JP2018073752A - Positive electrode active material for nonaqueous electrolyte secondary battery, method for manufacturing 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 positive electrode active material which is large in discharge capacity per unit volume; an electrode for a nonaqueous electrolyte secondary battery, which is arranged by use of the positive electrode active material; and a nonaqueous electrolyte secondary battery.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 further includes Ru, Te or Fe element, and 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 half-value width (FWHM(104)) of a (104)-plane diffraction peak is 0.25° or more with Miller index hkl.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for producing the positive electrode active material, an electrode for a non-aqueous electrolyte secondary battery containing the positive electrode active material, and a non-aqueous 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, see Patent Documents 1, 2, and 5-7).

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, it is shown that a lithium transition metal composite oxide is 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 and [0120] Table 3).

  As a positive electrode active material for a non-aqueous electrolyte secondary battery, a lithium transition metal composite oxide containing Fe is known (see, for example, Patent Documents 2 and 3).

In Patent Document 2, “the following general formula:
_{xLi 2 M1O 3 - (1-} x) LiM2O 2 (1)
(Here, M1 is at least one metal element constituting a tetravalent cation, M2 is at least one metal element constituting a trivalent cation, and x is a real number satisfying 0 <x <1. is there);
Containing a solid solution represented by
Here, a part of M1 and / or M2 in the solid solution is substituted with at least one metal element M3 selected from the group consisting of Fe, Al, and Cr. Positive electrode active material. (Claim 1).
In addition, the paragraph [0025] states that “a part of M1 and / or M2 in the Li ₂ M1O ₃ -LiM2O ₂ solid solution is at least one selected from the group consisting of Fe, Al, and Cr. By substituting with the metal element M3, the distortion of the crystal structure that can be caused by the lithium ions in and out is reduced compared with the conventional Li ₂ M1O ₃ -LiM2O ₂ solid solution not substituted with M3, and at high output Therefore, the rate characteristics of the lithium secondary battery using this Li ₂ M1O ₃ -LiM2O ₂ solid solution as the positive electrode active material are preferably improved. "
In Examples, a raw material mixed slurry prepared by weighing lithium acetate, manganese acetate, cobalt acetate, nickel acetate and iron acetate, dissolving and mixing in water, and adding an appropriate amount of glycolic acid at 24 ° C. at 24 ° C. The precursor was prepared by evaporating water by heating for a period of time, and the precursor was calcined at 500 ° C. in the atmosphere, and this was pulverized once by a ball mill, and further calcined at 900 ° C. A positive electrode active material having a crystal structure belonging to the space group R-3m and having an overall composition of Li _1.2 [Mn _0.535 Fe _0.005 Co _0.13 Ni _0.13 ] O ₂ or the like is shown. (See paragraphs [0055] to [0058]).

  Also known is a positive electrode active material for a non-aqueous electrolyte secondary battery containing a lithium transition metal composite oxide that defines the half width of the diffraction peak of the (104) plane (2θ = 44 ± 1 °) by X-ray diffraction measurement. Yes (see, for example, Patent Documents 3 to 7).

Patent Document 3 states that “a positive electrode active material mainly composed of a Li—Mn—Ni based composite oxide, wherein the Li—Mn—Ni based composite oxide has a specific surface area of 0.3 m ² / g and 1.5 m ² / g or less. ”(Claim 1),“ The Li—Mn—Ni composite oxide is LiMn _0.5 Ni _0.5 O _2. A part of Mn and Ni constituting the composite oxide represented by the formula is substituted with a different element, and the following general formula:
Li _1-z [Mn _0.5-xy Ni _{0.5-x′-y ′} M _{x + x ′} Li _{y + y ′} O ₂ ]
(Where M is the different element;
x = 0.001 to 0.1; x ′ = 0.001 to 0.1;
y = 0-0.1; y ′ = 0-0.1;
x + x ′ + y + y ′ ≦ 0.4; 0 ≦ z ≦ 1)
2. The positive electrode active material according to claim 1, wherein the positive electrode active material is a composite oxide having a composition represented by: (Claim 3), "The different element M is at least one selected from the group consisting of B, Mg, Al, Ti, V, Cr, Fe, Co, Cu and Zn" 5. The positive electrode active material according to claim 3 or claim 4. (Claim 5) and “The Li—Mn—Ni composite oxide is 2θ of a powder X-ray diffraction diagram using CuKα rays. = 18.6 ± 1 ° The half width of the diffraction peak is 0.13 ° 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 The positive electrode active material according to any one of claims 1 to 12, which is .17 ° or less.
Further, in paragraph [0054], when any one of B, Mg, Al, Ti, V, Cr, Fe, Co, Cu, and Zn is used as the different element M, a particularly remarkable effect is obtained on the high rate discharge performance. Therefore, there is a description that it is more preferable.
In the examples, a coprecipitation compound containing manganese, nickel and iron was added to an aqueous lithium hydroxide solution, and after stirring, the solvent was evaporated and dried, followed by firing at 1000 ° C. for 12 hours in an oxygen atmosphere. The diffraction peak at 2θ = 44.1 ± 1 ° of the powder X-ray diffraction diagram of the positive electrode active material having a composition formula of LiMn _0.475 Ni _0.475 Fe _0.05 O _{2 and the} like produced using CuKα rays It is shown that the full width at half maximum is 0.11 ° to 0.14 ° (paragraph [0179], [0246] Table 2, paragraph [0198], [0247] Table 3, [0229], [ 0230], [0248] Table 4).

Patent Document 4 states that “the diffraction peak angles 2θ of the (003) plane and (104) plane at the Miller index hkl of powder X-ray diffraction using CuKα rays are 18.65 ° or more and 44.50 ° or more, respectively. The diffraction peak half-value widths of these surfaces are each 0.18 ° or less, and the diffraction peak angles 2θ of the (108) surface and (110) surface are 64.40 ° and 65.15 ° or more, respectively. diffraction peak of the plane - where click half width is less than both 0.18 °, made _{Li a Ni x Mn y Co z} O 2 + b (x + y + z = 1,1.00 <a <1.3,0 ≦ b <0.3) "A lithium-nickel-manganese-cobalt composite oxide having a layered structure having a chemical composition" (Claim 1).
Further, paragraph [0017] states that “the diffraction peak angles 2θ of the (003) plane and the (104) plane at the Miller index hkl of the powder X-ray diffraction using CuKα rays are more than 18.65 ° and 44.50 °, respectively. If it is small, the phase spacing decreases, the lithium ion diffusion is inhibited, and the charge / discharge characteristics deteriorate, and if the diffracted peak half-value widths of these planes are each greater than 0.18 °, crystal growth does not occur. The charge / discharge characteristics deteriorate due to lack of composition or large variation in composition. "
In Examples 1 to 3, the composition formula is Li _1.1 Ni _0.333 Mn _0.333 Co _0.333 O ₂ and the (104) plane diffraction peak half width is 0.141 ° to 0 Lithium / nickel / manganese / cobalt composite oxide at 165 ° is shown (paragraphs [0020] to [0021], [0022] Table 1, [0026] to [0028], [0030] to [0032]. ]reference).

In Patent Document 5, “a positive electrode active material containing a lithium transition metal composite oxide having an α-NaFeO ₂ structure,
In the lithium transition metal composite oxide, the transition metal (Me) includes Co, Ni and Mn,
The molar ratio (Li / Me) between Li and the transition metal (Me) is 1.15 ≦ Li / Me ≦ 1.24,
The molar ratio of Mn in the transition metal (Mn / Me) is 0.52 ≦ Mn / Me ≦ 0.66,
When the space group R3-m is used as the crystal structure model based on the X-ray diffraction pattern, the half-value width (FWHM (104)) of the diffraction peak attributed to the (104) plane is 0.285 ≦ FWHM (104) ≦ It is 0.335, The positive electrode active material for lithium secondary batteries characterized by the above-mentioned. (Claim 1).
The paragraph [0025] states that “The lithium transition metal composite oxide according to the present invention is attributed to the (104) plane when the space group R3-m is used as a crystal structure model based on the X-ray diffraction pattern. The half-value width FWHM (104) of the diffraction peak is in the range of 0.285 ° to 0.335 °, and the half-value width of the diffraction peak attributed to the (003) plane is 0.204 ° to 0.303 °. By doing so, it is possible to increase the discharge capacity of the positive electrode active material, improve the high rate discharge performance, and stabilize the OCV, where 2θ = 18. The diffraction peak of .6 ° ± 1 ° is in the (003) plane at the Miller index hkl in the space group P3 ₁ 12 and R3-m, and the diffraction peak of 2θ = 44.1 ° ± 1 ° is in the space group P3 ₁ 12 (114) plane In the space group R3-m, the (104) plane is indexed. ”
And in paragraphs [0069] to [0076] and [0090] Table 1, the transition metal coprecipitated carbonate precursor and lithium carbonate were mixed so as to have various compositions and fired at 720 to 920 ° C. When X-ray diffraction measurement was performed on the active material, it was described that the half width of the diffraction peak indexed on the (104) plane in the space group R-3m was 0.257 ° to 0.346 °. .

Patent Document 6 states that “the composition formula is Li _{1 + α} Me _1-α O ₂ (Me is a transition metal element including Co, Ni, and Mn, 1.2 ≦ (1 + α) / (1-α) ≦ 1.4). A lithium secondary battery positive electrode active material containing a lithium transition metal composite oxide, wherein the lithium transition metal composite oxide has a Co molar ratio of Co / Me in the Me of 0.20 to 0. .36, and 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 attributed to the (104) plane is in the range of 0.262 ° to 0.424 °. The positive electrode active material for a lithium secondary battery, ”(Claim 1).
In addition, in paragraph [0020], “When the lithium transition metal composite oxide according to the present invention uses the space group R3-m as a crystal structure model based on an X-ray diffraction (using a CuKα radiation source) pattern ( 104) The half width of the diffraction peak attributed to the plane is in the range of 0.262 ° to 0.424 °, whereby the discharge capacity of the positive electrode active material can be increased and the energy density can be improved. In addition, by setting the half-value width of the diffraction peak in the range of 0.278 ° to 0.424 °, it is possible to improve the high rate discharge performance as well as the energy density, where 2θ = 44 ± 1. diffraction peak ° is described as the space group _P3 1 12 (114) plane. are respectively indexed to the space group in R3-m (104) plane ".
Paragraphs [0066] to [0079], [0082], [0090] Table 1, [0094] to [00099], and [0110] Table 2 include transition metal coprecipitated carbonate precursors and lithium carbonate. When the X-ray diffraction measurement was performed on the active material which was mixed to have various compositions and fired at 750 to 850 ° C., the half width of the diffraction peak indexed on the (104) plane in the space group R-3m was It is described that it was 0.253 degree-0.445 degree.

Patent Document 7 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 [0090], [0102] Table 1, and [0103] Table 2, various transition metal coprecipitated hydroxide precursors, lithium hydroxide monohydrate, and sodium carbonate When the crystal structure analysis was performed on the active material mixed at a composition and fired at 700 to 1050 ° C., the half-value width of the diffraction peak on the (003) plane was 0.17 to 0.32 °, and the (114) plane was It was described that the half width of the diffraction peak was 0.35 to 0.54 °.

WO2012 / 091015 JP 2012-129102 A JP 2009-59710 A JP 2005-53764 A JP 2006-143447 A JP 2014-44945 A WO2012 / 039413

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.
In addition, when a coprecipitated carbonate precursor of a transition metal element is used as a precursor for producing an active material, an active material having porous and fine primary particles can be obtained. Thus, the high rate discharge performance can be improved. However, although the active material using the carbonate precursor has an excellent capacity per weight, the active material becomes porous, so that the capacity per volume is not sufficient. On the other hand, when a co-precipitated hydroxide precursor of a transition metal element is used as the precursor, the particle size tends to be large, and it is difficult to increase the density of the precursor by an ordinary production method. Therefore, when this production method is applied to an “lithium-excess type” active material, the diffusion efficiency of Li ions is lowered and it is difficult to improve the capacity per volume.

  As shown in FIG. 1, the present inventor was prepared from a carbonate precursor by using a hydroxide precursor obtained by a specific manufacturing method as a precursor of a “lithium-rich” positive electrode active material. Although a positive electrode active material having a smaller total pore volume and a larger discharge capacity per volume than the positive electrode active material was obtained, further improvement in discharge capacity is desired.

Patent Document 2 describes a lithium transition metal composite oxide containing Fe as a positive electrode active material for a lithium secondary battery, but there is no description about the half width of the peak by X-ray diffraction measurement, There is no description about improving the capacity of the battery.
Patent Documents 3 and 4 disclose a positive electrode active material containing a “lithium-rich” 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 0.25 ° or more. There is no description about improving the capacity per volume. Patent Documents 3 and 4 do not specifically show “lithium-excess type” lithium transition metal composite oxides.

  Patent Documents 5 to 7 each describe a positive electrode active material for a lithium secondary battery containing a lithium transition metal composite oxide having a half-width of a diffraction peak of (104) plane measured by X-ray diffraction measurement of 0.25 ° or more. However, there is no description that the lithium transition metal composite oxide contains Ru, Te or Fe elements, and there is no description about improving the discharge capacity per volume.

  An object of the present invention is to provide a positive electrode active material having a large discharge capacity per volume, a nonaqueous electrolyte secondary battery electrode using the positive electrode active material, and 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, and the lithium transition metal composite oxide further includes an element of Ru, Te, or Fe, and has an X-ray diffraction pattern that can be assigned to the space group R3-m, Positive electrode for non-aqueous electrolyte secondary battery in which the half-value width (FWHM (104)) of the diffraction peak of (104) plane at Miller index hkl is 0.25 ° or more by X-ray diffraction measurement using Cu-Kα ray Active material " Use.

Another aspect of the present invention is “a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery including a lithium transition metal composite oxide, which includes Ni and Mn, or Ni, Co and Mn in a solution. The transition metal compound is coprecipitated to produce a transition metal hydroxide precursor, and the transition metal hydroxide precursor, the lithium compound, and a simple substance or compound of Ru, Te, or Fe are mixed, and 750 ° C. or higher and 850 ° C. Firing at the following temperature, having an α-NaFeO ₂ structure, containing 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, and further produces a lithium transition metal composite oxide containing Ru, Te or Fe element. For batteries Method of manufacturing the active material. "Is.

Another aspect of the present invention is “a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery including a lithium transition metal composite oxide, which includes Ni and Mn, or Ni, Co and Mn in a solution. A transition metal hydroxide precursor is produced by co-precipitation of a transition metal compound containing Fe together with a transition metal compound,
The transition metal hydroxide precursor and the lithium compound are mixed and fired at a temperature of 750 ° C. or higher and 850 ° C. or lower to have an α-NaFeO ₂ structure, and Mn and Ni or Mn as a transition metal element (Me) Mn / Me molar ratio Mn / Me 0.5 <Mn / Me, Li / Me molar ratio Li / Me 1 <Li / Me, and Fe element The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries which manufactures the lithium transition metal complex oxide containing. Is.

  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, a positive electrode active material having a large discharge capacity (energy density) per volume, a nonaqueous electrolyte secondary battery electrode containing the positive electrode active material, and a nonaqueous electrolyte secondary battery including the electrode are provided. Can be provided.

The figure which shows the total pore volume of the positive electrode active material produced from the hydroxide precursor, and the positive electrode active material produced from the carbonate precursor. 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, the discharge capacity per volume of the positive electrode active material is improved.
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, the tap density of the hydroxide precursor can be improved and the discharge capacity per volume is improved.
Co contained in the lithium transition metal composite oxide has an effect of improving the initial efficiency. However, when too much Co is present, the tap density of the precursor is lowered, and the discharge capacity per volume of the positive electrode active material is reduced. . 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 nonaqueous electrolyte secondary battery having a large discharge capacity per volume can be obtained.

The lithium transition metal composite oxide according to this embodiment further contains a Ru, Te, or Fe element in addition to the lithium and the transition metal element.
When the lithium transition metal composite oxide contains these elements, the discharge capacity per volume is improved.
The content of the Ru, Te or Fe element is not particularly limited, but considering the effect of improving the discharge capacity per volume due to the increase in content and the increase in raw material cost, the total content of Ni, Co and Mn It is preferable to set it as 1-10 mol%, 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 has a half-width FWHM (104) of the diffraction peak attributed to the (104) plane. ) Is 0.25 ° or more. The value is preferably 0.30 ° or more, and more preferably 0.36 ° or more.
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 0.25 ° or more, crystallization does not proceed excessively and the crystallite is not enlarged, so that Li ions are sufficiently diffused, and the discharge capacity per volume is improved. .
The upper limit of FWHM (104) is not particularly limited, but is preferably 1.00 ° or less, and more preferably 0.96 ° or less, from the viewpoint of Li ion transport efficiency.
The diffraction peak of 2θ = 44.1 ° ± 1 ° is 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).

In the lithium transition metal composite oxide according to the present embodiment, the ratio of the half width of the diffraction peak attributed to the (003) plane to the FWHM (104), that is, the value of FWHM (003) / FWHM (104) is 0. 0.72 or less is preferable, and 0.60 or less is more preferable.
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 can be smoothly inserted and removed from the interlayer, and the discharge capacity per volume can be increased.
The lower limit of FWHM (003) / FWHM (104) is not particularly limited, but is preferably 0.25 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 electrolytic solution.
The diffraction peak at 2θ = 18.6 ° ± 1 ° is indexed to the (003) plane in the Miller index hkl in the space groups P3 ₁ 12 and R3-m.

(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.

The lithium transition metal composite oxide particles according to this embodiment preferably have a tap density of 1.8 g / cm ³ or more, and more preferably 1.9 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.

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.

If the sample used for the above various measurements 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.

  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 the present embodiment is a method in which a transition metal hydroxide precursor, a lithium compound (Li compound), and a simple substance or compound of Ru, Te or Fe are mixed and then fired, or a transition containing Fe It can manufacture suitably by the method of baking, after mixing a metal hydroxide precursor and Li compound.

As the transition metal hydroxide precursor used for the production of the lithium transition metal composite oxide, the transition metal (Me) contains Mn and Ni, or Mn, Ni and Co, and the transition metal (Me) contains Mn. It is preferable that the molar ratio Mn / Me is larger than 0.5, the crystal form is a high-density granule, and the tap density is preferably 1.3 g / cm ³ or more, more preferably 1.4 g / cm ³ or more. preferable.
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.
When the lithium transition metal composite oxide containing an Fe element is produced, a hydroxide precursor further containing Fe as a transition metal can be obtained.

Since the lithium transition metal composite oxide produced using the transition metal hydroxide precursor according to this embodiment is a “lithium-excess” active material, Mn of the transition metal element Me in the hydroxide precursor The molar ratio Mn / Me is greater than 0.5. Within this range, the reversible capacity of the active material can be increased.
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 preparing the hydroxide precursor, Mn of the transition metal is easily oxidized, and it is not easy to prepare a coprecipitation precursor in which the transition metal is uniformly distributed in a divalent state. Uniform mixing at the level tends to be inadequate. In particular, in the composition range of the present embodiment, since the Mn ratio is higher than the Ni, Co, and Fe 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 (CO ₂ ), or the like can be used.

  The pH (reaction tank pH) in the step of producing a hydroxide precursor by co-precipitation of a compound containing a transition metal in the solution is not limited, but can be 8-14. In order to increase the tap density, it is preferable to control the pH. By setting the pH to 11.5 or less, the tap density can be increased and the high rate discharge performance can be improved. Furthermore, since the particle growth rate can be accelerated by setting the pH to 11.0 or less, the stirring continuation time after completion of dropping of the raw material aqueous solution can be reduced.

  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 nickel compound include cobalt sulfate, cobalt nitrate, and cobalt acetate. Examples of the Fe compound include iron sulfate, iron nitrate, and iron 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 8 to 11.5, the stirring duration is 0.5 to 3 h. preferable.

  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.

The simple substance or compound of Ru, Te or Fe mixed with the hydroxide precursor and the Li compound includes Ru, RuO ₂ , RuF ₆ , RuCl ₃ , Te, TeO ₂ , TeO ₃ , TeCl ₄ , Li ₂ TeO _3. Fe, Fe ₂ O ₃ , Fe ₃ O ₄ , Fe (OH) ₃ , FeOOH, FePO ₄ , FeCl ₂ , FeCl ₃ , FeS, Fe (NO ₃ ) ₂ , Fe (NO ₃ ) ₃ , FeSO ₄ , Fe ₂ (SO ₄ ) ₃ or the like can be used.

The temperature at which the transition metal hydroxide precursor, the Li compound, and the simple substance or mixture of Ru, Te, or Fe or a mixture of the compounds affects the size of the FWHM (104) and the discharge capacity per volume of the active material.
If the firing temperature is too high, the crystallization of the lithium transition metal composite oxide in the active material proceeds too much, the crystallite becomes large, and Li ions are not sufficiently diffused, resulting in a decrease in discharge capacity per volume. . At this time, the FWHM (104) of the lithium transition metal composite oxide becomes small. In the present embodiment, the firing temperature is preferably 850 ° C. or less, and more preferably 800 ° C. or less.
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 750 ° C. or higher. By sufficiently crystallizing, the resistance of the crystal grain boundary can be reduced and smooth lithium ion transport can be promoted.

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. Moreover, FWHM (104) is 0.25 ° or more.

[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. 2 is 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. 2, the 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. 3, 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 tank, and N ₂ gas was bubbled for 30 minutes to remove oxygen contained in the ion exchange water. The temperature of the reaction vessel 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 vessel. 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>
Lithium hydroxide monohydrate 1.288 g and ruthenium dioxide 0.037 g are added to 2.230 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: 1 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, 1.278 g of lithium hydroxide monohydrate and 0.112 g of ruthenium dioxide are added to 2.168 g of the hydroxide precursor, and the molar ratio of (Ni, Co, Mn): Ru is 100: A lithium transition metal composite oxide according to Example 2 was produced in the same manner as in Example 1 except that the mixed powder of 3 was prepared.

(Example 3)
In the firing step, 1.267 g of lithium hydroxide monohydrate and 0.186 g of ruthenium dioxide are added to 2.110 g of the hydroxide precursor, and the molar ratio of (Ni, Co, Mn): Ru is 100: A lithium transition metal composite oxide according to Example 3 was produced in the same manner as in Example 1 except that the mixed powder of 5 was prepared.

Example 4
In the firing step, 1.294 g of lithium hydroxide monohydrate and 0.053 g of lithium tellurite are added to 2.262 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn) is The lithium transition metal composite oxidation according to Example 4 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: 1 was prepared. A product was made.

(Example 5)
In the firing step, 1.294 g of lithium hydroxide monohydrate and 0.263 g of lithium tellurite are added to 2.262 g of the hydroxide precursor, and the molar ratio of (Ni, Co, Mn): Te is A lithium transition metal composite oxide according to Example 5 was produced in the same manner as in Example 4 except that a mixed powder of 100: 5 was prepared.

(Example 6)
<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, 530.4 g of manganese sulfate pentahydrate, 48.5 g of iron nitrate nonahydrate, and 138.7 g of ammonium fluoride. These are weighed and dissolved in 4 L of ion-exchanged water. The molar ratio of Ni: Co: Mn is 30:15:55, the molar ratio of (Ni, Co, Mn): Fe is 100: 3, and ammonium fluoride. A 1.0 M aqueous sulfate solution having a concentration of 0.938 M was prepared. Next, ₂ L of ion exchange water was poured into a 5 L reaction tank, and N ₂ gas was bubbled for 30 minutes to remove oxygen contained in the ion exchange water. The temperature of the reaction vessel 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 vessel. 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 alkaline solution composed of 4.0 M sodium hydroxide, 0.313 M ammonia, and 0.1 M hydrazine is appropriately dropped to adjust the pH in the reaction vessel. Control was performed so as to always maintain 10.05 (± 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>
1.294 g of lithium hydroxide monohydrate is added to 2.262 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn, Fe) is 120: 100, (Ni, Co, Mn) A lithium transition metal composite oxide according to Example 6 was produced in the same manner as in Example 1 except that a mixed powder having a molar ratio of: Fe of 100: 3 was prepared.

(Example 7)
In the firing step, 1.214 g of lithium hydroxide monohydrate is added to 2.315 g of the hydroxide precursor, and a mixed powder having a molar ratio of Li: (Ni, Co, Mn, Fe) of 110: 100 A lithium transition metal composite oxide according to Example 7 was produced in the same manner as in Example 6 except that the body was prepared.

(Comparative Example 1)
In the firing step, except that 1.294 g of lithium hydroxide monohydrate was added to 2.262 g of the hydroxide precursor, and a mixed powder substantially free of Ru, Te and Fe was prepared. In the same manner as in Example 1, a lithium transition metal composite oxide according to Comparative Example 1 was produced.

(Comparative Example 2)
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 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): K of 100: 3 was prepared. A product was made.

(Comparative Example 3)
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 4)
In the firing step, 1.292 g of lithium hydroxide monohydrate and 0.207 g of copper sulfate pentahydrate are added to 2.192 g of the hydroxide precursor, and Li: (Ni, Co, Mn, Cu). The lithium according to Comparative Example 4 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): Cu of 100: 3 was prepared. A transition metal composite oxide was produced.

(Comparative Example 5)
In the firing step, 1.288 g of lithium hydroxide monohydrate and 0.086 g of germanium dioxide are added to 2.186 g of the hydroxide precursor, and the molar ratio of Li: (Ni, Co, Mn, Ge) is Lithium transition metal composite oxidation according to Comparative Example 5 in the same manner as in Example 1 except that a mixed powder having a molar ratio of 120: 100 and (Ni, Co, Mn): Ge of 100: 3 was prepared. A product was made.

(Comparative Example 6)
In the baking 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, 1.312 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. The lithium transition metal composite oxidation according to Comparative Example 7 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): Be of 100: 3 was prepared. A product was made.

(Comparative Example 8)
In the firing step, 1.294 g of lithium hydroxide monohydrate and 0.123 g of lithium niobate are added to 2.262 g of the hydroxide precursor, and a molar ratio of Li: (Ni, Co, Mn, Nb) 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): Nb of 100: 3 was prepared. An oxide was produced.

(Example 8)
A lithium transition metal composite oxide according to Example 8 was produced in the same manner as in Example 6 except that the firing temperature was 850 ° C. in the firing step.

(Comparative Example 9)
A lithium transition metal composite oxide according to Comparative Example 9 was produced in the same manner as in Example 6 except that the firing temperature was 900 ° C. in the firing step.

(Examples 9 and 10)
In the firing step, the lithium transition metal composite oxide according to Example 9 was treated in the same manner as in Example 1 except that the firing temperature was 750 ° C. The lithium transition metal composite according to Example 10 was treated in the same manner as in Example 4. Each oxide was prepared.

(Example 11)
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). Except for this, a lithium transition metal composite oxide according to Example 11 was produced in the same manner as in Example 1.

(Example 12)
In the firing step, 1.294 g of lithium hydroxide monohydrate and 0.052 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. Lithium transition metal composite oxidation according to Example 12 except that a mixed powder having a molar ratio of 120: 100 and (Ni, Co, Mn): Te of 100: 1 was prepared. A product was made.

(Example 13)
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, 2.185 g of the hydroxide precursor was added with water. 1.367 g of lithium oxide monohydrate and 0.038 g of ruthenium dioxide were added, and the molar ratio of Li: (Ni, Co, Mn, Ru) was 130: 100, and the mole of (Ni, Co, Mn): Ru. A lithium transition metal composite oxide according to Example 13 was produced in the same manner as in Example 1 except that a mixed powder having a ratio of 100: 1 was prepared.

(Example 14)
In the firing step, 1.373 g of lithium hydroxide monohydrate and 0.054 g of lithium tellurite are added to 2.211 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 14 is the same as Example 13 except that a mixed powder having a molar ratio of 130: 100 and (Ni, Co, Mn): Te of 100: 1 is prepared. A product was made.

(Example 15)
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, 1.25M ammonia, and 0.5M hydrazine, the pH in the reaction vessel was controlled so as to always maintain 9.8 (± 0.1). In the firing step, 1.209 g of lithium hydroxide monohydrate and 0.036 g of ruthenium dioxide are added to 2.283 g of the hydroxide precursor, and Li: (Ni, Co, Mn, Ru) Mole 110: 100 and (Ni, Co, Mn): Ru mixed powder having a molar ratio of 100: 1 was prepared in the same manner as in Example 1 except that the lithium transition metal composite according to Example 15 was prepared. An oxide was produced.

(Example 16)
In the firing step, 1.214 g of lithium hydroxide monohydrate and 0.051 g of lithium tellurite are added to 2.315 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 16 was performed in the same manner as Example 15 except that a mixed powder having a molar ratio of 110: 100 and (Ni, Co, Mn): Te was 100: 1 was prepared. A product was made.

(Example 17)
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 0.1M hydrazine. 1.365 g of lithium hydroxide monohydrate and 0.038 g of ruthenium dioxide are added to 2.181 g of the precursor, and the molar ratio of Li: (Ni, Co, Mn, Ru) is 130: 100, (Ni, C , Mn): molar ratio of Ru 100: except that the preparation of the mixed powder is 1, in the same manner as in Example 1 to prepare a lithium transition metal composite oxide according to Example 17.

(Example 18)
In the firing step, 1.371 g of lithium hydroxide monohydrate and 0.054 g of lithium tellurite are added to 2.211 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 18 was performed in the same manner as in Example 17 except that a mixed powder having a molar ratio of 130: 100 and (Ni, Co, Mn): Te of 100: 1 was prepared. A product was made.

(Measurement of tap density of lithium transition metal composite oxide)
The tap densities of the lithium transition metal composite oxides according to Examples 1 to 18 and Comparative Examples 1 to 9 were measured by REI ELECTRIC CO. LTD. Using a tapping device (manufactured in 1968) manufactured by the company, the measurement was performed according to the conditions and procedures described above.

(Confirmation of α-NaFeO type ₂ crystal structure)
It was confirmed that the lithium transition metal composite oxides according to Examples 1 to 18 and Comparative Examples 1 to 9 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 18 and Comparative Examples 1 to 9 are measured using an X-ray diffractometer (manufactured by Rigaku, model name: MiniFlex II) according to the conditions and procedures described above. 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.

(Measurement of pore volume)
For the lithium transition metal composite oxides according to Examples 1, 4 and 6, the total pore volume and the peak differential pore volume were measured according to the conditions and procedures described above. The results are shown in Table 1.

[Preparation of electrode for non-aqueous electrolyte secondary battery]
Using the lithium transition metal composite oxides according to Examples 1 to 18 and Comparative Examples 1 to 9 as positive electrode active materials, respectively, the non-aqueous electrolyte secondary according to Examples 1 to 18 and Comparative Examples 1 to 9 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, a solution in which LiPF6 is dissolved in a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC) in a volume ratio of 6: 7: 7 so that the concentration becomes 1 mol / l. 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.

  Next, a one-cycle charge / discharge test was performed. Charging was performed at a constant current and constant voltage with a current of 0.1 CmA and a voltage of 4.45 V, and the charge termination condition was when the current value was 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. Here, a pause process of 10 minutes was provided after charging and discharging, respectively. The discharge capacity (mAh / g) of the positive electrode active material in this cycle was recorded.

(Measurement of limit mixture density)
A plurality of non-aqueous electrolyte secondary battery electrodes according to Examples 1 to 18 and Comparative Examples 1 to 9 prepared above were cut into a size of 2 cm × 2 cm, respectively, and a flat plate press (manufactured by RIKEN SEIKI Co. LTD. CDM-20M TYPE P-1B), various post-pressing electrodes having different electrode plate thicknesses were produced by applying various pressing pressures from 1 MPa to 15 MPa. The mixture density (g / cm ³ ) was calculated from the thickness and weight of each post-press electrode.
Each pressed electrode was dried under reduced pressure for 12 h under a temperature environment of 120 ° C., and after sufficiently removing the contained water, a line connecting each midpoint of two opposing sides of a 2 cm × 2 cm square was folded. As described above, nothing was sandwiched between the valleys, and it was folded by hand to make the other two opposite sides coincide. Furthermore, the crest portion of the fold that was curved and formed into a U-shape was pressed to bring the surfaces of the electrodes into contact with each other over the entire surface. Next, the sheet is spread again to the original flat shape, the electrode is directed toward the visible light source, the bent portion is visually observed, and the portion of the mixture layer is determined depending on whether visible light is observed through the bent portion. The presence or absence of damage was confirmed. And the electrode which has the smallest thickness among the electrodes by which damage was not recognized was determined, and the said mixture density (g / cm < ³ >) which concerns on the said electrode is the nonaqueous electrolyte secondary which concerns on the said Example or a comparative example It was defined as “limit mixture density (g / cm ³ )” of the battery electrode.

For each of the examples and comparative examples, the discharge capacity per unit volume “0.1 C” is obtained by multiplying the value of the discharge capacity (mAh / g) by the value of the limit mixture density (g / cm ³ ). The capacity (mAh / cm ³ ) ”was calculated.

  Ni / Co / Mn molar ratio, Li / Me ratio, firing temperature, tap density, additive element type and addition amount of lithium transition metal composite oxides according to Examples 1 to 18 and Comparative Examples 1 to 9, FWHM ( 104), FWHM (003) / FWHM (104), 0.1 C capacity of a non-aqueous electrolyte secondary battery using the lithium transition metal composite oxide as a positive electrode active material, respectively, and the lithium transition metal composite oxide. The limit mixture density of the electrode used as a substance is shown in Tables 2-4.

From Table 2-4, have alpha-NaFeO ₂ structure, as the transition metal (Me), Ni and Mn, or Ni, comprising Co and Mn, with Li / Me> 1, with Mn / Me> 0.5 In addition, the nonaqueous electrolyte secondary battery using the lithium transition metal composite oxide according to Examples 1 to 18 containing Ru, Te or Fe element and having FWHM (104) of 0.25 ° or more is It can be seen that the discharge capacity of 0.1 C is large.
Such a lithium transition metal composite oxide includes, as a transition metal element (Me), a coprecipitation precursor of transition metal hydroxide containing Ni and Mn or Ni, Co and Mn, a lithium compound, and Ru, Te. Alternatively, a simple substance or a compound of Fe is mixed and fired at a temperature of 750 ° C. or higher and 850 ° C. or lower, or transition metal hydroxide containing Fe as a transition metal element (Me) or Ni, Co, and Mn. It is obtained when a lithium compound is mixed with the coprecipitation precursor of the product and fired at a temperature of 750 ° C. or higher and 850 ° C. or lower.

On the other hand, as in Comparative Examples 1 to 8, the lithium transition metal composite oxide containing no Ru, Te or Fe element is a non-aqueous electrolyte using this even if FWHM (104) is 0.25 ° or more The 0.1 C capacity per volume of the secondary battery is small.
Further, as in Comparative Example 9, the lithium transition metal composite oxide having a high firing temperature during production and FWHM (104) of 0.25 ° or less may contain Ru, Te or Fe elements. The non-aqueous electrolyte secondary battery using the battery has a small 0.1 C capacity per volume.

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 And a lithium transition metal composite oxide that further includes a Ru, Te, or Fe element and satisfies a requirement that FWHM (104) is 0.30 ° or more, as a positive electrode active material of a non-aqueous electrolyte secondary battery. A non-aqueous electrolyte secondary battery having a large discharge capacity per volume can be provided.
Such a lithium transition metal composite oxide includes, as a transition metal element (Me), a coprecipitation precursor of transition metal hydroxide containing Ni and Mn or Ni, Co and Mn, a lithium compound, and Ru. , Te or Fe simple substance or compound is mixed and fired at a temperature of 750 ° C. or higher and 850 ° C. or lower, or transition metal element (Me) includes Ni and Mn, or transition metal containing Fe together with Ni, Co and Mn It is obtained when a lithium compound is mixed with a hydroxide coprecipitation precursor and calcined at a temperature of 750 ° C. or higher and 850 ° C. or lower.

  By using the positive electrode active material including the lithium transition metal composite oxide according to one aspect of the present invention, a nonaqueous electrolyte secondary battery having a large discharge capacity per volume can be provided. The battery is useful as a nonaqueous 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 (5)

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,
The lithium transition metal composite oxide further includes a Ru, Te, or Fe element,
Having an X-ray diffraction pattern that can be assigned to the space group R3-m;
Positive electrode for non-aqueous electrolyte secondary battery in which the half-value width (FWHM (104)) of the diffraction peak of (104) plane at Miller index hkl is 0.25 ° or more by X-ray diffraction measurement using Cu-Kα ray Active material. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery comprising a lithium transition metal composite oxide,
Producing a transition metal hydroxide precursor by coprecipitation of a transition metal compound containing Ni and Mn or Ni, Co and Mn in a solution;
Mixing the transition metal hydroxide precursor, the lithium compound, and a simple substance or compound of Ru, Te or Fe;
Firing at a temperature of 750 ° C. or higher and 850 ° C. or lower,
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,
Furthermore, the manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries which manufactures the lithium transition metal complex oxide containing Ru, Te, or Fe element. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery comprising a lithium transition metal composite oxide,
Producing a transition metal hydroxide precursor by co-precipitation of a transition metal compound containing Fe with Ni and Mn or a transition metal compound containing Ni, Co and Mn in a solution;
Mixing the transition metal hydroxide precursor and the lithium compound;
Firing at a temperature of 750 ° C. or higher and 850 ° C. or lower,
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,
Furthermore, the manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries which manufactures the lithium transition metal complex oxide containing Fe element.   An electrode for a non-aqueous electrolyte secondary battery, comprising the positive electrode active material according to claim 1.   A non-aqueous electrolyte secondary battery comprising the electrode for a non-aqueous electrolyte secondary battery according to claim 4.

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