

In the present embodiment, in the lithium transition metal composite oxide represented by the composition formula Li _{1 + α} Me _1-α O ₂ (α> 0), the transition metal element Me represented by (1 + α) / (1-α) The molar ratio Li / Me to Li is preferably 1.1 or more and less than 1.4, more preferably 1.1 or more and 1.3 or less, and 1.1 or more and 1.2 or less. Is particularly preferred. Within this range, a nonaqueous electrolyte secondary battery with high initial efficiency can be obtained.
The molar ratio Mn / Me of the transition metal element Me is greater than 0.5. 0.51 or more and less than 0.7 is preferable, and 0.51 to 0.60 is more preferable. Within this range, a nonaqueous electrolyte secondary battery with high initial efficiency can be obtained.
Co contained in the lithium transition metal composite oxide has an effect of improving the initial efficiency. However, when there is too much Co, the tap density of the precursor is lowered and the peak differential pore volume is increased. Moreover, since it is a scarce resource, it is expensive. Therefore, the molar ratio Co / Me of Co to the transition metal element Me is preferably 0.20 or less, and may be 0.
The molar ratio Ni / Me of Ni with respect to the transition metal element Me is preferably 0.2 to 0.5, and more preferably 0.25 to 0.4. Within this range, the tap density of the hydroxide precursor can be improved and the discharge capacity per volume is improved.
By using the lithium transition metal composite oxide having the above composition, a non-aqueous electrolyte secondary battery with high initial efficiency can be obtained.

The lithium transition metal composite oxide according to the present embodiment preferably further contains a Ru, Te, Ce, Ta, or S element in addition to the lithium and the transition metal element. When the lithium transition metal composite oxide contains these elements, the initial efficiency of the nonaqueous electrolyte secondary battery when used as the positive electrode active material is improved.
The content of the Ru, Te, Ce, Ta or S element is not particularly limited, but considering the effect of improving the initial efficiency due to the increase in content and the increase in raw material costs, the total amount of Ni, Co and Mn It is preferable to set it as 1-10 mol% with respect to it, and it is more preferable to set it as 1-7 mol%.

  In addition to the above elements, the lithium transition metal composite oxide according to this embodiment is an alkali metal such as Na and K, an alkaline earth metal such as Mg and Ca, Cr, Zn, and the like as long as the effects of the present invention are not impaired. A small amount of other metals such as transition metals represented by 3d transition metals can be contained.

The lithium transition metal composite oxide according to this embodiment has an α-NaFeO ₂ structure. The lithium transition metal composite oxide after synthesis (before charging and discharging) is attributed to the space group P3 ₁ 12 or R3-m. Among these, those belonging to the space group P3 ₁ 12 are superlattice peaks (Li [Li _1/3 Mn _2/3 ] O ₂ near 2θ = 21 ° on the X-ray diffraction diagram using the CuKα tube. The peak observed in the monoclinic type) is confirmed. However, when charging is performed once and Li in the crystal is desorbed, the symmetry of the crystal changes, whereby the superlattice peak disappears and the lithium transition metal composite oxide belongs to the space group R3-m. Will come to be. Here, P3 ₁ 12 is a crystal structure model in which the atomic positions of the 3a, 3b, and 6c sites in R3-m are subdivided, and when ordering is recognized in the atomic arrangement in R3-m, the P3 ₁ 12 model Is adopted. Note that “R3-m” is originally written by adding a bar “-” on “3” of “R3m”.

When the space group R3-m is used as a crystal structure model based on the X-ray diffraction pattern, the lithium transition metal composite oxide according to the present embodiment is (003) relative to the half-value width of the diffraction peak attributed to the (104) plane. ) The ratio of the half width of the diffraction peak attributed to the plane, that is, the value of FWHM (003) / FWHM (104) is 0.45 or less. This value is preferably 0.43 or less.
The diffraction peak at 2θ = 18.6 ° ± 1 ° is indexed to the (003) plane at the Miller index hkl in the space groups P3 ₁ 12 and R3-m, and the diffraction at 2θ = 44.1 ° ± 1 °. peaks, the space group _P3 1 12 (114) plane, is indexed to the space group R3-m (104) plane. Therefore, for the part belonging to the space group P3 ₁ 12, the part described as (104) in this specification is read as (114).

The FWMH ratio is an index of crystallinity along the c-axis direction with respect to crystallinity from all directions in the crystal structure. A small FWHM (003) / FWHM (104) means that the degree of crystal growth in the c-axis direction is large. In this case, Li ions are smoothly inserted and removed from the interlayer, and the initial efficiency of the battery is improved.
The lower limit of FWHM (003) / FWHM (104) is not particularly limited, but is preferably 0.35 or more from the viewpoint of suppressing elution of Mn due to an increase in the contact area between the crystal grain boundary and the electrolyte.

  In the lithium transition metal composite oxide according to this embodiment, the value of the FWHM (104) is 0.40 ° or more. This value is preferably 0.46 ° or more.

The FWHM (104) is an index of the degree of crystallinity from all directions, and the smaller the value, the more advanced the crystallization. When FWHM (104) is 0.40 ° or more, crystallization does not proceed excessively and crystallites are not enlarged, so that Li ions are sufficiently diffused, and the initial efficiency of the battery is improved.
The upper limit of FWHM (104) is not particularly limited, but is preferably 1.00 ° or less, more preferably 0.96 ° or less, and more preferably 0.65 ° or less from the viewpoint of Li ion transport efficiency. It is particularly preferable that

(Measurement of half width)
The half width of the lithium transition metal composite oxide is measured using an X-ray diffractometer (manufactured by Rigaku, model name: MiniFlex II). Specifically, it is performed according to the following conditions and procedures.
The radiation source is CuKα, and the acceleration voltage and current are 30 kV and 15 mA, respectively. The sampling width is 0.01 deg, the scanning time is 14 minutes (scanning speed is 5.0), the divergence slit width is 0.625 deg, the light receiving slit width is open, and the scattering slit is 8.0 mm. With respect to the obtained X-ray diffraction data, the peak derived from Kα2 is not removed, and “PDXL” which is the software attached to the X-ray diffractometer is used to index the (003) plane in the space group R3-m. FWHM (003) for the diffraction peak present at 2θ = 18.6 ± 1 ° on the X-ray diffractogram and present at 2θ = 44 ± 1 ° on the X-ray diffractogram indexed to the (104) plane The half-width FWHM (104) for the diffraction peak to be determined is determined.

If the sample used for the measurement of the half width is an active material powder before electrode preparation, it is used for measurement as it is. When a sample is collected from an electrode taken out by disassembling the battery, the battery is put into a discharged state by the following procedure before disassembling the battery. First, with a current of 0.1 CmA, constant current charging is performed up to a battery voltage at which the positive electrode potential becomes 4.3 V (vs. Li ^/ Li ⁺ ), and at the same battery voltage, the current value decreases to 0.01 CmA. Charge the battery at a constant voltage until the end of charge. After a pause of 30 minutes, constant current discharge is performed at a current of 0.1 CmA until the battery voltage reaches a positive electrode potential of 2.0 V (vs. Li ^/ Li ⁺ ), and a discharge end state is obtained. If the battery uses a metal lithium electrode as the negative electrode, the battery may be disassembled after the battery is brought into the end-of-discharge state or the end-of-charge state, and the electrode may be taken out. In order to accurately control the positive electrode potential, after disassembling the battery and taking out the electrode, after assembling the battery using the metal lithium electrode as a counter electrode, the battery is adjusted to the end of discharge state according to the above procedure.

  The work from disassembly of the battery to measurement is performed in an argon atmosphere with a dew point of −60 ° C. or lower. The taken-out positive electrode plate uses dimethyl carbonate to sufficiently wash the electrolytic solution adhering to the electrode, and after drying at room temperature for a whole day and night, the mixture on the aluminum foil current collector is collected. This mixture is fired at 600 ° C. for 4 hours using a small electric furnace to remove the carbon as the conductive agent and the PVdF binder as the binder, and take out the lithium transition metal composite oxide particles.

In the lithium transition metal composite oxide particles according to the present embodiment, the total pore volume determined by the BJH method from the adsorption isotherm using the nitrogen gas adsorption method is 0.05 cm ³ / g or less. The total pore volume is preferably 0.04 cm ³ / g or less. The peak differential pore volume is preferably 0.2mm ³ / (g · nm) or less, more preferably 0.18mm ³ / (g · nm) or ^{less, 0.12mm 3 / (g · nm} ) or less is particularly preferable. Such a high-density active material can be obtained by firing a high-density transition metal hydroxide precursor and a lithium compound.
By setting the total pore volume of the lithium transition metal composite oxide particles to 0.05 cm ³ / g or less, the discharge capacity per volume can be increased.

(Measurement of total pore volume and peak differential pore volume)
In the present specification, the total pore volume and the peak differential pore volume of the lithium transition metal composite oxide particles are measured by the following method. 1.00 g of the powder of the sample to be measured is placed in a sample tube for measurement and vacuum dried at 120 ° C. for 12 hours to sufficiently remove moisture in the measurement sample. Next, isotherms on the adsorption side and desorption side are measured within a range of relative pressure P / P0 (P0 = about 770 mmHg) from 0 to 1 by a nitrogen gas adsorption method using liquid nitrogen. Then, the pore distribution is evaluated by calculating by the BJH method using the desorption side isotherm, and the peak differential pore volume and the total pore volume are obtained.

The lithium transition metal composite oxide particles according to this embodiment preferably have a tap density of 1.6 g / cm ³ or more, and more preferably 1.7 g / cm ³ or more. By increasing the tap density of the lithium transition metal composite oxide particles, a nonaqueous electrolyte secondary battery having a large discharge capacity per volume can be obtained.

(Measurement of tap density of lithium transition metal composite oxide)
In this specification, the tap density of the lithium transition metal composite oxide is measured by the following method. ² g ± 0.2 g of the powder of the sample to be measured is put into a 10 ⁻² dm ³ graduated cylinder, and REI ELECTRIC CO. LTD. A value obtained by dividing the volume of the sample to be measured after counting 300 times by the input mass using a tapping device manufactured by the company is adopted.

  The positive electrode active material for a non-aqueous electrolyte secondary battery according to the present embodiment may include other positive electrode active materials in addition to the lithium transition metal composite oxide, as long as the effects of the present invention are not impaired. Various forms belong to the technical scope of the present invention.

[Method for producing positive electrode active material (lithium transition metal composite oxide)]
The lithium transition metal composite oxide of this embodiment can be suitably manufactured by a method of firing after mixing a transition metal hydroxide precursor and a lithium compound (Li compound). When the lithium transition metal composite oxide contains Ru, Te, Ce, Ta, or S elements, it is preferable to mix a simple substance or a compound of each element with the coprecipitation precursor and the lithium compound.

The transition metal hydroxide precursor used for producing the lithium transition metal composite oxide includes a transition metal (Me) containing Mn and Ni, or Mn, Ni and Co, and a mole of Mn in the transition metal (Me). The ratio Mn / Me is larger than 0.5, the crystal form is high-density granular, and the tap density is preferably 1.3 g / cm ³ or more, more preferably 1.4 g / cm ³ or more. .
In this specification, the tap density of the hydroxide precursor is measured by the same method as the tap density of the lithium transition metal composite oxide.

Since the lithium transition metal composite oxide according to this embodiment is a “lithium-excess” active material, the molar ratio Mn / Mn of the transition metal element Me in the hydroxide precursor is greater than 0.5. Within this range, it is possible to improve the tap density of the hydroxide precursor.
Further, the molar ratio Co / Me of Co to the transition metal element Me in the hydroxide precursor is preferably 0.2 or less, and may be 0. The molar ratio Ni / Me is preferably 0.2 to 0.5. Within this range, it is possible to improve the tap density of the hydroxide precursor.

When producing the transition metal hydroxide precursor, alkali metal hydroxide (sodium hydroxide, lithium hydroxide, etc.), complexation, together with a solution containing transition metal (Me), in a reaction tank that maintains alkalinity It is preferable to coprecipitate the transition metal hydroxide by adding an alkali solution containing an agent and a reducing agent.
As the complexing agent, ammonia, ammonium sulfate, ammonium nitrate, ammonium fluoride or the like can be used, and ammonia is preferable. A precursor having a higher tap density can be produced by a crystallization reaction using a complexing agent. It is preferable to use a reducing agent together with the complexing agent. As the reducing agent, hydrazine, sodium borohydride and the like can be used, and hydrazine is preferable. Here, sodium hydroxide or lithium hydroxide can be used for the alkali metal hydroxide (neutralizing agent).

  In producing a hydroxide precursor, Mn is easily oxidized among Ni, Co, and Mn, and Ni, Mn, or a coprecipitation precursor in which Ni, Co, and Mn are uniformly distributed in a divalent state is produced. Therefore, uniform mixing at the atomic level of Ni, Mn, or Ni, Co, and Mn tends to be insufficient. In particular, in the composition range of the present embodiment, since the Mn ratio is higher than the Ni and Co ratios, it is particularly important to remove dissolved oxygen in the aqueous solution. Examples of the method for removing dissolved oxygen include a method of bubbling a gas not containing oxygen. The gas not containing oxygen is not limited, but nitrogen gas, argon gas, carbon dioxide (CO2), or the like can be used.

  The pH (reaction tank pH) in the step of producing a hydroxide precursor by coprecipitation of a compound containing Ni, Mn, or Ni, Co, and Mn in the solution is not limited. 14 can be used. In order to increase the tap density, it is preferable to control the pH. The pH is preferably 11.5 or less, more preferably less than 11.0, and particularly preferably 10.5 or less. By co-precipitation at a low pH, the tap density can be increased. Moreover, since the particle growth rate can be accelerated, the stirring continuation time after the raw material aqueous solution dropping is completed can be shortened.

  The raw material of the hydroxide precursor includes manganese oxide, manganese carbonate, manganese sulfate, manganese nitrate, manganese acetate, etc. as the Mn compound, and nickel hydroxide, nickel carbonate, nickel sulfate, nickel nitrate, acetic acid as the Ni compound. Examples of the Co compound such as nickel and the like include cobalt sulfate, cobalt nitrate, and cobalt acetate.

  While the raw material aqueous solution of the hydroxide precursor (aqueous solution containing a transition metal) is supplied dropwise, an alkali metal hydroxide such as sodium hydroxide (neutralizing agent), a complexing agent such as ammonia, hydrazine, etc. A method in which a mixed alkaline solution containing the reducing agent is appropriately dropped is preferable. The concentration of the alkali metal hydroxide to be dropped is preferably 1.0 to 8.0M. The concentration of the complexing agent is preferably 0.05 to 2.0M, and more preferably 0.6 to 1.5M. The concentration of the reducing agent is preferably 0.02 to 1.0M, and more preferably 0.1 to 0.5M.

  The dropping rate of the raw material aqueous solution greatly affects the uniformity of the element distribution within one particle of the hydroxide precursor to be produced. In particular, Mn is difficult to form a uniform element distribution with Ni or Co, so care must be taken. The preferred dropping rate is influenced by the reaction vessel size, stirring conditions, pH, reaction temperature, etc., but is preferably 30 ml / min or less. In order to improve the discharge capacity, the dropping rate is more preferably 10 ml / min or less, and most preferably 5 ml / min or less.

  Further, when a complexing agent such as ammonia is present in the reaction tank and a certain convection condition is applied, the particles are rotated and revolved in the stirring tank by continuing the stirring after the dropwise addition of the raw material aqueous solution. In this process, particles collide with each other, and the particles grow concentrically in stages. That is, the hydroxide precursor undergoes two stages of reaction: a metal complex formation reaction when the raw material aqueous solution is dropped into the reaction tank, and a precipitation formation reaction that occurs while the metal complex is retained in the reaction tank. Formed through. Therefore, a hydroxide precursor having a target particle diameter can be obtained by appropriately selecting a time for continuing stirring after the dropping of the raw material aqueous solution.

  The preferable stirring duration after completion of dropping of the raw material aqueous solution is influenced by the size of the reaction vessel, stirring conditions, pH, reaction temperature, etc., but 0.5 h or more is required to grow the particles as uniform spherical particles. Preferably, 1 h or more is more preferable. Further, in order to reduce the possibility that the output performance in the low SOC region of the battery is not sufficient due to the particle size becoming too large, it is preferably 15 h or less, more preferably 10 h or less, and most preferably 5 h or less.

  Moreover, the preferable stirring duration time for making the particle size of the secondary particles of the hydroxide precursor and the lithium transition metal composite oxide suitable depends on the pH to be controlled. For example, when the pH is controlled to 8 to 14, the stirring duration is preferably 0.5 to 5 h, and when the pH is controlled to 9 to 10, the stirring duration is preferably 1 to 3 h.

  When the hydroxide precursor particles are produced using a sodium compound such as sodium hydroxide as a neutralizing agent, sodium ions adhering to the particles are removed by washing in a subsequent washing step. For example, when the produced hydroxide precursor is removed by suction filtration, a condition that the number of washings with 100 ml of ion-exchanged water is 5 times or more can be employed.

  As the Li compound to be mixed with the hydroxide precursor, lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, or the like can be used. However, with respect to the amount of the Li compound, it is preferable to add an excess of about 1 to 5% in view of the disappearance of a part of the Li compound during firing.

Examples of Ru, Te, Ce, Ta or S mixed with the hydroxide precursor and the Li compound include Ru, RuO ₂ , RuF ₆ , RuCl ₃ , Te, TeO ₂ , TeO ₃ , TeCl ₄ , Li ₂ TeO ₃ , CeO ₂ , CeSO ₄ .5H ₂ O, Ce ₂ (CO ₃ ) ₃ , Ce (NO ₃ ) ₃ , Ce (OH) ₄ , Ce ₂ O ₃ , CeCl ₃ , CeF ₃ , Ce ₂ S ₃ , Ta, Ta ₂ O ₅ , TaO, TaO ₂ , TaS ₂ , TaBr ₅ , S and the like can be used.

The temperature at which the mixture of the transition metal hydroxide precursor and the Li compound, or the mixture further containing a simple substance or compound of Ru, Te, Ce, Ta, or S, or the compound further affects the reversible capacity of the active material.
When the firing temperature is too high, the obtained active material collapses with an oxygen releasing reaction, and in addition to the hexagonal crystal of the main phase, the monoclinic Li [Li _1/3 Mn _2/3 ] O ₂ type is obtained. The defined phase tends to be observed as a phase separation rather than as a solid solution phase. If too many such phase separations are contained, it is not preferable because it leads to a reduction in the reversible capacity of the active material. In such materials, impurity peaks are observed around 35 ° and 45 ° on the X-ray diffraction pattern. Therefore, the firing temperature is preferably less than the temperature at which the oxygen release reaction of the active material affects. The oxygen release temperature of the active material is approximately 1000 ° C. or higher in the composition range according to the present embodiment, but there is a slight difference in the oxygen release temperature depending on the composition of the active material. It is preferable to confirm. In particular, it is confirmed that the oxygen release temperature of the hydroxide precursor shifts to a lower temperature side as the amount of Co contained in the sample increases. As a method for confirming the oxygen release temperature of the active material, a mixture of a hydroxide precursor and a lithium compound may be subjected to thermogravimetric analysis (DTA-TG measurement) in order to simulate the firing reaction process. However, in this method, the platinum used in the sample chamber of the measuring instrument may be corroded by the Li component volatilized, and the instrument may be damaged, so a crystallization temperature is advanced to some extent by adopting a firing temperature of about 500 ° C. in advance. The composition may be subjected to thermogravimetric analysis.

On the other hand, if the firing temperature is too low, crystallization does not proceed sufficiently and the electrode characteristics tend to deteriorate. In the present embodiment, the firing temperature is preferably higher than 700 ° C. By sufficiently crystallizing, the resistance of the crystal grain boundary can be reduced and smooth lithium ion transport can be promoted.
In addition, the inventors have analyzed the half width of the diffraction peak of the active material according to this embodiment in detail, and in the sample synthesized at a temperature up to 750 ° C., strain remains in the lattice, and more It was confirmed that most of the strain could be removed by synthesizing at the temperature of. The crystallite size was increased in proportion to the increase in the synthesis temperature. Therefore, even in the composition of the active material according to the present embodiment, a favorable discharge capacity can be obtained by aiming at a particle having almost no lattice distortion in the system and having a sufficiently grown crystallite size. Specifically, it is preferable to employ a synthesis temperature (firing temperature) and a Li / Me ratio composition in which the strain amount affecting the lattice constant is 2% or less and the crystallite size is grown to 50 nm or more. all right. Although changes due to expansion and contraction can be observed by charging and discharging by forming these as electrodes, it is preferable as an effect that the crystallite size is maintained at 30 nm or more in the charging and discharging process. That is, an active material having a remarkably large reversible capacity can be obtained only by selecting the firing temperature as close as possible to the oxygen release temperature of the active material.

As described above, since the preferable firing temperature varies depending on the oxygen release temperature of the active material, it is difficult to generally set a preferable range of the firing temperature, but the molar ratio Li / Me is 1.1 to 1.3. In this case, the firing temperature is preferably 750 to 940 ° C., more preferably 750 to 900 ° C., in order to make the discharge capacity per volume sufficient.
As described above, the lithium transition metal composite oxide used as the positive electrode active material of the present embodiment is manufactured.

As described above, the lithium transition metal composite oxide used as the positive electrode active material of the present embodiment is manufactured.
The lithium transition metal composite oxide produced by this method has an α-NaFeO ₂ type crystal structure, and the molar ratio of Li and transition metal (Me) constituting the lithium transition metal composite oxide (Li / Me) Is greater than 1, the transition metal (Me) contains Mn and Ni, or Mn, Ni and Co, and the molar ratio of Mn in the transition metal (Me) Mn / Me is greater than 0.5.

[Negative electrode active material]
The negative electrode active material is not limited. Any form that can deposit or occlude lithium ions may be selected. For example, titanium-based materials such as lithium titanate having a spinel crystal structure represented by Li [Li _1/3 Ti _5/3 ] O ₄ , alloy-based materials such as Si, Sb, and Sn-based lithium metal, lithium alloys (Lithium metal-containing alloys such as lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloys), lithium composite oxide (lithium-titanium), silicon oxide In addition, an alloy capable of inserting and extracting lithium, a carbon material (for example, graphite, hard carbon, low-temperature fired carbon, amorphous carbon, etc.) can be used.

  The positive electrode active material powder and the negative electrode active material powder preferably have an average particle size of 100 μm or less. In particular, the powder of the positive electrode active material is preferably 15 μm or less for the purpose of improving the high output characteristics of the nonaqueous electrolyte secondary battery. In order to obtain the powder in a predetermined shape, there are a method for producing a precursor having a predetermined size, a method using a pulverizer, a classifier, and the like. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling air flow type jet mill, a sieve, or the like is used. At the time of pulverization, wet pulverization in the presence of water or an organic solvent such as hexane may be used. There is no particular limitation on the classification method, and a sieve, an air classifier, or the like is used as needed for both dry and wet methods.

[Other electrode components]
As described above, the positive electrode active material and the negative electrode active material which are main components of the positive electrode and the negative electrode have been described in detail. In addition to the main component, the positive electrode and the negative electrode include a conductive agent, a binder, a thickener, A filler etc. may be contained as another structural component.

  The conductive agent is not limited as long as it is an electron conductive material that does not adversely affect the battery performance. Usually, natural graphite (such as scaly graphite, scaly graphite, earthy graphite), artificial graphite, carbon black, acetylene black, Conductive materials such as ketjen black, carbon whisker, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.) powder, metal fiber, and conductive ceramic material can be included as one kind or a mixture thereof. .

  Among these, as the conductive agent, acetylene black is preferable from the viewpoints of electron conductivity and coatability. The addition amount of the conductive agent is preferably 0.1% by weight to 50% by weight, and particularly preferably 0.5% by weight to 30% by weight with respect to the total weight of the positive electrode or the negative electrode. In particular, acetylene black is preferably used after being pulverized into ultrafine particles of 0.1 to 0.5 μm because the required carbon amount can be reduced. These mixing methods are physical mixing, and the ideal is uniform mixing. Therefore, powder mixers such as V-type mixers, S-type mixers, crackers, ball mills, and planetary ball mills can be mixed dry or wet.

  The binder is usually a thermoplastic resin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene. Polymers having rubber elasticity such as rubber (SBR) and fluororubber can be used as one kind or a mixture of two or more kinds. The addition amount of the binder is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight, based on the total weight of the positive electrode or the negative electrode.

  As the filler, any material that does not adversely affect the battery performance may be used. Usually, olefin polymers such as polypropylene and polyethylene, amorphous silica, alumina, zeolite, glass, carbon and the like are used. The addition amount of the filler is preferably 30% by weight or less with respect to the total weight of the positive electrode or the negative electrode.

[Production of positive electrode and negative electrode]
The positive electrode and the negative electrode are prepared by mixing the main constituents (positive electrode active material in the positive electrode, negative electrode material in the negative electrode) and other materials into a mixture and mixing with an organic solvent such as N-methylpyrrolidone or toluene or water. After that, the obtained liquid mixture is applied on a current collector described in detail below, or pressed and heat-treated at a temperature of about 50 ° C. to 250 ° C. for about 2 hours. . About the application method, for example, it is desirable to apply to any thickness and any shape using means such as roller coating such as applicator roll, screen coating, doctor blade method, spin coating, bar coater, etc. It is not limited.

  As the current collector, a current collector foil such as an Al foil or a Cu foil can be used. The positive electrode current collector foil is preferably an Al foil, and the negative electrode current collector foil is preferably a Cu foil. The thickness of the current collector foil is preferably 10 to 30 μm. Further, the thickness of the mixture layer is preferably 40 to 150 μm (excluding the current collector foil thickness) after pressing.

[Nonaqueous electrolyte]
The nonaqueous electrolyte used for the nonaqueous electrolyte secondary battery according to the present embodiment is not limited, and those generally proposed for use in lithium batteries and the like can be used. Nonaqueous solvents used for the nonaqueous electrolyte include cyclic carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate and vinylene carbonate; cyclic esters such as γ-butyrolactone and γ-valerolactone; dimethyl carbonate, Chain carbonates such as diethyl carbonate and ethyl methyl carbonate; chain esters such as methyl formate, methyl acetate and methyl butyrate; tetrahydrofuran or derivatives thereof; 1,3-dioxane, 1,4-dioxane, 1,2-dimethoxy Ethers such as ethane, 1,4-dibutoxyethane and methyldiglyme; Nitriles such as acetonitrile and benzonitrile; Dioxolane or derivatives thereof; Ethylene sulfide, sulfolane, sultone or derivatives thereof Examples thereof include a conductor alone or a mixture of two or more thereof, but are not limited thereto.

Examples of the electrolyte salt used for the non-aqueous electrolyte include LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiSCN, LiBr, LiI, Li ₂ SO ₄ , Li ₂ B ₁₀ Cl ₁₀ , NaClO ₄ , NaI, NaSCN, NaBr , KClO ₄ , KSCN, and other inorganic ion salts containing one of lithium (Li), sodium (Na), or potassium (K), LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ (SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , (CH ₃ ) ₄ NBF ₄ , ( CH ₃ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NI, (C ₃ H ₇ ) ₄ NBr, (n-C ₄ H ₉ ) ₄ NClO ₄ , (nC ₄ H ₉ ) ₄ NI, (C ₂ H ₅ ) ₄ N-maleate, (C ₂ H ₅ ) ₄ N-benzoate, (C ₂ H ₅ ) ₄ N-phthalate, Examples thereof include organic ionic salts such as lithium stearyl sulfonate, lithium octyl sulfonate, and lithium dodecylbenzene sulfonate. These ionic compounds can be used alone or in admixture of two or more.

Further, by using a mixture of LiPF ₆ or LiBF ₄ and a lithium salt having a perfluoroalkyl group such as LiN (C ₂ F ₅ SO ₂ ) ₂ , the viscosity of the electrolyte can be further reduced, Low temperature characteristics can be further improved, and self-discharge can be suppressed, which is more preferable.
Moreover, you may use normal temperature molten salt and an ionic liquid as a nonaqueous electrolyte.

  The concentration of the electrolyte salt in the nonaqueous electrolyte is preferably 0.1 mol / l to 5 mol / l, more preferably 0.5 mol / l in order to reliably obtain a nonaqueous electrolyte secondary battery having high battery characteristics. -2.5 mol / l.

[Separator]
As the separator, it is preferable to use a porous film or a non-woven fabric exhibiting excellent high rate discharge performance alone or in combination. Examples of the material constituting the separator for nonaqueous electrolyte secondary batteries include polyolefin resins typified by polyethylene, polypropylene, etc., polyester resins typified by polyethylene terephthalate, polybutylene terephthalate, etc., polyvinylidene fluoride, vinylidene fluoride, etc. -Hexafluoropropylene copolymer, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-fluoroethylene copolymer , Vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-propylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinyl fluoride Den - tetrafluoroethylene - hexafluoropropylene copolymer, vinylidene fluoride - ethylene - can be mentioned tetrafluoroethylene copolymer.

  The porosity of the separator is preferably 98% by volume or less from the viewpoint of strength. Further, the porosity is preferably 20% by volume or more from the viewpoint of charge / discharge characteristics.

  The separator may be a polymer gel composed of a polymer such as acrylonitrile, ethylene oxide, propylene oxide, methyl methacrylate, vinyl acetate, vinyl pyrrolidone, polyvinylidene fluoride, and an electrolyte. Use of the non-aqueous electrolyte in the gel state as described above is preferable in that it has an effect of preventing leakage.

  Furthermore, it is preferable to use a separator in combination with the above-described porous film, non-woven fabric, or the like and a polymer gel because the liquid retention of the electrolyte is improved. That is, by forming a film in which the surface of the polyethylene microporous membrane and the microporous wall are coated with a solvophilic polymer having a thickness of several μm or less, and holding the electrolyte in the micropores of the film, Gels.

  Examples of the solvophilic polymer include polyvinylidene fluoride, an acrylate monomer having an ethylene oxide group or an ester group, an epoxy monomer, a polymer having a monomer having an isocyanate group, and the like crosslinked. The monomer can be subjected to a crosslinking reaction by irradiation with an electron beam (EB) or heating or ultraviolet (UV) irradiation with a radical initiator added.

[Configuration of non-aqueous electrolyte secondary battery]
The configuration of the nonaqueous electrolyte secondary battery according to the present embodiment is not particularly limited, and a cylindrical battery, a square battery (rectangular battery), and a flat battery having a positive electrode, a negative electrode, and a roll separator. Etc. are mentioned as an example.
FIG. 1 shows an external perspective view of a rectangular nonaqueous electrolyte secondary battery 1 which is a nonaqueous electrolyte secondary battery according to one embodiment of the present invention. In the figure, the inside of the container is seen through. In the nonaqueous electrolyte secondary battery 1 shown in FIG. 1, an electrode group 2 is housed in a battery container 3. The electrode group 2 is formed by winding a positive electrode including a positive electrode active material and a negative electrode including a negative electrode active material via a separator. The positive electrode is electrically connected to the positive electrode terminal 4 via the positive electrode lead 4 ′, and the negative electrode is electrically connected to the negative electrode terminal 5 via the negative electrode lead 5 ′.

[Configuration of power storage device]
This embodiment can also be realized as a power storage device in which a plurality of the nonaqueous electrolyte secondary batteries are assembled. A power storage device according to one embodiment of the present invention is illustrated in FIG. In FIG. 2, the power storage device 30 includes a plurality of power storage units 20. Each power storage unit 20 includes a plurality of nonaqueous electrolyte secondary batteries 1. The power storage device 30 can be mounted as a power source for vehicles such as an electric vehicle (EV), a hybrid vehicle (HEV), and a plug-in hybrid vehicle (PHEV).

(Example 1)
<Production process of hydroxide precursor>
A hydroxide precursor was prepared by the following procedure using the reaction crystallization method. First, 315.4 g of nickel sulfate hexahydrate, 168.6 g of cobalt sulfate heptahydrate, and 530.4 g of manganese sulfate pentahydrate were weighed and dissolved in 4 L of ion-exchanged water. A 1.0 M aqueous sulfate solution having a Co: Mn molar ratio of 30:15:55 was prepared. Next, 2 L of ion exchange water was poured into a 5 L reaction vessel, and nitrogen gas was bubbled for 30 minutes to remove oxygen contained in the ion exchange water. The reaction vessel temperature is set to 50 ° C. (± 2 ° C.), and the reaction vessel is stirred at a rotational speed of 1500 rpm using a paddle blade equipped with a stirring motor so that sufficient convection occurs in the reaction layer. did. The sulfate stock solution was dropped into the reaction vessel at a rate of 1.3 ml / min for 50 hr. Here, during the period from the start to the end of the dropping, a mixed alkali solution composed of 4.0 M sodium hydroxide, 0.6 M ammonia, and 0.3 M hydrazine is appropriately dropped to adjust the pH in the reaction vessel. Control was performed to always maintain 9.55 (± 0.1), and a part of the reaction solution was discharged by overflow, so that the total amount of the reaction solution was always controlled not to exceed 2 L. After completion of the dropwise addition, stirring in the reaction vessel was continued for 1 hour. After stopping stirring, the mixture was allowed to stand at room temperature for 12 hours or longer.
Next, using a suction filtration device, the hydroxide precursor particles generated in the reaction tank are separated, and further, sodium ions adhering to the particles are washed and removed using ion exchange water, and an electric furnace is used. Then, it was dried in an air atmosphere at 80 ° C. under normal pressure for 20 hours. Then, in order to arrange | equalize a particle size, it grind | pulverized for several minutes with the smoked automatic mortar. In this way, a hydroxide precursor was produced.

<Baking process>
1.278 g of lithium hydroxide monohydrate and 0.112 g of ruthenium dioxide are added to 2.168 g of the hydroxide precursor and mixed well using a smoked automatic mortar, and Li: (Ni, Co, A mixed powder having a molar ratio of Mn, Ru) of 120: 100 and a molar ratio of (Ni, Co, Mn): Ru of 100: 3 was prepared. Using a pellet molding machine, molding was performed at a pressure of 6 MPa to obtain pellets having a diameter of 25 mm. The amount of the mixed powder subjected to pellet molding was determined by conversion so that the mass of the assumed final product was 2.5 g. One pellet was placed on an alumina boat having a total length of about 100 mm, placed in a box-type electric furnace (model number: AMF20), heated in air atmosphere at normal pressure from room temperature to 800 ° C. over 10 hours, Baked at 800 ° C. for 4 h. The box-type electric furnace has internal dimensions of 10 cm in length, 20 cm in width, and 30 cm in depth, and heating wires are inserted at intervals of 20 cm in the width direction. After firing, the heater was turned off and allowed to cool naturally with the alumina boat placed in the furnace. As a result, the temperature of the furnace decreases to about 200 ° C. after 5 hours, but the subsequent temperature decrease rate is somewhat moderate. After the passage of day and night, it was confirmed that the furnace temperature was 100 ° C. or lower, and then the pellets were taken out and pulverized for several minutes in a smoked automatic mortar in order to make the particle diameter uniform. In this way, a lithium transition metal composite oxide according to Example 1 was produced.

(Example 2)
In the firing step, 1.294 g of lithium hydroxide monohydrate and 0.158 g of lithium tellurite are added to 2.262 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn) is increased. The lithium transition metal composite oxidation according to Example 2 was performed in the same manner as in Example 1 except that a mixed powder having a molar ratio of 120: 100 and (Ni, Co, Mn): Te of 100: 3 was prepared. A product was made.

(Example 3)
In the firing step, 1.264 g of lithium hydroxide monohydrate and 0.335 g of cerium sulfate pentahydrate are added to 2.144 g of the hydroxide precursor, and Li: (Ni, Co, Mn, Ce) is added. The lithium according to Example 3 was prepared in the same manner as in Example 1 except that a mixed powder having a molar ratio of 120: 100 and (Ni, Co, Mn): Ce of 100: 3 was prepared. A transition metal composite oxide was produced.

Example 4
In the firing step, 1.249 g of lithium hydroxide monohydrate and 0.182 g of tantalum pentoxide are added to 2.120 g of the hydroxide precursor, and a molar ratio of Li: (Ni, Co, Mn, Ta) is added. Was prepared in the same manner as in Example 1 except that a mixed powder having a molar ratio of (Ni, Co, Mn): Ta of 100: 3 was prepared. An oxide was produced.

(Example 5)
In the firing step, 1.294 g of lithium hydroxide monohydrate and 0.053 g of sulfur are added to 2.262 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn) is 120: 100. , (Ni, Co, Mn): A lithium transition metal composite oxide according to Example 5 was produced in the same manner as in Example 1 except that a mixed powder having a molar ratio of 100: 3 was prepared. did.

(Example 6)
In the firing step, 1.214 g of lithium hydroxide monohydrate is added to 2.315 g of the hydroxide precursor, the molar ratio of Li: (Ni, Co, Mn) is 110: 100, and the additive element is included. A lithium transition metal composite oxide according to Example 6 was produced in the same manner as in Example 1 except that no mixed powder was prepared.

(Example 7)
In the process of preparing the hydroxide precursor, 262.8 g of nickel sulfate hexahydrate, 224.9 g of cobalt sulfate heptahydrate, and 530.4 g of manganese sulfate pentahydrate were weighed, and the total amount of these was ion-exchanged. Dissolve in 4 L of water to prepare a 1.0 M sulfate aqueous solution having a molar ratio of Ni: Co: Mn of 25:20:55. By appropriately dropping a mixed alkaline solution consisting of sodium hydroxide, 1.5M ammonia, and 0.2M hydrazine, the pH in the reaction vessel was controlled so as to always maintain 9.8 (± 0.1). In the firing step, 1.214 g of lithium hydroxide monohydrate is added to 2.315 g of the hydroxide precursor, the molar ratio of Li: (Ni, Co, Mn) is 110: 100, and the additive element Not included The Gokotai was prepared and except that a 900 ° C. firing temperature, in the same manner as in Example 1 to prepare a lithium transition metal composite oxide according to Example 7.

(Example 8)
In the process of preparing the hydroxide precursor, 315.4 g of nickel sulfate hexahydrate, 112.4 g of cobalt sulfate heptahydrate, and 578.6 g of manganese sulfate pentahydrate were weighed, and the total amount of these was ion-exchanged. It was dissolved in 4 L of water to prepare a 1.0 M sulfate aqueous solution having a molar ratio of Ni: Co: Mn of 30:10:60. In the firing step, 2.262 g of the hydroxide precursor was added with water. Except that 1.297 g of lithium oxide monohydrate was added and a mixed powder containing Li: (Ni, Co, Mn) at a molar ratio of 120: 100 and containing no additional elements was prepared, the same as in Example 1. Thus, a lithium transition metal composite oxide according to Example 8 was produced.

Example 9
In the process of preparing the hydroxide precursor, 420.6 g of nickel sulfate hexahydrate, 56.2 g of cobalt sulfate heptahydrate, and 530.4 g of manganese sulfate pentahydrate were weighed, and the total amount of these was ion-exchanged. Dissolve in 4 L of water to prepare a 1.0 M sulfate aqueous solution having a molar ratio of Ni: Co: Mn of 40: 5: 55. By appropriately dropping a mixed alkaline solution consisting of sodium hydroxide, 1.5M ammonia, and 0.5M hydrazine, the pH in the reaction vessel was controlled so as to always maintain 9.7 (± 0.1). In the firing step, 1.214 g of lithium hydroxide monohydrate is added to 2.315 g of the hydroxide precursor, the molar ratio of Li: (Ni, Co, Mn) is 110: 100, and the additive element Does not contain Except that to prepare a body, in the same manner as in Example 1 to prepare a lithium transition metal composite oxide according to Example 9.

(Example 10)
In the step of preparing the hydroxide precursor, 473.1 g of nickel sulfate hexahydrate and 530.4 g of manganese sulfate pentahydrate were weighed, and all of these were dissolved in 4 L of ion-exchanged water, and Ni: Co: A 1.0 M aqueous sulfate solution having a Mn molar ratio of 45: 0: 55 was prepared, and 4.0 M sodium hydroxide, 1.25 M ammonia, from the start to the end of the addition of the aqueous sulfate solution, In addition, in the firing step, the hydroxide was controlled so that the pH in the reaction tank was always maintained at 10.2 (± 0.1) by appropriately dropping a mixed alkaline solution composed of 0.4 M hydrazine. Lithium hydroxide monohydrate 1.209g and ruthenium dioxide 0.112g are added to the precursor 2.283g, and the molar ratio of Li: (Ni, Co, Mn, Ru) is 110: 100, (Ni, Co Mn): molar ratio of Ru is 100: except that prepared mixed powder is 3, in the same manner as in Example 1 to prepare a lithium transition metal composite oxides according to Example 10.

(Comparative Example 1)
In the firing step, 1.294 g of lithium hydroxide monohydrate is added to 2.262 g of the hydroxide precursor, the molar ratio of Li: (Ni, Co, Mn) is 120: 100, and the additive element is included. A lithium transition metal composite oxide according to Comparative Example 1 was produced in the same manner as in Example 1 except that no mixed powder was prepared.

(Comparative Example 2)
In the firing step, 1.32 g of lithium hydroxide monohydrate and 0.021 g of beryllium oxide are added to 2.227 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn, Be) is increased. Lithium transition metal composite oxidation according to Comparative Example 2 in the same manner as in Example 1, except that a mixed powder having a molar ratio of 120: 100 and (Ni, Co, Mn): Be of 100: 3 was prepared. A product was made.

(Comparative Example 3)
In the firing step, 1.219 g of lithium hydroxide monohydrate and 0.379 g of lithium iodide are added to 2.262 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn) is 120. : 100, (Ni, Co, Mn): The lithium transition metal composite oxide according to Comparative Example 3 is the same as Example 1 except that a mixed powder having a molar ratio of 100: 3 is prepared. Was made.

(Comparative Example 4)
In the firing step, 1.301 g of lithium hydroxide monohydrate and 0.057 g of potassium carbonate are added to 2.208 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn, K) is 120. : 100, (Ni, Co, Mn): Lithium transition metal composite oxide according to Comparative Example 4 as in Example 1 except that a mixed powder having a molar ratio of 100: 3 was prepared. Was made.

(Comparative Example 5)
In the firing step, 1.300 g of lithium hydroxide monohydrate and 0.063 g of calcium hydroxide are added to 2.207 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn, Ca) is increased. Was prepared in the same manner as in Example 1 except that a mixed powder having a molar ratio of (Ni, Co, Mn): Ca of 100: 3 was prepared. An oxide was produced.

(Comparative Example 6)
In the calcination step, 1.239 g of lithium hydroxide monohydrate and 0.192 g of dibismuth trioxide are added to 2.103 g of the hydroxide precursor, and the moles of Li: (Ni, Co, Mn, Bi) are added. A lithium transition metal according to Comparative Example 6 in the same manner as in Example 1 except that a mixed powder having a ratio of 120: 100 and (Ni, Co, Mn): Bi of 100: 3 was prepared. A composite oxide was produced.

(Comparative Example 7)
In the firing step, 1.371 g of lithium hydroxide monohydrate is added to 2.212 g of the hydroxide precursor, the molar ratio of Li: (Ni, Co, Mn) is 130: 100, and no additional elements are contained. A lithium-transition metal composite oxide according to Comparative Example 7 was produced in the same manner as in Example 1 except that a mixed powder was prepared and the firing temperature was 900 ° C.

(Comparative Example 8)
In the firing step, 1.093 g of lithium hydroxide monohydrate and 0.075 g of lithium fluoride are added to 2.315 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn) is 120. : 100, a lithium transition metal composite oxide according to Comparative Example 8 was produced in the same manner as in Example 1 except that a mixed powder containing no additive element was prepared.

(Confirmation of α-NaFeO type ₂ crystal structure)
It was confirmed that the lithium transition metal composite oxides according to Examples 1 to 10 and Comparative Examples 1 to 8 had an α-NaFeO ₂ type crystal structure because the structural model and the diffraction pattern in the X-ray diffraction measurement coincided. .

(Measurement of half width)
The half widths of the lithium transition metal composite oxides according to Examples 1 to 10 and Comparative Examples 1 to 8 are measured using an X-ray diffractometer (manufactured by Rigaku, model name: MiniFlex II) according to the above-described conditions and procedures. Went. A diffraction peak existing at 2θ = 18.6 ° ± 1 ° on the X-ray diffractogram, indexed to the (003) plane in the space group R3-m, using “PDXL” which is software attached to the X-ray diffractometer. FWHM (003) and FWHM (104) for the diffraction peak at 2θ = 44 ± 1 ° on the X-ray diffractogram indexed to the (104) plane. From the measurement result, FWHM (003) / FWHM (104) was obtained.

[Preparation of electrode for non-aqueous electrolyte secondary battery]
Using the lithium transition metal composite oxides according to Examples 1 to 10 and Comparative Examples 1 to 8 as positive electrode active materials, respectively, the non-aqueous electrolyte secondary according to Examples 1 to 10 and Comparative Examples 1 to 8 in the following procedure A battery electrode was prepared.

  Using N-methylpyrrolidone as a dispersion medium, an active material, acetylene black (AB), and polyvinylidene fluoride (PVdF) were kneaded and dispersed at a mass ratio of 90: 5: 5. The coating paste was applied to one side of an aluminum foil current collector having a thickness of 20 μm to produce a positive electrode plate. In addition, the application thickness of the active material applied per fixed area is standardized so that the test conditions for determining the discharge capacity per volume between the nonaqueous electrolyte secondary batteries according to all Examples and Comparative Examples are the same. did. A part of the electrode for a nonaqueous electrolyte secondary battery produced in this way was cut out, a nonaqueous electrolyte secondary battery (lithium secondary battery) was produced by the following procedure, and the battery characteristics were evaluated.

[Production and evaluation of nonaqueous electrolyte secondary battery]
For the purpose of accurately observing the single behavior of the positive electrode, metallic lithium was used in close contact with the nickel foil current collector for the counter electrode, that is, the negative electrode. Here, a sufficient amount of metallic lithium was disposed on the negative electrode so that the capacity of the nonaqueous electrolyte secondary battery was not limited by the negative electrode.

As an electrolytic solution, LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC) had a volume ratio of 6: 7: 7 so that the concentration was 1 mol / l. The solution was used. As the separator, a polypropylene microporous film whose surface was modified with polyacrylate was used. A metal resin composite film made of polyethylene terephthalate (15 μm) / aluminum foil (50 μm) / metal-adhesive polypropylene film (50 μm) was used for the outer package. The electrode is housed so that the open ends of the positive electrode terminal and the negative electrode terminal are exposed to the outside, and the fusion margin where the inner surfaces of the metal resin composite film face each other is hermetically sealed except for the portion serving as a liquid injection hole, After injecting the electrolytic solution, the injection hole was sealed.

  The nonaqueous electrolyte secondary battery produced by the above procedure was subjected to an initial charge / discharge process at 25 ° C. Charging was carried out at a constant current and constant voltage with a current of 0.1 CmA and a voltage of 4.6 V, and the charge termination condition was the time when the current value attenuated to 1/5. The discharge was a constant current discharge with a current of 0.1 CmA and a final voltage of 2.0 V. This charge / discharge was performed for two cycles. Here, a pause process of 10 minutes was provided after charging and discharging, respectively. The percentage indicated by “(discharged electric quantity) / (charged electric quantity) × 100” in the first cycle in the initial charge / discharge process was recorded as “initial efficiency (%)”.

  Ni / Co / Mn molar ratio, Li / Me ratio, firing temperature, type and amount of additive element, FWHM (003) / of lithium transition metal composite oxides according to Examples 1 to 10 and Comparative Examples 1 to 8 Table 1 shows the initial efficiencies of the nonaqueous electrolyte secondary battery using FWHM (104), FWHM (104), and the lithium transition metal composite oxide as positive electrode active materials.

From Table 1, have the alpha-NaFeO ₂ structure, as the transition metal (Me), includes Ni and Mn, or Ni, Co and Mn, with Li / Me> 1, a Mn / Me> 0.5, Nonaqueous electrolyte secondary using lithium transition metal composite oxides according to Examples 1 to 10 where FWHM (003) / FWHM (104) is 0.45 or less and FWHM (104) is 0.40 ° or more It can be seen that the battery has a high initial efficiency.

  On the other hand, when FWHM (003) / FWHM (104) of the lithium transition metal composite oxide exceeds 0.45, as in Comparative Examples 1-6, 8, or lithium transition metal, as in Comparative Examples 6-8 When the FWHM (104) of the composite oxide is less than 0.40 °, the initial efficiency of the nonaqueous electrolyte secondary battery using this is low.

As described above, it has an α-NaFeO ₂ structure, includes Ni and Mn, or Ni, Co, and Mn as transition metals (Me), Li / Me> 1, and Mn / Me> 0.5 A lithium transition metal composite oxide satisfying the requirement that FWHM (003) / FWHM (104) is 0.45 or less and FWHM (104) is 0.40 ° or more is used for a non-aqueous electrolyte secondary battery. By using it as a positive electrode active material, a nonaqueous electrolyte secondary battery with high initial efficiency can be provided.

  By using a positive electrode active material containing a lithium transition metal composite oxide according to one aspect of the present invention, a non-aqueous electrolyte secondary battery with high initial efficiency can be provided. It is useful as a non-aqueous electrolyte secondary battery for hybrid vehicles and electric vehicles.

1 Nonaqueous electrolyte secondary battery (lithium secondary battery)
2 Electrode group 3 Battery container 4 Positive electrode terminal 4 ′ Positive electrode lead 5 Negative electrode terminal 5 ′ Negative electrode lead 20 Power storage unit 30 Power storage device

Claims (7)

An active material for a non-aqueous electrolyte secondary battery containing a lithium transition metal composite oxide,
The lithium transition metal composite oxide is
having an α-NaFeO ₂ structure,
Mn and Ni or Mn, Ni and Co as transition metal elements (Me)
The molar ratio of Mn to Me, Mn / Me is 0.5 <Mn / Me,
The molar ratio of Li to Me Li / Me is 1 <Li / Me,
Having an X-ray diffraction pattern that can be assigned to the space group R3-m;
X-ray diffraction measurement using Cu-Kα rays, the half-value width (FWHM (003)) of the (003) plane diffraction peak with respect to the half-width (FWHM (104)) of the (104) plane diffraction peak at the Miller index hkl The ratio FWHM (003) / FWHM (104) is 0.45 or less,
The half-value width (FWHM (104)) of the diffraction peak of the (104) plane is 0.40 ° or more.
Positive electrode active material for non-aqueous electrolyte secondary battery.   The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium transition metal composite oxide contains a Ru, Te, Ce, Ta, or S element. A method for producing a transition metal hydroxide precursor used for producing a positive electrode active material for a non-aqueous electrolyte secondary battery containing a lithium transition metal composite oxide,
The reaction vessel contains Mn and Ni as a transition metal element (Me) or a solution containing Mn, Ni and Co, as well as an alkali metal hydroxide, a complexing agent, and a 0.1 to 0.5M reducing agent. The transition metal hydroxide precursor in which the molar ratio of Mn to Me, Mn / Me is 0.5 <Mn / Me, is coprecipitated by adding an alkaline solution to reduce the pH of the reaction vessel solution to 10.5 or less The manufacturing method of the transition metal hydroxide precursor used for manufacture of the positive electrode active material for nonaqueous electrolyte secondary batteries containing a lithium transition metal complex oxide to be made. A transition metal hydroxide precursor produced by the production method according to claim 3 and a lithium compound are mixed and fired at 750 to 940 ° C.
Production of a positive electrode active material for a non-aqueous electrolyte secondary battery having an α-NaFeO ₂ type crystal structure and including a lithium transition metal composite oxide having a molar ratio of Li to transition metal (Me) (Li / Me) greater than 1 Method.   The non-aqueous electrolyte secondary battery according to claim 4, wherein when the transition metal hydroxide precursor and the lithium compound are mixed, a simple substance or compound of Ru, Te, Ce, Ta, or S is further mixed. A method for producing a positive electrode active material.   An electrode for a non-aqueous electrolyte secondary battery, comprising the positive electrode active material according to claim 1.   A nonaqueous electrolyte secondary battery comprising the electrode for a nonaqueous electrolyte secondary battery according to claim 6.

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