JP6527200B2 - Positive electrode active material for lithium ion secondary battery or positive electrode active material for sodium ion secondary battery, and manufacturing method thereof - Google Patents

Description

  The present invention is a positive electrode active for a lithium ion secondary battery having a layered rock salt structure, which has excellent workability in the production process of the positive electrode and can have both excellent discharge characteristics and safety in the case of a secondary battery. The present invention relates to a substance or a positive electrode active material for a sodium ion secondary battery, and a method for producing them.

  Layered lithium composite oxides such as layered lithium-nickel-cobalt-manganese composite oxide (NCM) and layered-type lithium-nickel-cobalt-aluminum composite oxide (NCA) comprise a lithium atomic layer and a transition metal atomic layer Has a layered crystal structure alternately stacked via an atomic oxygen layer, and has a so-called layered rock salt structure in which one lithium atom is contained per one transition metal atom. Such layered lithium composite oxide is used as a positive electrode active material that can constitute a high output and high capacity lithium ion secondary battery.

  In a lithium ion secondary battery using such a layered lithium composite oxide as a positive electrode active material, charging and discharging are carried out by the lithium ions being desorbed and inserted into the layered lithium composite oxide. As the discharge cycles are repeated, capacity reduction occurs, and particularly when used for a long time, the capacity reduction of the battery may be significant. It is believed that this is because the dissolution of the transition metal component of the layered lithium composite oxide into the electrolytic solution during charging easily causes the collapse of the crystal structure. In addition, the elution of the transition metal component into the electrolytic solution may lower the thermal stability of the lithium ion secondary battery and impair the safety.

Therefore, when using a layered lithium composite oxide as a positive electrode active material, another lithium positive electrode active material excellent in safety is mixed with the layered lithium composite oxide to dilute the layered lithium composite oxide, Technologies to ensure safety have been developed. For example, Patent Document 1 contains a layered lithium-nickel-manganese-cobalt composite oxide in an amount of 65% by mass or more of the total mass of the positive electrode mixture, and further Li _{1 + x} MPO ₄ (0 ≦ x ≦ 1, M is Li, Fe A positive electrode including 10% by mass or more of a lithium composite oxide having an olivine type structure represented by one or more elements selected from Ni, Co, Mn, Ti, Cu, Zn, Mg, and Zr) Discloses a technology for enhancing the safety of a lithium ion secondary battery.

  On the other hand, since lithium is a rare and valuable substance, it has a layered rock salt structure similar to the layered lithium composite oxide, and can be charged and discharged with sodium ions instead of lithium ions, useful as a positive electrode active material So-called layered sodium complex oxides have also been developed. For example, Patent Document 2 discloses a positive electrode active material composed of a composite metal oxide containing sodium and two or more metal elements selected from the group consisting of Fe, Mn, Ni, Co and Ti.

JP, 2016-76317, A Unexamined-Japanese-Patent No. 2010-80424

  By the way, in order to manufacture a positive electrode of a lithium ion secondary battery or a sodium ion secondary battery using a positive electrode active material composed of such a layered composite oxide etc., such a positive electrode active material, a conductive aid such as carbon black, and A solvent such as N-methyl-2-pyrrolidone is added to a binder such as polyvinylidene fluoride and sufficiently kneaded to prepare a positive electrode slurry, which is uniformly dispersed on a current collector such as an aluminum foil. After application to a desired thickness, it is consolidated and dried by a roller press or the like.

  As the positive electrode slurry prepared as described above, it is required that the flow characteristics such as viscosity are unlikely to change with time, but the lithium composite oxide described in Patent Document 1 is used to prepare a positive electrode slurry. Then, the viscosity increases with the passage of time after the kneading, and the coating thickness may be uneven on the current collector to such an extent that the viscosity can not be eliminated even if it is finally consolidated. Therefore, there is a concern that the thickness of the positive electrode material on the current collector becomes a non-uniform positive electrode and the discharge capacity of the obtained lithium ion secondary battery is reduced.

  Therefore, the object of the present invention is to obtain a lithium ion which can be prepared a slurry having stable workability (hereinafter referred to as “positive electrode slurry”) without viscosity change with time in the manufacturing process of the positive electrode. In a secondary battery or a sodium ion secondary battery, a positive electrode active material for a lithium ion secondary battery or a positive electrode for a sodium ion secondary battery comprising a layered composite oxide capable of securing both excellent discharge capacity and safety It is to provide an active material.

  Therefore, as a result of intensive studies, the present inventors have found that a specific polyanion particle and a composite oxide particle are composited only on a part of the surface of a layered composite oxide secondary particle consisting of a specific composite oxide particle. By making the positive electrode active material having a specific peak intensity by XPS, and making it possible to prepare a positive electrode slurry that is less likely to change in viscosity with time, lithium ion 2 having excellent discharge characteristics and safety It has been found that a secondary battery or a sodium ion secondary battery can be obtained.

That is, the present invention relates to the following formula (I):
LiNi _a Co _b Mn _c M ¹ _x O ₂ (I)
(In the formula (I), M ¹ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, And one or more elements selected from Bi and Ge, a, b, c, x, 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number satisfying 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + (valence of M ¹ ) × x = 3)
Or, the following formula (II):
LiNi _d Co _e Al _f M ² _y O ₂ (II)
(Wherein M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and D represents one or more elements selected from Ge, d, e, f and y each satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ It shows a number satisfying y ≦ 0.3 and 3d + 3e + 3f + (valence of M ² ) × y = 3)
In part of the surface of the layered lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (V):
LiCo _g M ⁵ _i PO ₄ (V)
(In the formula (V), M ⁵ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G and i satisfy 0 <g ≦ 1 , 0 ≦ i ≦ 0.3, and 2 g + (number of valences of M ⁵ ) × i = 2.
Or, the following formula (VI):
LiFe _m Mn _n M ⁶ _o PO ₄ (VI)
(In the formula (VI), M ⁶ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ⁶ ) × o = 2 is satisfied.)
And lithium complex polyanion particles (B) formed by supporting carbon (c) on the surface, and lithium complex oxide particles are complexed,
The secondary lithium ion whose peak intensity ratio ((peak intensity of Ni2p _3/2 ) / (peak intensity of P2p + peak intensity of C1s)) by X-ray photoelectron spectroscopy (XPS) is more than 0.05 and less than 0.4 The present invention provides a battery positive electrode active material.

Moreover, the present invention provides the following formula (III):
NaNi _{a '} Co _b' Mn _{c '} M ³ _x' O ₂ (III)
(Wherein M ³ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, A ', b', c 'and x' each represents 0.3 ≦ a ′ <1, 0 <b ′ ≦ 0.7, 0 <a c ′ ≦ 0.7, 0 ≦ x ′ ≦ 0.3, and 3a ′ + 3b ′ + 3c ′ + (valence number of M ³ ) × x ′ = 3.
Or, the following formula (IV):
NaNi _d' Co _{e '} Al _f' M ⁴ _{y '} O ₂ (IV)
(Wherein, in the formula (IV), M ⁴ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and And d ′, e ′, f ′ and y ′ each represent 0.4 ≦ d ′ <1, 0 <e ′ ≦ 0.6, 0 <f ′.数 0.3, 0 y y '0.3 0.3, and 3d' + 3e '+ 3f' + (valence number of M ⁴ ) x y '= 3 is satisfied.)
In part of the surface of the layered sodium complex oxide secondary particles (D) consisting of sodium complex oxide particles represented by the following formula (VII):
NaCo _{g '} M ⁷ _i' PO ₄ ... (VII)
(In the formula (VII), M ⁷ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G ′ and i ′ satisfy 0 <g '0 1, 0 i i' 2 0.3, and 2g '+ (valence number of M ⁷ ) = 2i' = 2 is satisfied),
Or the following formula (VIII):
NaFe _{m '} Mn _n' M ⁸ _{o '} PO ₄ ... (VIII)
(In the formula (VIII), M ⁸ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M ′, n ′, and o ′ are 0 ≦ m ′ ≦ 1, 0 ≦ n ′ ≦ 1, 0 ≦ o ′ ≦ 0.3, and m ′ + n ′ ≠ 0, and 2m ′ + 2n ′ + (valence of M ⁸ ) × o ′ = 2 Indicates the number that satisfies
And sodium-based polyanion particles (E) on the surface of which carbon (c) is supported, and sodium complex oxide particles.
Peak intensity ratio ((peak intensity of Ni2p _3/2 ) / (peak intensity of P2p + peak intensity of C1s) by X-ray photoelectron spectroscopy (XPS) is more than 0.05 and less than 0.4 The present invention provides a battery positive electrode active material.

  Furthermore, according to the present invention, layered lithium composite oxide secondary particles (A) and lithium-based polyanion particles (B) having carbon (c) supported on the surface are mixed while applying compressive force and shear force. The present invention also provides a method of producing the above-mentioned positive electrode active material for a lithium ion secondary battery, which comprises the step of complexing.

  In the present invention, layered sodium complex oxide secondary particles (D) and sodium-based polyanion particles (E) formed by supporting carbon (c) on the surface are mixed while applying compressive force and shear force. The present invention also provides a method of producing the above-mentioned positive electrode active material for a lithium ion secondary battery, which comprises the step of complexing.

  According to the positive electrode active material for a lithium ion secondary battery or the positive electrode active material for a sodium ion secondary battery of the present invention, while using a layered composite oxide, viscosity increase with time is suppressed and stable workability is achieved. It becomes possible to prepare the provided positive electrode slurry, and in the obtained lithium ion secondary battery or sodium ion secondary battery, both excellent discharge characteristics and safety can be achieved.

Hereinafter, the present invention will be described in detail.
The positive electrode active material for a lithium ion secondary battery of the present invention has the following formula (I):
LiNi _a Co _b Mn _c M ¹ _x O ₂ (I)
(In the formula (I), M ¹ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, And one or more elements selected from Bi and Ge, a, b, c, x, 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number satisfying 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + (valence of M ¹ ) × x = 3)
Or, the following formula (II):
LiNi _d Co _e Al _f M ² _y O ₂ (II)
(Wherein M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and D represents one or more elements selected from Ge, d, e, f and y each satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ It shows a number satisfying y ≦ 0.3 and 3d + 3e + 3f + (valence of M ² ) × y = 3)
In part of the surface of the layered lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (V):
LiCo _g M ⁵ _i PO ₄ (V)
(In the formula (V), M ⁵ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G and i satisfy 0 <g ≦ 1 , 0 ≦ i ≦ 0.3, and 2 g + (number of valences of M ⁵ ) × i = 2.
Or, the following formula (VI):
LiFe _m Mn _n M ⁶ _o PO ₄ (VI)
(In the formula (VI), M ⁶ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ⁶ ) × o = 2 is satisfied.)
And lithium complex polyanion particles (B) formed by supporting carbon (c) on the surface, and lithium complex oxide particles are complexed,
The peak intensity ratio ((peak intensity of Ni2p3 _{/ 2} ) / (peak intensity of P2p + peak intensity of C1s)) by X-ray photoelectron spectroscopy (XPS) is more than 0.05 and less than 0.4.

Moreover, the positive electrode active material for a sodium ion secondary battery of the present invention has the following formula (III):
NaNi _{a '} Co _b' Mn _{c '} M ³ _x' O ₂ (III)
(Wherein M ³ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, A ', b', c 'and x' each represents 0.3 ≦ a ′ <1, 0 <b ′ ≦ 0.7, 0 <a c ′ ≦ 0.7, 0 ≦ x ′ ≦ 0.3, and 3a ′ + 3b ′ + 3c ′ + (valence number of M ³ ) × x ′ = 3.
Or, the following formula (IV):
NaNi _d' Co _{e '} Al _f' M ⁴ _{y '} O ₂ (IV)
(Wherein, in the formula (IV), M ⁴ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and And d ′, e ′, f ′ and y ′ each represent 0.4 ≦ d ′ <1, 0 <e ′ ≦ 0.6, 0 <f ′.数 0.3, 0 y y '0.3 0.3, and 3d' + 3e '+ 3f' + (valence number of M ⁴ ) x y '= 3 is satisfied.)
In part of the surface of the layered sodium complex oxide secondary particles (D) consisting of sodium complex oxide particles represented by the following formula (VII):
NaCo _{g '} M ⁷ _i' PO ₄ ... (VII)
(In the formula (VII), M ⁷ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G ′ and i ′ satisfy 0 <g '0 1, 0 i i' 2 0.3, and 2g '+ (valence number of M ⁷ ) = 2i' = 2 is satisfied),
Or the following formula (VIII):
NaFe _{m '} Mn _n' M ⁸ _{o '} PO ₄ ... (VIII)
(In the formula (VIII), M ⁸ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M ′, n ′, and o ′ are 0 ≦ m ′ ≦ 1, 0 ≦ n ′ ≦ 1, 0 ≦ o ′ ≦ 0.3, and m ′ + n ′ ≠ 0, and 2m ′ + 2n ′ + (valence of M ⁸ ) × o ′ = 2 Indicates the number that satisfies
And sodium-based polyanion particles (E) on the surface of which carbon (c) is supported, and sodium complex oxide particles.
The peak intensity ratio ((peak intensity of Ni2p3 _{/ 2} ) / (peak intensity of P2p + peak intensity of C1s)) by X-ray photoelectron spectroscopy (XPS) is more than 0.05 and less than 0.4.

Layered lithium composite oxide composed of lithium composite oxide particles represented by the above formula (I) (so-called Li-Ni-Co-Mn oxide, hereinafter referred to as "Li-NCM composite oxide") Layered sodium composite oxide (so-called Na-Ni-Co-Mn oxide) comprising secondary particles (A) and sodium composite oxide particles represented by the above-mentioned formula (III), hereinafter “Na-NCM system Li-NCM-based composite oxide and Na-NCM-based composite oxide are collectively referred to as “NCM-based composite oxide.” Secondary particles (D), and the above-mentioned formula (II) Layered lithium composite oxide composed of lithium composite oxide particles (so-called Li-Ni-Co-Al oxide, hereinafter referred to as "Li-NCA composite oxide") secondary particles (A) And the above formula (IV A layered sodium complex oxide (so-called Na-Ni-Co-Al oxide, which is hereinafter referred to as "Na-NCA complex oxide") composed of sodium complex oxide particles represented by The composite oxide and the Na-NCA composite oxide are collectively referred to as “NCA composite oxide”.) The secondary particles (D) are both particles having a layered rock salt structure.

M ¹ in the above formula (I) or M ³ in the above formula (III) is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr Or one or more elements selected from Sn, Ta, W, La, Ce, Pb, Bi and Ge.
In the above formula (I), a, b, c and x are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, 0 ≦ x ≦ 0.3, And 3a + 3b + 3c + (valence number of M ¹ ) × x = 3, and a ′, b ′, c ′, x ′ in the above formula (III) satisfy 0.3 ≦ a ′ <1, 0 < b ′ ≦ 0.7, 0 <c ′ ≦ 0.7, 0 ≦ x ′ ≦ 0.3, and a number satisfying 3a ′ + 3b ′ + 3c ′ + (valence of M ³ ) × x ′ = 3 .

In the NCM-based composite oxide represented by the above formula (I) or formula (III), Ni, Co and Mn are known to be excellent in electron conductivity and to contribute to battery capacity and output characteristics. Further, from the viewpoint of cycle characteristics, it is preferable that a part of the transition element is substituted by another metal element M ¹ or M ³ . By substituting the metal element M ¹ or M ³ , the crystal structure of the NCM composite oxide represented by the formula (I) or the formula (III) is stabilized. It is considered that the collapse of the crystal structure can be suppressed even if the discharge is repeated, and a high discharge capacity can be secured.
Specific examples of the Li-NCM composite oxide represented by the above formula (I) include LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.2 Co _0.4 Mn _0.4 O ₂ , LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O ₂ , and LiNi _0.33 Co _0.31 Mn _0.33 Zn _0.03 O _{2 and the} like. Among them, when the discharge capacity is more important, a composition with a large amount of Ni such as LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ is preferable, and when the cycle characteristics are more important, A composition with a small amount of Ni, such as LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O ₂ is preferable.
Specific examples of the Na-NCM composite oxide represented by the above formula (III) include NaNi _0.33 Co _0.33 Mn _0.34 O ₂ , NaNi _0.8 Co _0.1 Mn _0.1 O ₂ , and NaNi _0.6 Co _0.2 Mn. _0.2 O ₂ , NaNi _0.2 Co _0.4 Mn _0.4 O ₂ , NaNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O ₂ , and NaNi _0.33 Co _0.31 Mn _0.33 Zn _0.03 O _{2 and the} like can be mentioned. Above all, a composition with a large amount of Ni such as NaNi _0.8 Co _0.1 Mn _0.1 O ₂ or NaNi _0.6 Co _0.2 Mn _0.2 O ₂ is preferable when the discharge capacity is more important, and when the cycle characteristic is more important, A composition with a small amount of Ni, such as NaNi _0.33 Co _0.33 Mn _0.34 O ₂ , NaNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O ₂ is preferable.

The average particle size of the primary particles of the NCM composite oxide represented by the above formula (I) or formula (III) is preferably 500 nm or less, more preferably 300 nm or less. Thus, by setting the average particle diameter of the primary particles of the NCM composite oxide to at least 500 nm or less, the amount of expansion and contraction of the primary particles accompanying the insertion and detachment of lithium ions or sodium ions can be suppressed. And particle cracking can be effectively prevented. The lower limit of the average particle diameter of the primary particles is not particularly limited, but is preferably 50 nm or more from the viewpoint of handling.
The average particle diameter of the NCM-based composite oxide secondary particles (A) or (D) formed by the aggregation of the primary particles is preferably 25 μm or less, more preferably 20 μm or less. When the average particle diameter of the secondary particles is 25 μm or less, a positive electrode slurry having good uniformity of the coating thickness on the current collector can be easily prepared. The lower limit of the average particle diameter of the secondary particles is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, from the viewpoint of handling.
Here, the average particle size means an average value of measured values of particle sizes (length of major axis) of several tens of particles in observation with an electron microscope of SEM or TEM.

  In the present specification, the NCM-based composite oxide secondary particles (A) or (D) include only primary particles formed by forming the respective secondary particles, and lithium-based polyanion particles (B) or sodium-based particles. It does not contain polyanion particles (E).

  In fact, the NCM-based composite oxide secondary particles (A) or (D) have voids formed between primary particles, but the NCM-based composite oxide secondary particles (A) or (D) Since the interparticle space is narrowed in the production of the present invention, the space possessed by the NCM-based composite oxide secondary particles (A) or (D) is a lithium-based polyanion particle (B) or a sodium-based polyanion particle (E). It does not have a size that can penetrate inside.

Next, the Li-NCA composite oxide represented by the formula (II) and the Na-NCA composite oxide represented by the formula (IV) will be described.
M ² in the above formula (II) or M ⁴ in the above formula (IV) is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn Or one or more elements selected from Ta, W, La, Ce, Pb, Bi and Ge.
Further, d, e, f and y in the above formula (II) satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ y ≦ 0.3, And 3d + 3e + 3f + (valence of M ² ) × y = 3, and d ′, e ′, f ′, y ′ in the above formula (IV) satisfy 0.4 ≦ d ′ <1, 0 < e ′ ≦ 0.6, 0 <f ′ ≦ 0.3, 0 ≦ y ′ ≦ 0.3, and 3d ′ + 3e ′ + 3f ′ + (valence of M ⁴ ) × y ′ = 3 .

The NCA-based composite oxide represented by the above formula (II) or formula (IV) has a discharge in the secondary battery obtained further than the NCM-based composite oxide represented by formula (I) or formula (III) Excellent in capacity and output characteristics. In addition, due to the content of Al, deterioration due to moisture in the atmosphere is unlikely to occur, and the safety is also excellent.
Specific examples of the Li-NCA composite oxide represented by the above formula (II) include LiNi _0.33 Co _0.33 Al _0.34 O ₂ , LiNi _0.8 Co _0.1 Al _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ , LiNi _0.8 Co _0.15 Al _0.03 Zn _0.03 O _{2 and the} like can be mentioned. Among these, LiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ is preferable.
Specific examples of the Na-NCA composite oxide represented by the above formula (IV) include NaNi _0.33 Co _0.33 Al _0.34 O ₂ , NaNi _0.8 Co _0.1 Al _0.1 O ₂ , NaNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ , NaNi _0.8 Co _0.15 Al _0.03 Zn _0.03 O _{2 and the} like can be mentioned. Among these, NaiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ is preferable.

  Average particle diameter of primary particles of the NCA composite oxide represented by the above formula (II) or formula (IV), and NCA composite oxide secondary particles (A) formed by aggregation of the primary particles or The average particle size of (D) is the same as that of the NCM-based composite oxide described above. That is, the average particle size of the primary particles of the NCA composite oxide represented by the above formula (II) or formula (IV) is preferably 500 nm or less, more preferably 300 nm or less, and composed of the above primary particles The average particle diameter of the NCA composite oxide secondary particles (A) or (D) is preferably 25 μm or less, more preferably 20 μm or less.

  The layered lithium composite oxide secondary particles (A) in the present invention are the Li-NCM composite oxide represented by the above formula (I) and the Li-NCA composite oxide represented by the above formula (II) May be mixed. The mixed state is a state in which the primary particles of the Li-NCM composite oxide represented by the above formula (I) and the primary particles of the Li-NCA composite oxide represented by the above formula (II) coexist Secondary particles may be formed, and secondary particles consisting only of the Li-NCM composite oxide represented by the above formula (I) and only Li-NCA composite oxide represented by the above formula (II) And secondary particles comprising the above, and further, primary particles of the Li-NCM composite oxide represented by the above-mentioned formula (I) and Li-NCA composite oxide represented by the above-mentioned formula (II) Secondary particles formed by the coexistence of primary particles of a secondary substance, secondary particles consisting only of the Li-NCM composite oxide represented by the above formula (I), and Li-NCA composite represented by the above formula (II) It may be mixed with secondary particles consisting only of oxides.

  The layered sodium complex oxide secondary particles (D) of the present invention are the Na-NCM complex oxide represented by the above formula (III) and the Na-NCA complex represented by the above formula (IV) Oxides may be mixed. The mixed state is a state in which the primary particles of the Na-NCM composite oxide represented by the formula (III) and the primary particles of the Na-NCA composite oxide represented by the formula (IV) coexist Secondary particles may be formed, and secondary particles consisting only of the Na-NCM composite oxide represented by the above formula (III) and only Na-NCA composite oxide represented by the above formula (IV) And secondary particles made of Ni, and further, primary particles of the Na-NCM composite oxide represented by the above-mentioned formula (III) and Na-NCA composite oxide represented by the above-mentioned formula (IV) Secondary particles formed by the coexistence of primary particles of a secondary substance, secondary particles consisting only of the Na-NCM composite oxide represented by the above formula (III), and Na-NCA composite represented by the above formula (IV) It may be mixed with secondary particles consisting only of oxides.

  NCM-based composite when NCM-based composite oxide represented by the above formula (I) or the above-mentioned formula (III) and NCA-based composite oxide represented by the above-mentioned formula (II) or the above-mentioned formula (IV) The proportion (mass%) of the oxide and the NCA composite oxide may be appropriately adjusted according to the desired battery characteristics. For example, when importance is attached to rate characteristics, it is preferable to increase the ratio of the NCM-based composite oxide represented by the above formula (I) or the above-mentioned formula (III), specifically, NCM-based composite oxidation It is preferable that it is a mass ratio (NCM type | system | group complex oxide: NCA type | system | group complex oxide) = 99.9: 0.1-60: 40 of a substance and NCA type complex oxide. In addition, for example, when more emphasis is placed on the discharge capacity, it is preferable to increase the ratio of the NCA composite oxide represented by the above formula (II) or the above formula (IV), specifically, for example, NCM It is preferable that it is mass ratio (NCM type | system | group complex oxide: NCA type | system | group complex oxide) = 40: 60-0.1: 99.9 of system complex oxide and NCA system complex oxide.

Next, the lithium-based polyanion particles (B) and the sodium-based polyanion particles (E) will be described.
The lithium-based polyanion particles (B) formed by complexing with lithium composite oxide particles only in part of the surface of the layered lithium composite oxide secondary particles (A) have the following formula (V):
LiCo _g M ⁵ _i PO ₄ (V)
(In the formula (V), M ⁵ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G and i satisfy 0 <g ≦ 1 , 0 ≦ i ≦ 0.3, and 2 g + (number of valences of M ⁵ ) × i = 2.
Or, the following formula (VI):
LiFe _m Mn _n M ⁶ _o PO ₄ (VI)
(In the formula (VI), M ⁶ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ⁶ ) × o = 2 is satisfied.)
And a compound capable of providing good lithium ion conductivity. Furthermore, in the lithium-based polyanion particles (B) represented by the above formula (V) or the formula (VI), carbon (c) is supported on the particle surface, and the carbon (c) is derived from cellulose nanofibers It may be carbon (c1) or carbon (c2) derived from a water-soluble carbon material.

Specific examples of the lithium-based polyanion particles (B) represented by the above formula (V) include LiCoPO ₄ and LiCo _0.25 Fe _0.25 PO ₄ .
In addition, as the lithium-based polyanion particles (B) represented by the above formula (VI), 0.5 ≦ n ≦ 1 is preferable from the viewpoint of the average discharge voltage of the positive electrode active material for lithium ion secondary batteries. 6 ≦ n ≦ 1 is more preferable, and 0.65 ≦ n ≦ 1 is more preferable. Specifically, for example, LiMnPO ₄ , LiMn _0.9 Fe _0.1 PO ₄ , LiMn _0.8 Fe _0.2 PO ₄ , LiMn _0.75 Fe _0.15 Mg _0.1 PO ₄ , LiMn _0.75 Fe _0.19 Zr _0.03 PO ₄ , LiMn _0.7 Fe _0.3 PO ₄ , LiMn _0.6 Fe _0.4 PO ₄ , LiMn _0.5 Fe _0.5 PO _{4 and the} like are mentioned, and among them, LiMn _0.8 Fe _0.2 PO ₄ is preferable.

  The average particle diameter of the lithium-based polyanion particles (B) represented by the formula (V) or the formula (VI) is the same as that of the lithium composite oxide particles on the surface of the layered lithium composite oxide secondary particles (A). It is preferably 20 to 200 nm from the viewpoint of complexation to Specifically, when the lithium-based polyanion particle (B) is represented by the formula (V), it is more preferably 20 to 200 nm, still more preferably 25 to 180 nm, and still more preferably 30 to 170 nm. It is. Moreover, when lithium type polyanion particle | grain (B) is represented by Formula (VI), More preferably, it is 50-200 nm, More preferably, it is 70-150 nm.

The lithium ion conductivity of the lithium-based polyanion particles (B) represented by the above formula (V) or (VI) at a pressure of 20 MPa at 25 ° C. is 1 × 10 ⁻⁷ S / cm or more Preferably, it is more preferably 1 × 10 ⁻⁶ S / cm or more. The upper limit value of the lithium ion conductivity of the lithium-based polyanion particles (B) is not particularly limited.

  The lithium-based polyanion particles (B) represented by the above formula (V) or formula (VI) are a composite of a lithium composite oxide as a primary particle constituting the layered lithium composite oxide secondary particles (A) And may be directly complexed with part of the layered lithium composite oxide secondary particles (A) formed by aggregation of primary particles of the lithium composite oxide.

  The lithium-based polyanion particles (B) have carbon (c) supported on the surface thereof. The amount of carbon (c) supported is preferably 0.1% by mass or more and less than 5% by mass in 100% by mass of the lithium-based polyanion particles (B) on which the carbon (c) is supported. Specifically, when the lithium-based polyanion particles (B) are represented by the formula (V), the total amount of lithium-based polyanion particles (B) on which carbon (c) is supported is preferably 100% by mass, It is 0.5-5 mass%, More preferably, it is 1-5 mass%, More preferably, it is 1-4 mass%. When the lithium-based polyanion particles (B) are represented by the formula (VI), the amount of the lithium-based polyanion particles (B) supported by carbon (c) is preferably 100% by mass, preferably 0.1. More than 4% by mass, more preferably 0.1 to 3% by mass, and still more preferably 0.1 to 2% by mass.

  Content of layered lithium composite oxide secondary particles (A), content of lithium-based polyanion particles (B) having carbon (c) supported on the surface (including supported amount of carbon (c)) The mass ratio of (A) :( B) is preferably 95: 5 to 50:50, more preferably 90:10 to 50:50, and still more preferably 90:10 to 60:40. is there.

  On the surface of the layered lithium complex oxide secondary particles (A) in the present invention, the lithium-based polyanion particles (B) are complexed so as to cover only a part of the surface of such secondary particles. Thereby, when the positive electrode slurry is formed, although the reason is not clear, it is possible to effectively and efficiently suppress the increase in viscosity of the slurry with time without covering the entire surface of the secondary particles. .

The state in which the lithium-based polyanion particles (B) cover only a part of the surface of the layered lithium complex oxide secondary particles (A) is the peak intensity ratio ((Ni ₂ p ₃ ) measured by X-ray photoelectron spectroscopy (XPS) _{/ 2} peak intensity) / (P2p peak intensity + C1s peak intensity)), that is, the peak intensity of Ni2p _3/2 released from the layered lithium complex oxide secondary particles (A), and lithium-based polyanion particles ((2) This can be confirmed by the value of the ratio of the peak intensities of P2p and C1s released from B). Specifically, when the obtained positive electrode active material for a lithium ion secondary battery is irradiated with soft X-rays of several keV, the energy specific to the element constituting the part from the part irradiated with such soft X-rays Since photoelectrons having a value are emitted, the peak intensity corresponding to trivalent Ni obtained by analyzing the peak of Ni.sub.2p _3/2 released from the layered lithium complex oxide secondary particles (A) and lithium The area ratio of the material serving as the surface of the positive electrode active material for a lithium ion secondary battery by comparing the sum of the peak intensities of P2p and C1s released from the polyanion particles (B), that is, such a lithium polyanion The extent to which the particles (B) coat the layered lithium complex oxide secondary particles (A) can be seen.

More specifically, the positive electrode active material for a lithium ion secondary battery in the present invention has a viewpoint of suppressing an increase in viscosity of the positive electrode slurry with time, and further ensures excellent discharge characteristics and safety in the obtained secondary battery. From the point of view, the peak intensity ratio by this XPS ((peak intensity of Ni2p _3/2 ) / (peak intensity of P2p + peak intensity of C1s)) is more than 0.05 and less than 0.4, preferably 0 More than 0.05 and 0.37 or less, more preferably more than 0.05 and 0.35 or less.

The surface coverage of the layered lithium complex oxide secondary particles (A) by the lithium-based polyanion particles (B) can also be determined from the value of the ratio of the peak intensities. Specifically, when all of the surface of the layered lithium composite oxide secondary particles (A) is covered with the lithium-based polyanion particles (B) (surface coverage 100 area%), the XPS peak intensity ratio and the layered Peak intensity ratio of the secondary lithium composite oxide secondary particles (A) alone (surface coverage 0 area%) is determined, and a relational expression of surface coverage and XPS peak intensity ratio is determined so as to connect these two points. .
Then, the surface coverage (area%) by the lithium-based polyanion particles (B) may be determined from the measurement result of the XPS peak intensity ratio of an arbitrary positive electrode active material for secondary battery using the above relational expression.
An example of the said relational expression is shown to following formula (1).
Surface coverage (area%) of secondary lithium secondary oxide particles (A) by lithium-based polyanion particles (B) =
-208.3 x (XPS peak intensity ratio) + 104.2 (1)

  For example, the surface coverage of the layered lithium complex oxide secondary particles (A) with lithium-based polyanion particles (B) determined by the above formula (1) is preferably a value corresponding to the peak intensity ratio by the above-mentioned XPS More than 20 area% and less than 95 area%, more preferably more than 20 area% and less than 90 area%, and still more preferably more than 20 area% and less than 84 area%.

In addition, sodium-based polyanion particles (E) formed by complexing with sodium complex oxide particles only in part of the surface of layered sodium complex oxide secondary particles (D) have the following formula (VII):
NaCo _{g '} M ⁷ _i' PO ₄ ... (VII)
(In the formula (VII), M ⁷ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G ′ and i ′ satisfy 0 <g '0 1, 0 i i' 2 0.3, and 2g '+ (valence number of M ⁷ ) = 2i' = 2 is satisfied),
Or the following formula (VIII):
NaFe _{m '} Mn _n' M ⁸ _{o '} PO ₄ ... (VIII)
(In the formula (VIII), M ⁸ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M ′, n ′, and o ′ are 0 ≦ m ′ ≦ 1, 0 ≦ n ′ ≦ 1, 0 ≦ o ′ ≦ 0.3, and m ′ + n ′ ≠ 0, and 2m ′ + 2n ′ + (valence of M ⁸ ) × o ′ = 2 Indicates the number that satisfies
And are compounds capable of providing good sodium ion conductivity. Furthermore, sodium-based polyanion particles (E) represented by the above formula (VII) or formula (VIII) are obtained by supporting carbon (c) on the particle surface, and such carbon (c) is derived from cellulose nanofibers It may be carbon (c1) or carbon (c2) derived from a water-soluble carbon material.

Specific examples of the sodium-based polyanion particles (E) represented by the above formula (VII) include NaCoPO ₄ , NaCo _0.25 Fe _0.25 PO _{4 and the} like.
Further, as sodium-based polyanion particles (E) represented by the above formula (VIII), specifically, for example, NaFe _0.2 Mn _0.8 PO ₄ , NaFe _0.9 Mn _0.1 PO ₄ , NaFe _0.15 Mn _0.75 Mg _0.1 PO ₄ , naFe _0.19 Mn _0.75 Zr _0.03 PO ₄ and the like, among naFe _0.2 Mn _0.8 PO ₄ are preferred.

  The average particle diameter of the sodium-based polyanion particles (E) represented by the above formula (VII) or (VIII) is intimately composited with the sodium composite oxide particles on the surface of the sodium composite oxide secondary particles (D) Preferably, it is 50 to 200 nm, more preferably 70 to 150 nm.

The sodium ion conductivity of the sodium-based polyanion particles (E) represented by the above formula (VII) or (VIII) at a pressure of 20 MPa at 25 ° C. is 1 × 10 ⁻⁷ S / cm or more Preferably, it is more preferably 1 × 10 ⁻⁶ S / cm or more. The upper limit value of the lithium ion conductivity of the sodium-based polyanion particles (E) is not particularly limited.

  The sodium-based polyanion particle (E) represented by the above formula (VII) or (VIII) is a complex with the sodium complex oxide as a primary particle constituting the layered sodium complex oxide secondary particle (D). And may be directly complexed with a part of sodium composite oxide secondary particles (D) formed by aggregation of primary particles of sodium composite oxide.

  The sodium-based polyanion particles (E) have carbon (c) supported on the surface thereof. The amount of carbon (c) supported is preferably 0.1% by mass or more and less than 5% by mass in 100% by mass of the total amount of sodium-based polyanion particles (E) on which carbon (c) is supported, more preferably Is 0.5 to 5% by mass, and more preferably 1 to 5% by mass.

  The mass of the content of sodium composite oxide secondary particles (D) and the content of sodium-based polyanion particles (E) having carbon (c) supported on the surface (including the amount of carbon (c) supported) The ratio ((D) :( E)) is preferably 95: 5 to 50:50, more preferably 90:10 to 50:50, and still more preferably 90:10 to 60:40.

  On the surface of the layered sodium complex oxide secondary particles (D) in the present invention, sodium-based polyanion particles (E) are complexed so as to cover only a part of the surface of such secondary particles. Thereby, when the positive electrode slurry is formed, although the reason is not clear, it is possible to effectively and efficiently suppress the increase in viscosity of the slurry with time without covering the entire surface of the secondary particles. .

The state in which the sodium-based polyanion particles (E) cover only a part of the surface of the layered-type sodium composite oxide secondary particles (D) is the same as the lithium-based polyanion particles (B) in the layered-type lithium composite oxide secondary The peak intensity ratio according to X-ray photoelectron spectroscopy (XPS) ((peak intensity of Ni2p _3/2 ) / (peak intensity of P2p + C1s) as in the case of covering only a part of the surface of the particle (A) Peak intensities of Ni2p _3/2 released from layered sodium complex oxide secondary particles (D) and peak intensities of P2p and C1s released from sodium-based polyanion particles (E)). It can confirm by the value of ratio.
Specifically, the positive electrode active material for a sodium ion secondary battery in the present invention is from the viewpoint of suppressing the increase in viscosity of the positive electrode slurry, and from the viewpoint of securing excellent discharge characteristics and safety in the obtained secondary battery. The peak intensity ratio by this XPS ((peak intensity of Ni2p _3/2 ) / (peak intensity of P2p + peak intensity of C1s)) is more than 0.05 and less than 0.4, preferably more than 0.05 It is 0.37 or less, more preferably more than 0.05 and 0.35 or less.

The surface coverage of the layered sodium complex oxide secondary particles (D) by the sodium-based polyanion particles (E) is the same as that of the layered lithium complex oxide secondary particles (A) by the lithium-based polyanion particles (B). It can be determined in the same manner as the surface coverage.
Specifically, for example, the surface coverage of the layered sodium complex oxide secondary particles (D) by sodium-based polyanion particles (E) obtained by the same method as the method using the above-mentioned formula (1) is preferably More than 20 area% and less than 95 area%, more preferably more than 20 area% and less than 90 area%, and still more preferably more than 20 area% and less than 84 area%.

  The above-mentioned cellulose nanofibers serving as a carbon source (c1), which may be supported as carbon (c) on the surface of lithium-based polyanion particles (B) or sodium-based polyanion particles (E), are all plants It is a skeletal component that occupies about 50% of the cell wall, and is a lightweight high-strength fiber that can be obtained by disentanglement etc. of plant fibers that make up the cell wall to nanosize, and carbon from cellulose nanofibers (c1) Has a periodic structure. The fiber diameter of such cellulose nanofibers is 1 nm to 100 nm, and also has good dispersibility in water. Further, in the cellulose molecular chain constituting the cellulose nanofiber, a periodic structure is formed by carbon, and while carbonized, it combines with the polyanion particles to form the lithium-based polyanion particles (B) or the sodium-based polyanion particles ( A positive electrode active material for a lithium ion secondary battery or a positive electrode active material for a sodium ion secondary battery, which imparts electron conductivity to these polyanion particles by being firmly supported on the surface of E) and is excellent in cycle characteristics You can get it.

  The water-soluble carbon material as the carbon source (c2), which may be supported as carbon (c) on the surface of the lithium-based polyanion particles (B) or the sodium-based polyanion particles (E), is 25 ° C. Means a carbon material that dissolves at least 0.4 g, preferably at least 1.0 g, in terms of carbon atom of the water-soluble carbon material in 100 g of water, and carbonizing the above lithium-based polyanion particles (B) or It will be present on the surface of sodium-based polyanion particles (E). Examples of such a water-soluble carbon material include one or more selected from saccharides, polyols, polyethers, and organic acids. More specifically, for example, monosaccharides such as glucose, fructose, galactose and mannose; disaccharides such as maltose, sucrose and cellobiose; polysaccharides such as starch and dextrin; ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, butane And polyols and polyethers such as diol, propanediol, polyvinyl alcohol and glycerin; and organic acids such as citric acid, tartaric acid and ascorbic acid. Among them, glucose, fructose, sucrose and dextrin are preferable, and glucose is more preferable, from the viewpoint of enhancing the solubility in a solvent and the dispersibility to effectively function as a carbon material.

  The atom of carbon (c1) derived from cellulose nanofibers or carbon (c2) derived from a water-soluble carbon material, which is present as carbon (c) on the surface of lithium-based polyanion particles (B) or sodium-based polyanion particles (E) The converted amount (the amount of carbon supported) can be confirmed as the amount of carbon measured using a carbon / sulfur analyzer for lithium-based polyanion particles (B) or sodium-based polyanion particles (E).

  The method for producing a positive electrode active material for a lithium ion secondary battery of the present invention comprises a layered lithium complex oxide secondary particle (A) and a lithium-based polyanion particle (B) formed by supporting carbon (c) on the surface. And a process of mixing and compounding while applying a compressive force and a shear force. Further, the method for producing a positive electrode active material for a sodium ion secondary battery of the present invention comprises a layered sodium complex oxide secondary particle (D) and a sodium-based polyanion particle (E) having carbon (c) supported on the surface thereof. ) May be mixed and compounded while applying compressive force and shear force.

  In the present invention, the layer type lithium complex oxide secondary particles (A) and the lithium type polyanion particles (B) are complexed, or the layer type sodium complex oxide secondary particles (D) and the sodium type polyanion are used. In the particles (E), water-insoluble carbon powder (c3) other than cellulose nanofiber-derived carbon (c1) is simultaneously mixed as a carbon source, and the water-insoluble carbon powder (c3) is mixed with the layered lithium complex oxide secondary It may be complexed with the particle (A) and the lithium-based polyanion particle (B), or may be complexed with the layered sodium complex oxide secondary particle (D) and the sodium-based polyanion particle (E). The water-insoluble carbon powder (c3) is a carbon material different from the carbon (c2) derived from the water-soluble carbon material, and is water insoluble (25 ° C. water) other than the cellulose nanofiber-derived carbon (c1) The amount of dissolution per 100 g is a carbon powder having a conductivity of less than 0.4 g in terms of carbon atom of the water-insoluble carbon powder (c3). Without complexing the water-insoluble carbon powder (c3), the discharge characteristics of the positive electrode active material for a lithium ion secondary battery or the positive electrode active material for a sodium ion secondary battery of the present invention do not deteriorate. A plurality of layers on the surface of the positive electrode active material for a lithium ion secondary battery, or in the gap between the layered lithium complex oxide secondary particles (A) and the lithium polyanion particles (B) in the positive electrode active material for a lithium ion secondary battery Present so as to cover the lithium-based polyanion particles (B) or intervene in the gap between the layered sodium complex oxide secondary particles (D) and the sodium-based polyanion particles (E) in the positive electrode active material for sodium ion secondary batteries, Or while being present so as to cover a plurality of sodium-based polyanion particles (E) on the surface of the positive electrode active material for a sodium ion secondary battery, The degree of complexation of these is made stronger, and the lithium-based polyanion particles (B) are exfoliated from the layered lithium composite oxide secondary particles (A), or the layered sodium composite oxide secondary particles (D) Exfoliation of the sodium-based polyanion particles (E) from the above can be effectively suppressed.

  Examples of the water-insoluble carbon powder (c3) include graphite, amorphous carbon (such as ketjen black and acetylene black), nanocarbon (such as graphene and fullerene), conductive polymer powder (polyaniline powder, polyacetylene powder, polythiophene powder) And polypyrrole powder etc. 1) or 2 or more types are mentioned. In particular, the degree of complexing of the layered lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) or the layered sodium composite oxide secondary particles (D) to the sodium-based polyanion particles (E) From the viewpoint of reinforcement, graphite, acetylene black, graphene, and polyaniline powder are preferable, and graphite is more preferable. The graphite may be any of artificial graphite (scale, bulk, earth, graphene) and natural graphite.

  The average particle size of the water-insoluble carbon powder (c3) is preferably 0.5 to 20 μm, more preferably 1.0 to 15 μm, from the viewpoint of complexation.

  In the positive electrode active material for a lithium ion secondary battery of the present invention, the water mixed and mixed simultaneously with the layered lithium complex oxide secondary particles (A) and the lithium-based polyanion particles (B) in the complexing process The content of the insoluble carbon powder (c3) is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass in total of the layered lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). More preferably, it is 1-8 mass parts, More preferably, it is 1-5 mass parts.

  Furthermore, the total amount of lithium-based polyanion particles (B) on which the above-mentioned layered lithium complex oxide secondary particles (A) and carbon (c) are supported, and carbon carried on the lithium-based polyanion particles (B) The mass ratio (((A) + (B)): ((c) + (c3))) to the total content of (c) and the water-insoluble carbon powder (c3) is preferably 99.5: 0. It is 5-90: 10, More preferably, it is 99: 1-92: 8, More preferably, it is 99: 1-95: 5.

  In the positive electrode active material for a sodium ion secondary battery of the present invention, the layered sodium complex oxide secondary particles (D) and the sodium-based polyanion particles (E) are simultaneously mixed and complexed at the time of complexing. The content of the water-insoluble carbon powder (c3) is preferably 0.5 to 24 parts by mass with respect to 100 parts by mass of the total of the layered sodium complex oxide secondary particles (D) and the sodium-based polyanion particles (E). Sodium, more preferably 1 to 16 parts by mass, and still more preferably 1 to 10 parts by mass, wherein the layered sodium complex oxide secondary particles (D) and carbon (c) are supported. The mass ratio of the total amount of the polyanion particles (E) to the total content of the carbon (c) and the water-insoluble carbon powder (c3) supported on the sodium polyanion particles (E) ) + (E)): ((c) + (c3))) is preferably 99.5: 0.5 to 90:10, more preferably 99: 1 to 92: 8, still more preferably Is 99: 1 to 95: 5.

  Next, the method for producing a positive electrode active material for a lithium ion secondary battery or a positive electrode active material for a sodium ion secondary battery will be described more specifically.

The manufacturing method of the positive electrode active material for lithium ion secondary batteries or the positive electrode active material for sodium ion secondary batteries includes the following steps (X) to (Z):
(X) A mixed powder containing a lithium compound or a sodium compound, a nickel compound, a cobalt compound, and a manganese compound is calcined to obtain an NCM-based composite oxide secondary particle (A) of the formula (I) or the formula (III) Or get (D), or
A mixed powder containing a lithium compound or a sodium compound, a nickel compound, a cobalt compound, and an aluminum compound is calcined to form the NCA composite oxide secondary particles (A) or (D) of the formula (II) or the formula (IV). Step of obtaining
(Y) Lithium compound or sodium compound, and phosphoric acid compound, and further cobalt compound are subjected to a wet reaction to obtain lithium-based polyanion particles (B) or sodium-based polyanion particles (E), or
Subjecting the lithium compound or the sodium compound, the phosphoric acid compound, the iron compound and / or the manganese compound to a wet reaction to obtain a lithium-based polyanion particle (B) or a sodium-based polyanion particle (E),
(Z) A lithium-based polyanion particle obtained in the step (Y) to the NCM-based composite oxide secondary particle or the NCA-based composite oxide secondary particle (A) or (D) obtained in the step (X) (B) or sodium-based polyanion particles (E) are added and mixed while applying compressive force and shear force to form a complex, or NCM-based complex oxide 2 obtained in step (X) Lithium-based polyanion particles (B) or sodium-based polyanion particles (E) obtained in the step (Y), and a water-insoluble carbon powder (the following particles or NCA-based composite oxide secondary particles (A) or (D) c3) is added and mixed to give a composite while applying compressive force and shear force.

Step (X) calcinates the mixed powder containing lithium compound or sodium compound, nickel compound, cobalt compound, and manganese compound to obtain the NCM-based composite oxide secondary particles of formula (I) or formula (III) (A) or (D) is obtained, or a mixed powder containing a lithium compound or a sodium compound, a nickel compound, a cobalt compound, and an aluminum compound is fired to prepare an NCA system of the formula (II) or the formula (IV) It is a process of obtaining complex oxide secondary particles (A) or (D).
In the description of the step (X), the positive electrode active material for a lithium ion secondary battery represented by the above formula (I) or the formula (II) will be specifically described in order to avoid complication of the description. Regarding the method for producing a positive electrode active material for a sodium ion secondary battery represented by the above formula (III) or formula (IV), the wording of “lithium” in the method for producing a positive electrode active material for lithium ion secondary battery shown below It should be replaced with "sodium". In addition, the lithium-based polyanion particles (B) or the sodium-based polyanion particles (E) are also simply referred to as "polyanion particles".

In step (X), the mixed powder containing a lithium compound, a nickel compound, a cobalt compound, and a manganese compound is calcined to obtain NCM-based composite oxide secondary particles (A) of the formula (I), or In this step, the mixed powder containing a lithium compound, a nickel compound, a cobalt compound, and an aluminum compound is fired to obtain an NCA composite oxide secondary particle (A) of the formula (II).

In order to obtain the NCM-based composite oxide secondary particles (A), a raw material compound, for example, a nickel compound, a cobalt compound, and a manganese compound, is dissolved in water so as to have a desired composite oxide composition, and an aqueous solution A is obtained. Get Examples of the nickel compound, cobalt compound, and manganese compound include sulfates, nitrates, carbonates, acetates, oxalates, oxides, hydroxides, and halides of the metal element. Specific examples thereof include, but are not limited to, nickel sulfate, cobalt sulfate, manganese sulfate, nickel acetate, cobalt acetate, manganese acetate and the like.
In this process, Mg, Ti, Nb as a metal element for replacing a part of the layered lithium metal composite oxide that constitutes the active material so as to obtain a desired composite oxide composition as needed. At least one element selected from Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Ge It may be mixed.

  Next, an alkaline solution is added to the aqueous solution A to form an aqueous solution B, and the dissolved metal components are coprecipitated by the neutralization reaction to obtain a metal composite hydroxide. The alkali solution is added dropwise in an amount sufficient to keep the pH of the aqueous solution B at 10-14. As an alkaline solution, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia and the like can be used, but it is preferable to use sodium hydroxide, sodium carbonate or a mixed solution thereof.

  The aqueous solution B is stirred to form a metal composite hydroxide. The temperature of the aqueous solution B during this reaction is preferably 30 ° C. or higher, more preferably 30 to 60 ° C. Moreover, 30 minutes-120 minutes are preferable, and, as for the stirring time of the aqueous solution B, 30 to 60 minutes are more preferable.

  After stirring, the aqueous solution B is filtered to recover the metal composite hydroxide. The recovered metal composite hydroxide is preferably washed with water and then dried.

  Next, the metal composite hydroxide and the lithium compound are dry-mixed so as to have a desired composite oxide composition, and the mixture is fired under an oxygen atmosphere to obtain an NCM composite oxide. As a lithium compound, lithium hydroxide or its hydrate, lithium peroxide, lithium nitrate, lithium carbonate etc. can be used conveniently, for example. For dry mixing of the metal composite hydroxide and the lithium compound, a common dry mixer or mixing granulator such as a ball mill or a V blender can be used, and it is more preferable to use a planetary ball mill capable of self-revolution.

  The firing of the mixture of the metal composite hydroxide and the lithium compound is preferably performed in two steps (temporary firing and main firing). The NCM-based composite oxide can be efficiently obtained by performing main baking after removing by heating the decomposition components such as water molecules and carbon dioxide from hydroxide and carbonate in the above mixture. The conditions for the pre-sintering are not particularly limited, but the temperature rising rate is preferably 1 to 20 ° C./minute from room temperature. Further, the atmosphere is preferably an air atmosphere or an oxygen atmosphere. The firing temperature is preferably 700 ° C. to 1000 ° C., and more preferably 650 ° C. to 750 ° C. Furthermore, the baking time is preferably 3 to 20 hours, and more preferably 4 to 6 hours.

The conditions for the subsequent main firing are not particularly limited, but after the temporary firing, the temporary fired product crushed in a mortar or the like is heated again from room temperature at a temperature rising rate of 1 to 20 ° C./min. Be done. The atmosphere at this time is preferably an air atmosphere or an oxygen atmosphere. Moreover, it is preferable that it is 700 degreeC-1200 degreeC, and, as for a calcination temperature, it is more preferable that it is 750 degreeC-900 degreeC. Furthermore, the firing time is preferably 3 to 20 hours, and more preferably 8 to 10 hours.
For this two-step firing, use is made of an electric furnace, a rotary kiln, a tubular furnace, a pusher furnace, etc. adjusted to a gas atmosphere with an oxygen concentration of 20% by mass or more such as a dry air atmosphere subjected to dehumidifying and decarbonizing treatments. be able to.

  The average particle diameter of primary particles of the NCM composite oxide can be controlled by adjusting the firing temperature of the main firing. In order to set the average particle diameter of the primary particles of the NCM composite oxide to 50 nm to 500 nm, the firing temperature is preferably 700 ° C. to 1000 ° C., more preferably 750 ° C. to 900 ° C.

  Finally, the obtained calcined product is washed with water, filtered and dried to obtain NCM-based composite oxide secondary particles (A). Here, the above drying is performed in two steps, and the first step of drying is performed until the water content in the NCM-based composite oxide secondary particles (water content measured at a vaporization temperature of 300 ° C.) becomes 1 mass% or less. It is preferred to carry out the drying at a temperature of at most 120 ° C. after the drying of the second stage. The water content may be measured, for example, using a Karl Fischer moisture meter.

Next, the case of obtaining the NCA composite oxide secondary particles (A) in the step (X) will be specifically described.
In order to obtain the NCA composite oxide secondary particles (A), a raw material compound, for example, a nickel compound, a cobalt compound, and an aluminum compound, is dissolved in water so as to have a desired composite oxide composition, and an aqueous solution A is obtained. Get '. Examples of such nickel compounds, cobalt compounds, and aluminum compounds include sulfates, nitrates, carbonates, acetates, oxalates, oxides, hydroxides, and halides of the metal elements. Specific examples thereof include, but are not limited to, nickel sulfate, cobalt sulfate, aluminum sulfate, nickel acetate, cobalt acetate, aluminum acetate and the like. In this process, Mg, Ti, Nb as a metal element for replacing a part of the layered lithium metal composite oxide that constitutes the active material so as to obtain a desired composite oxide composition as needed. Mixed with one or more elements selected from Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Ge May be

  Next, an alkaline solution is added to the aqueous solution A 'to form an aqueous solution B', and the dissolved metal water is coprecipitated by the neutralization reaction to obtain a metal composite hydroxide. The alkali solution is added dropwise in an amount sufficient to maintain the pH of the aqueous solution B 'at 10-14. As the alkali solution, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia and the like can be used, but it is preferable to use ammonia, sodium hydroxide, sodium carbonate or a mixed solution thereof.

  The aqueous solution B 'is stirred to form a metal composite hydroxide. The temperature of the aqueous solution B' during this reaction is preferably 40C or higher, more preferably 40C to 60C. Moreover, 30 to 120 minutes are preferable and, as for the stirring time of aqueous solution B ', 30 to 60 minutes are more preferable.

  In order to obtain a metal composite hydroxide having a high bulk density, an oxidizing agent such as sodium hypochlorite or hydrogen peroxide water may be further added to the aqueous solution B 'after the reaction.

After stirring, the aqueous solution B ′ is filtered to recover the metal composite hydroxide. The recovered metal composite hydroxide is preferably fired to form a metal composite oxide. By reacting with the lithium compound as the metal complex oxide, the grade of the obtained NCA-based complex oxide is stabilized, and it can be reacted uniformly and sufficiently with lithium.
The firing conditions for obtaining the metal composite oxide are not particularly limited, and may be firing, for example, at a temperature of preferably 500 ° C. to 1100 ° C., more preferably 600 to 900 ° C. in an air atmosphere.

  Then, the metal complex oxide and the lithium compound are dry-mixed so as to have a desired composition of the complex oxide, and firing is performed under an oxygen atmosphere, whereby an NCA-based complex oxide can be obtained. The lithium compound is not particularly limited, and, for example, lithium hydroxide or a hydrate thereof, lithium peroxide, lithium nitrate, lithium carbonate and the like can be suitably used. For dry mixing of the metal complex oxide and the lithium compound, an ordinary dry mixer or mixing granulator such as a ball mill or V blender can be used, and for the baking, an oxygen atmosphere, dehumidification and decarbonization treatment are performed It is possible to use an electric furnace, a rotary kiln, a tubular furnace, a pusher furnace or the like adjusted to a gas atmosphere having an oxygen concentration of 20% by mass or more, such as a dry air atmosphere.

The firing temperature of the mixture of the metal complex oxide and the lithium compound is preferably 650 ° C. to 850 ° C., and more preferably 700 ° C. to 800 ° C. At a calcination temperature of less than 650 ° C., crystals of the obtained NCA composite oxide are undeveloped and structurally unstable, and their structure is easily destroyed by charge and discharge. On the other hand, when the firing temperature exceeds 850 ° C., the layered structure of the NCA composite oxide is broken, and insertion and desorption of lithium ions become difficult. The firing time is preferably 5 to 20 hours, and more preferably 6 to 10 hours.
Furthermore, in order to remove the crystal water or carbonic acid of the lithium compound, it is preferable to perform two-stage calcination similarly to the NCM-based composite oxide, in which case, the first-stage calcination is performed at 400 ° C. to 600 ° C. for 1 hour or more Then, the second baking may be performed at 650 ° C. to 850 ° C. for 5 hours or more.

Finally, the obtained calcined product is washed with water, filtered and dried to obtain NCA composite oxide secondary particles (A). 200-4000 g / L is preferable and, as for the slurry density | concentration at the time of water-washing baking products, 500-2000 g / L is more preferable. When the slurry concentration is less than 200 g / L, lithium is released from secondary particles of the NCA composite oxide.
In addition, if the water used for water washing contains a large amount of carbon dioxide gas, lithium carbonate will precipitate on the secondary particles of the NCA composite oxide, so the electric conductivity of water used for water washing is less than 10 μS / cm. Preferably, water of 1 μS / cm or less is more preferable.

  In the present invention, in this step (X), it is necessary to carry out drying performed after water washing and filtration in two steps. The drying of the first step is performed at 90 ° C. or less until the water content in the secondary particles (water content measured at the vaporization temperature of 300 ° C.) becomes 1 mass% or less, and then the drying of the second step is performed at 120 ° C. It does above.

In the step (Y) subsequent to the above step (X), the lithium compound or sodium compound, and the phosphoric acid compound, and further the cobalt compound are subjected to a wet reaction to obtain a lithium-based polyanion particle (B) or a sodium-based polyanion particle (E) Or lithium compounds, sodium compounds, phosphoric compounds, iron compounds and / or manganese compounds in a wet reaction to obtain lithium-based polyanion particles (B) or sodium-based polyanion particles (E). Is a process of obtaining
Hereinafter, in order to avoid complication of the description, the lithium-based polyanion particles (B) represented by the above-mentioned formula (VI) are obtained using an iron compound and a manganese compound as an example of the step (Y). This will be described specifically.
In addition, what is necessary is just to replace the wording of "iron compound and / or a manganese compound" in process (Y) with "cobalt compound", and, further, when obtaining lithium type polyanion particle | grains (B) shown by said Formula (V), , When obtaining sodium-based polyanion particles (E) of the above formula (VII) or formula (VIII), replace the wording of "lithium" in the step (Y) with "sodium" and, if necessary, "iron" The wording “compound and / or manganese compound” may be replaced with “cobalt compound”.

More specifically, the step (Y) comprises the following (i) to (iii):
(I) mixing a phosphoric acid compound or a silicic acid compound with a mixture (a-1) containing a lithium compound to obtain a complex (a-2),
(Ii) The resulting complex (a-2) and slurry water (a-3) containing at least an iron compound or a metal salt containing a manganese compound are subjected to a hydrothermal reaction to form a complex (a-4) And (iii) calcining the obtained composite (a-4) in a reducing atmosphere or an inert atmosphere.

A process (i) is a process of mixing a phosphoric acid compound with the mixture (a-1) containing a lithium compound, and obtaining a complex (a-2).
Examples of lithium compounds that can be used include lithium hydroxide (eg, LiOH, LiOH · H ₂ O), lithium carbonate, lithium sulfate, and lithium acetate. Among them, lithium hydroxide is preferred.
The content of the lithium compound in the mixture (a-1) is preferably 5 to 50 parts by mass, and more preferably 7 to 45 parts by mass with respect to 100 parts by mass of water. More specifically, the content of the lithium compound in the mixture (a-1) is preferably 5 to 50 parts by mass, and more preferably 10 to 45 parts by mass with respect to 100 parts by mass of water.

  In addition, in order to obtain a lithium-based polyanion particle in which carbon (c1) derived from cellulose nanofibers is supported, cellulose nanofibers containing a lithium compound instead of the above mixture (a-1) in the step (i) A mixture (a-1) ′ containing The content of cellulose nanofibers in the mixture (a-1) ′ is, for example, preferably 0.5 to 15 parts by mass, more preferably 0 based on 100 parts by mass of water in the mixture (a-1) ′. 8 to 10 parts by mass.

  Here, when carbon supported by lithium-based polyanion particles is carbon (c2) derived from a water-soluble carbon material, carbon derived from a cellulose nanofiber (c1) and carbon (c2) derived from a water-soluble carbon material are both To obtain supported lithium-based polyanion particles, replace the word "cellulose nanofiber" in steps (i) to (iii) with "water-soluble carbon material" or "cellulose nanofiber and water-soluble carbon material It should be replaced with ".

  It is preferable to stir the mixture (a-1) in advance before mixing the phosphoric acid compound with the mixture (a-1). The stirring time of the mixture (a-1) is preferably 1 to 15 minutes, more preferably 3 to 10 minutes. Moreover, the temperature of the mixture (a-1) is preferably 20 to 90 ° C., and more preferably 20 to 70 ° C.

Examples of the phosphoric acid compound used in step (i) include orthophosphoric acid (H ₃ PO ₄ , phosphoric acid), metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, triphosphoric acid, tetraphosphoric acid, ammonium phosphate, ammonium hydrogen phosphate and the like. . Among them, it is preferable to use phosphoric acid, and it is preferable to use as a 70 to 90% by mass aqueous solution. In this process (i), when mixing a phosphoric acid with a mixture (a-1), it is preferable to drip a phosphoric acid, stirring a mixture (a-1). By adding phosphoric acid dropwise to the mixture (a-1) little by little, the reaction proceeds well in the mixture (a-1), and the complex (a-2) is uniformly dispersed in the slurry. While being generated, it is possible to effectively suppress the unnecessary aggregation of the complex (a-2).

The dropping rate of phosphoric acid to the above mixture (a-1) is preferably 15 to 50 mL / min, more preferably 20 to 45 mL / min, and still more preferably 28 to 40 mL / min. Moreover, the stirring time of the mixture (a-1) while dropping phosphoric acid is preferably 0.5 to 24 hours, more preferably 3 to 12 hours. Furthermore, the stirring speed of the mixture (a-1) while dropping phosphoric acid is preferably 200 to 700 rpm, more preferably 250 to 600 rpm, and still more preferably 300 to 500 rpm.
In addition, when stirring a mixture (a-1), it is preferable to cool to below the boiling point temperature of a mixture (a-1). Specifically, cooling to 80 ° C. or less is preferable, and cooling to 20 to 60 ° C. is more preferable.

  The mixture (a-1) after mixing the phosphoric acid compound preferably contains 2.7 to 3.3 moles of lithium, and 2.8 to 3.1 moles of lithium per mole of phosphoric acid. Is more preferred.

The reaction in the mixture is completed by purging nitrogen to the mixture (a-1) after mixing the phosphoric acid compound to complete the complex (a-2), which is a precursor of polyanion particles. Form in mixture. When nitrogen is purged, the reaction can be allowed to proceed with the concentration of dissolved oxygen in mixture (a-1) reduced, and the dissolved oxygen in the mixture containing the resulting complex (a-2) Since the concentration is also effectively reduced, the oxidation of iron compounds, manganese compounds and the like added in the next step can be suppressed. In the mixture containing the complex (a-2), the precursor of polyanion particles is present as finely dispersed particles. Such a complex (a-2) is obtained as a complex of trilithium phosphate (Li ₃ PO ₄ ) and cellulose nanofibers.

The pressure at the time of purging nitrogen is preferably 0.1 to 0.2 MPa, more preferably 0.1 to 0.15 MPa. Moreover, the temperature of the mixture (a-1) after mixing a phosphoric acid compound becomes like this. Preferably it is 20-80 degreeC, More preferably, it is 20-60 degreeC. The reaction time is preferably 5 to 60 minutes, more preferably 15 to 45 minutes.
Moreover, when purging nitrogen, it is preferable to stir the mixture (a-1) after mixing a phosphoric acid compound from a viewpoint of making reaction advance favorably. The stirring speed at this time is preferably 200 to 700 rpm, more preferably 250 to 600 rpm.

  Further, from the viewpoint of more effectively suppressing the oxidation of the dispersed particles on the surface of the dispersed particles of the complex (a-2) and achieving the finer dispersed particles, it is dissolved in the mixture (a-1) after the phosphoric acid compound is mixed. The oxygen concentration is preferably 0.5 mg / L or less, more preferably 0.2 mg / L or less.

  In the step (ii), the composite (a-2) obtained in the step (i) and the slurry water (a-3) containing a metal salt containing at least an iron compound or a manganese compound are subjected to a hydrothermal reaction It is a process of obtaining a complex (a-4). The complex (a-2) obtained in the above step (i) is used as a mixture as a precursor of polyanion particles, to which a metal salt containing at least an iron compound or a manganese compound is added to form slurry water ( It is preferable to use as a-3). Thereby, the target polyanion particles become extremely fine particles while simplifying the process. In addition, when the above mixture (a-1) ′ containing cellulose nanofibers is used in the step (i), it becomes possible to efficiently support carbon derived from the cellulose nanofibers on such polyanion particles in the subsequent step, Useful polyanion particles can be obtained.

  Iron compounds which can be used include iron acetate, iron nitrate, iron sulfate and the like. These may be used singly or in combination of two or more. Among these, iron sulfate is preferable from the viewpoint of enhancing the battery characteristics of polyanion particles.

  As a manganese compound which can be used, manganese acetate, manganese nitrate, manganese sulfate etc. are mentioned. These may be used singly or in combination of two or more. Among them, manganese sulfate is preferable from the viewpoint of enhancing the battery characteristics of polyanion particles.

When both an iron compound and a manganese compound are used as the metal salt, the molar ratio (manganese compound: iron compound) of the manganese compound and the iron compound is preferably 99: 1 to 1:99, more preferably 90. 10 to 10:90. Moreover, the total addition amount of these iron compounds and manganese compounds is preferably 0.99 to 1.01 mol, more preferably 1 mol to 1 mol of Li ₃ PO ₄ contained in the slurry water (a-3). Is from 0.995 to 1.005 mol.

Furthermore, if necessary, metal (M ⁶ ) salts other than iron compounds and manganese compounds may be used as metal salts. M ⁶ in the metal salt has the same meaning as M ⁶ in formula (VI), as such a metal salt, can be used sulfates, halides, organic acid salts, and hydrates thereof. These may be used singly or in combination of two or more. Among these, from the viewpoint of enhancing the battery physical properties, it is more preferable to use a sulfate.
When these metal (M ⁶ ) salts are used, the total addition amount of the iron compound, the manganese compound and the metal (M ⁶ ) salt is the phosphoric acid in the complex (a-2) obtained in the above step (i) The amount is preferably 0.99 to 1.01 mol, and more preferably 0.995 to 1.005 mol, per 1 mol.

  The amount of water used in the hydrothermal reaction is the phosphoric acid contained in the slurry water (a-3) from the viewpoint of the solubility of the metal salt used, the ease of stirring, and the efficiency of synthesis, etc. The amount is preferably 10 to 30 mol, more preferably 12.5 to 25 mol, per 1 mol of ions.

In step (ii), the order of addition of the iron compound, the manganese compound and the metal (M ⁶ ) salt is not particularly limited. Moreover, while adding these metal salts, you may add an antioxidant as needed. As such an antioxidant, sodium sulfite (Na ₂ SO ₃ ), sodium hydrosulfite (Na ₂ S ₂ O ₄ ), aqueous ammonia and the like can be used. From the viewpoint of preventing the formation of polyanion particles from being suppressed by the addition of an excess amount of the antioxidant, the total amount of the iron compound, the manganese compound and the metal (M ⁶ ) salt used as needed is 1 Preferably it is 0.01-1 mol with respect to the mole, More preferably, it is 0.03-0.5 mol.

The content of the complex (a-4) in the slurry (a-3) obtained by adding an iron compound, a manganese compound, and a metal (M ⁶ ) salt and an antioxidant which are optionally used is preferably It is 10 to 50% by mass, more preferably 15 to 45% by mass, and still more preferably 20 to 40% by mass.

The hydrothermal reaction in the step (ii) may be 100 ° C. or higher, preferably 130 to 180 ° C. The hydrothermal reaction is preferably carried out in a pressure vessel, and when the reaction is carried out at 130 to 180 ° C., the pressure at this time is preferably 0.3 to 0.9 MPa, and the reaction is carried out at 140 to 160 ° C. Is preferably 0.3 to 0.6 MPa. The hydrothermal reaction time is preferably 0.1 to 48 hours, and more preferably 0.2 to 24 hours.
The obtained complex (a-4) is a complex containing the polyanion particle represented by the above formula (VI), or, when using cellulose nanofibers, contains such polyanion particles and cellulose nanofibers. It is a complex, and after filtration, it can be washed with water and dried to isolate it as complex particles (primary particles) containing cellulose nanofibers. In addition, lyophilization and vacuum drying are used as the drying means.

The BET specific surface area of the resulting composite (a-4) is preferably 5 to 40 m ² / g, more preferably 5 to ²⁰ m ² / g, from the viewpoint of effectively reducing the amount of adsorbed water. When the BET specific surface area of the complex (a-4) is less than 5 m ² / g, the polyanion particles may be too large. When the BET specific surface area exceeds 40 m ² / g, the amount of adsorbed water of the positive electrode active material for a secondary battery may increase to affect the battery characteristics.

  In the next step (iii), the composite (a-4) obtained in the step (ii) is calcined in a reducing atmosphere or an inert atmosphere to obtain a lithium-based polyanion containing carbon (c1) derived from cellulose nanofibers It is a process of obtaining particles (B). When the above-mentioned cellulose nanofibers are used, lithium-based polyanion particles (B) in which carbon (c1) derived from such cellulose nanofibers is firmly supported on the surface by passing through this step (III) You can get it.

  The firing temperature is preferably 500 to 800 ° C., more preferably 600 to 770 ° C., and still more preferably 650 to 750 ° C. from the viewpoint of effectively carbonizing the cellulose nanofibers. The baking time is preferably 10 minutes to 3 hours, more preferably 30 minutes to 1.5 hours.

  In the step (Z), the NCM-based composite oxide secondary particles or NCA-based composite oxide secondary particles (A) or (D) obtained in the step (X), the lithium obtained in the step (Y) In the process of adding the system-based polyanion particles (B) or the sodium-based polyanion particles (E) and, if necessary, the water-insoluble carbon powder (c3), mixing while adding compressive force and shear force to form a complex is there.

  In the step (Z), before the complexing treatment, the layered composite oxide secondary particles (A) or (D) and the lithium-based polyanion particles (B) or the sodium-based polyanion particles (E) are further required. It is preferred to thoroughly dry mix the mixture of water insoluble carbon powder (c3) added accordingly. The dry mixing method is preferably mixing using a common dry mixer such as a ball mill or V blender, and more preferably mixing using a planetary ball mill capable of self-revolution.

  Next, the above-mentioned layered composite oxide secondary particles (A) or (D) and the above lithium-based polyanion particles (B) or sodium-based polyanion particles (E), which are dry-mixed, are further added as required. The mixture of the water-insoluble carbon powder (c3) is a composite effectively formed with the composite oxide particles in only part of the surface of the layered composite oxide secondary particles (A) or (D). From the viewpoint of obtaining, it is preferable to mix while applying compressive force and shear force. The process of mixing while applying compressive force and shear force is preferably performed in a closed vessel equipped with an impeller, a rotor tool, and the like.

For example, when Nobilta (manufactured by Hosokawa Micron Corporation), which is a dry particle composite apparatus equipped with an impeller, is used for the above composite processing, the number of revolutions of the impeller is determined by the layered composite oxide secondary particles (A) or From the viewpoint of obtaining a complex of D) and the above polyanion particles (B) or (E) and further water insoluble carbon powder (c3), it is preferably 2000 to 6000 rpm, more preferably 4000 to 6000 rpm. The mixing time is preferably 1 to 10 minutes, more preferably 5 to 10 minutes.
In addition, when using Erich Intensiv Mixer (manufactured by Nippon Erich Co., Ltd.), which is a high-speed stirring mixer equipped with a rotor tool, for such complexing processing, the number of rotations of such rotor tool is preferably 2000 to 8000 rpm. Preferably it is 4000-8000 rpm. The mixing time is preferably 1 to 10 minutes, more preferably 3 to 10 minutes.

In the step (Z), the processing time and / or the number of revolutions of the impeller etc. when performing the processing of mixing while applying the above-mentioned compressive force and shear force are the layered type composite oxide secondary particles (A) charged into the container Or it is necessary to adjust suitably according to the quantity of the mixture of (D) and polyanion particle | grains (B) or (E), and also water-insoluble carbon powder (c3). Then, by operating the container, while a compressive force and a shear force are applied to the mixture between the impeller or the like and the inner wall of the container, it becomes possible to carry out a process of compounding this, and the above-mentioned layered complex oxide A positive electrode active material for a lithium ion secondary battery or a positive electrode active material for a sodium ion secondary battery in which the polyanion particle and the water insoluble carbon powder (c3) are complexed only in a part of the surface of the secondary particles be able to.
For example, when the complexing process is performed for 1 to 10 minutes in a closed container provided with an impeller rotating at a rotation speed of 2000 to 6000 rpm, the amount of the mixture introduced into the container is an effective container (of the closed containers provided with the impeller The amount is preferably 0.1 to 0.7 g, more preferably 0.15 to 0.4 g, per 1 cm ^{3 of} a container corresponding to a portion capable of containing the above mixture.

Examples of the apparatus equipped with a closed vessel capable of easily performing the compounding process while applying such a compressive force and a shear force include a high-speed shear mill, a blade-type kneader, a high-speed mixer, etc. For example, particle design apparatus COMPOSI, Mechano Hybrid, high-performance fluid mixer FM mixer (manufactured by Nippon Coke Industry Co., Ltd.) fine particle composite apparatus Mechanofusion, Nobilta (manufactured by Hosokawa Micron), surface modification apparatus Miralo, hybridization system (Manufactured by Nara Machine Mfg. Co., Ltd.) and Eirich intensive mixer (manufactured by Nippon Eirich Co., Ltd.) can be suitably used.
As processing conditions for the above-mentioned complexing processing, the processing temperature is preferably 5 to 80 ° C., more preferably 10 to 50 ° C. The treatment atmosphere is not particularly limited, but is preferably in an inert gas atmosphere or a reducing gas atmosphere.

  In addition, only a part of the surface of the layered composite oxide secondary particles (A) or (D) may be added together with the lithium-based polyanion particles (B) or the sodium-based polyanion particles (E) as required. The degree to which the water-insoluble carbon powder (c3) is complexed can be evaluated by X-ray photoelectron spectroscopy (XPS).

  As a secondary battery which is a lithium ion secondary battery or a sodium ion secondary battery to which the positive electrode for secondary batteries containing the positive electrode active material for secondary batteries of the present invention can be applied, the positive electrode, the negative electrode, the electrolyte and the separator are essential There is no particular limitation as long as it has a configuration.

  The positive electrode of a lithium ion secondary battery or a sodium ion secondary battery is prepared by adding N- to a positive electrode active material for a secondary battery of the present invention, a conductive aid such as carbon black, and a binder such as polyvinylidene fluoride. A solvent such as methyl-2-pyrrolidone is added and sufficiently kneaded to obtain a positive electrode slurry, which is then coated on a current collector such as an aluminum foil and then consolidated by a roller press or the like and dried. The positive electrode active material for a secondary battery according to the present invention can effectively suppress the increase in viscosity of the positive electrode slurry obtained by adjustment with the passage of time. Even when applied on top, it can be easily made to have a uniform thickness.

  The negative electrode of the lithium ion secondary battery or sodium ion secondary battery is not particularly limited by its material configuration as long as lithium ions or sodium ions can be stored at the time of charge and released at the time of discharge. Material composition can be used. For example, it is a carbon material such as lithium metal, sodium metal, graphite or amorphous carbon. It is preferable to use an electrode formed of an intercalated material capable of electrochemically absorbing and desorbing lithium ions or sodium ions, particularly a carbon material.

  The electrolytic solution is one in which a supporting salt is dissolved in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent generally used for an electrolyte of a lithium ion secondary battery or a sodium ion secondary battery, and, for example, carbonates, halogenated hydrocarbons, ethers, ketones , Nitriles, lactones, oxolane compounds and the like can be used.

The type of the supporting salt is not particularly limited. In the case of a lithium ion secondary battery, an inorganic salt selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , a derivative of the inorganic salt, LiSO ₃ CF _3, the organic selected from _LiC (SO 3 _{CF 3) 2} and _{LiN (SO 3 CF 3) 2} , LiN (SO 2 C 2 F 5) 2 and _{LiN (SO 2 CF 3) (} SO 2 C 4 F 9) Preferably, it is at least one of a salt and a derivative of the organic salt. In the case of a sodium ion secondary battery, an inorganic salt selected from NaPF ₆ , NaBF ₄ , NaClO ₄ and NaAsF ₆ , a derivative of the inorganic salt, NaSO ₃ CF ₃ , NaC (SO ₃ CF ₃ ) ₂ and NaN (SO) An organic salt selected from ₃ CF ₃ ) ₂ , NaN (SO ₂ C ₂ F ₅ ) ₂ and NaN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), and at least one of derivatives of the organic salt Is preferred.

  The separator serves to electrically insulate the positive electrode and the negative electrode and to hold the electrolytic solution. For example, a porous synthetic resin film, in particular, a porous film of a polyolefin polymer (polyethylene, polypropylene) may be used.

The solid electrolyte electrically insulates the positive electrode and the negative electrode and exhibits high lithium ion conductivity. For example, La _0.51 Li _0.34 TiO _2.94 , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li ₇ La ₃ Zr ₂ O ₁₂ , 50Li ₄ SiO _4. 50Li ₃ BO ₃ , Li _2.9 PO _3.3 N _0.46 , Li _3.6 Si _0.6 P _0.4 O ₄ , Li _1.07 Al _0.69 Ti _1.46 (PO ₄ ) ₃ , Li _{1 .5} Al _0.5 Ge _1.5 (PO ₄ ) ₃ , Li ₁₀ GeP ₂ S ₁₂ , Li _3.25 Ge _0.25 P _0.75 S ₄ , 30 Li ₂ S · 26 B ₂ S ₃ · 44 LiI, 63 Li _{2 S · 36SiS 2 · 1Li 3} PO 4, 57Li 2 S · 38SiS 2 · 5Li 4 SiO 4, 70Li 2 S · 30P 2 S 5, 50Li 2 S · 50GeS 2, Li 7 P 3 S 11, Li _3.25 P _0.95 S ₄ may be used.

  The shape of the lithium ion secondary battery or sodium ion secondary battery having the above configuration is not particularly limited, and various shapes such as coin shape, cylindrical shape, square shape and the like, and indefinite shapes enclosed in a laminate outer package It may be shaped.

  EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[Production Example A: Production of Secondary Particles (Li-NCM-A) of Li-NCM Composite Oxide]
After mixing 263 g of nickel sulfate hexahydrate, 281 g of cobalt sulfate heptahydrate, 241 g of manganese sulfate pentahydrate, and 3 L of water so that the molar ratio of Ni: Co: Mn is 1: 1: 1 To the mixture, 25% ammonia water was dropped at a dropping rate of 300 ml / min to obtain a slurry A1 containing a metal composite hydroxide having a pH of 11.
Next, the slurry A1 was filtered and dried to obtain a mixture B1 of metal composite hydroxides, and then 37 g of lithium carbonate was mixed with the mixture B1 in a ball mill to obtain a powder mixture C1.
The obtained powder mixture C1 is calcined at 800 ° C. for 5 hours in an air atmosphere for disintegration, and then fired as a main calcination at 800 ° C. for 10 hours in an air atmosphere to obtain a Li-NCM composite oxide (LiNi) Secondary particles A of _0.33 Co _0.33 Mn _0.34 O ₂ ) were obtained. (Average particle diameter of secondary particles: 10 μm)
Hereinafter, the Li-NCM composite oxide A is referred to as Li-NCM-A.

Production Example 001: Production of Lithium-Based Polyanion Particles (LMP-A)
A slurry A 001 was obtained by mixing 1272 g of LiOH.H ₂ O and 4 L of water. Next, 1153 g of an 85% aqueous phosphoric acid solution is added dropwise at 35 mL / min while stirring the obtained slurry A 001 for 3 minutes while maintaining the temperature at 25 ° C., followed by cellulose nanofibers (Cerish KY-100G, Daicel Fine Chem (Fiber diameter: 4 to 100 nm) 5892 g was added and stirred at a speed of 400 rpm for 12 hours to obtain a slurry B 001 containing Li ₃ PO ₄ .
Obtained in nitrogen purged slurry B001, added after the dissolved oxygen concentration of the slurry B001 was 0.5 mg / L, the slurry B001 total amount _{to, MnSO 4 · 5H 2 O 1688g} , the FeSO ₄ · 7H 2 O 834g Thus, a slurry C001 was obtained. The molar ratio of added MnSO ₄ to FeSO ₄ (manganese compound: iron compound) was 70:30.
Next, the obtained slurry C001 was put into an autoclave and subjected to a hydrothermal reaction at 170 ° C. for 1 hour. The pressure in the autoclave was 0.8 MPa. After the hydrothermal reaction, the formed crystals were filtered and then washed with 12 parts by mass of water per 1 part by mass of the crystals. The washed crystals were lyophilized at -50 ° C for 12 hours to obtain complex D001.
1000 g of the complex D001 thus obtained was fractionated, and 1 L of water was added thereto to obtain a slurry E001. The obtained slurry E001 is dispersed for 1 minute with an ultrasonic stirrer (T25, manufactured by IKA Co., Ltd.) to make the whole color uniformly, and then a spray dryer (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.) is used. The resultant was subjected to spray drying to obtain a granulated body F001.
The obtained granulated body F001 was calcined at 700 ° C. for 1 hour under an argon-hydrogen atmosphere (hydrogen concentration 3%) to support lithium manganese iron phosphate supporting carbon at 2.0 mass% derived from cellulose nanofibers _{a (LiMn 0.7 Fe 0.3 PO 4} , the amount of carbon = 2.0% by weight, average particle diameter: 100 nm) was obtained.
Hereinafter, the lithium manganese phosphate A is referred to as LMP-A.

Production Example 002: Production of Lithium-Based Polyanion Particles (LMP-B)
The entire amount of the slurry B001 obtained in Production Example 001 was purged with nitrogen to make the dissolved oxygen concentration of the slurry B001 0.5 mg / L, and then 2108 g of CoSO ₄ · 7H ₂ O was added to obtain a slurry C002.
Next, the obtained slurry C002 was put into an autoclave and subjected to a hydrothermal reaction at 170 ° C. for 1 hour. The pressure in the autoclave was 0.8 MPa. After the hydrothermal reaction, the formed crystals were filtered and then washed with 12 parts by mass of water per 1 part by mass of the crystals. The washed crystals were lyophilized at -50 ° C for 12 hours to obtain complex D002.
The obtained complex D002 was calcined at 700 ° C. for 1 hour under an argon-hydrogen atmosphere (hydrogen concentration 3%) to support lithium cobalt phosphate B supporting 2.0 mass% of cellulose nanofiber-derived carbon ( LiCoPO ₄ / C, amount of carbon = 2.0% by mass) was obtained.
Hereinafter, the lithium cobalt phosphate B is referred to as LMP-B.

Production Example 003: Production of Lithium-Based Polyanion Particles (LMP-C)
In the production of lithium-based polyanion particles in Production Example 001, 2.0% by mass of glucose-derived carbon is the same as in Production Example 001, except that the addition of 5892 g of cellulose nanofibers to the slurry A is changed to 125 g of glucose. A supported lithium manganese iron phosphate C (LiMn _0.7 Fe _0.3 PO ₄ , amount of carbon = 2.0 mass%, average particle diameter: 100 nm) was obtained.
Hereinafter, lithium manganese phosphate C is referred to as LMP-C.

Production Example 004: Production of Lithium-Based Polyanion Particles (LMP-D)
In the same manner as in Production Example 001 except that in the production of the lithium-based polyanion particles of Production Example 001, the addition amount 5892 g of cellulose nanofibers to the slurry A 001 is changed to 295 g, 0.1 mass% of cellulose nanofibers derived from carbon There supported manganese phosphate lithium iron _{D (LiMn 0.7 Fe 0.3 PO 4} , the amount = 0.1 weight% of carbon, average particle size: 100 nm) was obtained.
Hereinafter, lithium manganese phosphate B is referred to as LMP-D.

[Example 1: (Li-NCM-A 70% + LMP-A 30%) Complex]
Using 350 g of Li-NCM-A obtained in Production Example A and 150 g of LMP-A obtained in Production Example 001, using Novirta (NOB130, manufactured by Hosokawa Micron), compounding treatment is performed at 2000 rpm for 5 minutes. The positive electrode composite active material for a lithium ion secondary battery in which Li-NCM-A and LMP-A are complexed was obtained.

[Example 2: (Li-NCM-A 70% + LMP-B 30%) Complex]
A positive electrode composite active material for a lithium ion secondary battery was obtained in the same manner as in Example 1 except that LMP-A was changed to LMP-B obtained in Production Example 002.

[Example 3: (Li-NCM-A 70% + LMP-A 30%) Complex]
A positive electrode composite active material for a lithium ion secondary battery was obtained in the same manner as in Example 1 except that the compounding treatment was performed for 5 minutes at 4800 rpm using an Eirich intensive mixer (manufactured by Nippon Eirich Co., EL1).

[Example 4: (Li-NCM-A 70% + LMP-A 30%) Complex]
A positive electrode composite active material for a lithium ion secondary battery was obtained in the same manner as in Example 1 except that the compounding treatment was carried out at 7200 rpm for 3 minutes using an Eirich intensive mixer (manufactured by Nippon Eirich Co., EL1).

[Example 5: (Li-NCM-A 90% + LMP-A 10%) Complex]
Lithium was prepared in the same manner as in Example 1, except that Li-NCM-A was changed to 450 g and LMP-A to 50 g, and the complexing conditions with Nobilta (manufactured by Hosokawa Micron, NOB130) were changed to 4000 rpm for 1 minute. The positive electrode composite active material for an ion secondary battery was obtained.

[Example 6: (Li-NCM-A 70% + LMP-C 30%) Complex]
A positive electrode composite active material for lithium ion secondary battery was obtained in the same manner as in Example 1, except that LMP-A was changed to LMP-C obtained in Production Example 003.

[Example 7: (Li-NCM-A 70% + LMP-D 30%) Complex]
A positive electrode composite active material for a lithium ion secondary battery was obtained in the same manner as in Example 1 except that LMP-A was changed to LMP-D obtained in Production Example 004, and 5 g of graphite was further added.

[Comparative Example 1: (Li-NCM-A 70% + LMP-A 30%) Mixture]
Using a mortar, the mixing process is carried out for 5 minutes using 350 g of Li-NCM-A obtained in Production Example A and 150 g of LMP-A obtained in Production Example 001, and Li-NCM-A and LMP-A Thus, a positive electrode mixture active material for a lithium ion secondary battery, which is simply mixed, is obtained without being complexed.

[Comparative example 2: (Li-NCM-A 70% + LMP-B 30%) mixture]
A positive electrode mixture active material for a lithium ion secondary battery was obtained in the same manner as in Comparative Example 1 except that LMP-A was changed to LMP-B obtained in Production Example 004.

[Comparative example 3: (Li-NCM-A 50% + LMP-A 50%) mixture]
A positive electrode mixture active material for a lithium ion secondary battery was obtained in the same manner as in Comparative Example 1 except that the amount of Li-NCM-A was changed to 250 g and the amount of LMP-A was changed to 250 g.

[Comparative Example 4: (Li-NCM-A 90% + LMP-A 10%) Mixture]
A positive electrode mixture active material for a lithium ion secondary battery was obtained in the same manner as in Comparative Example 1 except that Li-NCM-A was changed to 450 g and LMP-A to 50 g.

[Comparative Example 5: (Li-NCM-A 90% + LMP-A 10%) Complex]
Lithium was prepared in the same manner as Example 1, except that Li-NCM-A was changed to 450 g and LMP-A to 50 g, and the complexation conditions with Nobilta (manufactured by Hosokawa Micron, NOB130) were changed to 2000 rpm for 1 minute. The positive electrode composite active material for an ion secondary battery was obtained.

«Measurement of peak intensity ratio by X-ray photoelectron spectroscopy»
The X-ray photoelectron spectroscopy was measured about the active material of all the Examples and Comparative Example 5, and peak intensity ratio a / b and surface coverage (area%) were calculated | required. Specifically, a micron separator (MS manufactured by Hosokawa Micron) is used to obtain a Li-NCM-based composite oxide particle group from which a lithium-based polyanion particle existing alone is removed without being complexed to the Li-NCM-based composite oxide. The peak intensity a of Ni ₂ p _3/2 derived from Li-NCM-A in the selected X-ray photoelectron spectrum (using device: JPS 9010 MX, manufactured by Nippon Denshi Co., Ltd.), LMP-A, LMP-B, LMP-C or LMP-D The peak intensity ratio a / b divided by the derived (P2p + C1s) peak intensity b was calculated. Moreover, the surface coverage (area%) of the composite oxide secondary particles by the polyanion particles was determined from the above-mentioned formula (1) from the obtained peak intensity ratio a / b.
The results are shown in Table 1.

<< Evaluation of the time-dependent change of viscosity of positive electrode slurry >>
A positive electrode slurry was prepared using the active materials of all the examples and comparative examples described above, and the viscosity of the positive electrode slurry was measured 5 days after immediately after preparation. Specifically, the active materials of the obtained Examples or Comparative Examples, ketjen black, and polyvinylidene fluoride are mixed in a blending ratio of 90: 5: 5 in mass ratio, and N-methyl-2-pyrrolidone is added thereto. The mixture was sufficiently kneaded to prepare a positive electrode slurry. After preparation, the positive electrode slurry is immediately enclosed in a closed vessel, and left for 5 days in a constant temperature environment of 20 ° C., using a B-type viscometer (digital viscometer DV-E manufactured by Brookfield Co., Ltd.). The viscosity at a rotational speed of 100 rpm was determined. The viscosity immediately after preparation of all the positive electrode slurries was around 3500 (mPa · s).
The results are shown in Table 2.

«Transition metal elution amount to electrolyte solution»
The positive electrode slurry immediately after preparation obtained by the evaluation of the change with time of the viscosity of the positive electrode slurry is applied to a current collector made of an aluminum foil with a thickness of 20 μm using a coating machine, and vacuum drying is performed at 80 ° C. for 12 hours. The Then, it punched out in disk shape of (phi) 14 mm, and pressed for 2 minutes at 16 MPa using a hand press, and it was set as the positive electrode.
Subsequently, a coin-type secondary battery was constructed using the above positive electrode. As a negative electrode, a lithium foil (in the case of a lithium ion secondary battery) punched out to φ 15 mm was used. The electrolytic solution volume of ethylene carbonate and ethyl methyl carbonate ratio of 3: 7 mixed solvent in a mixing ratio of, with a LiPF ₆ that was dissolved at a concentration of 1 mol / L. For the separator, a known one such as a polymeric porous film such as polypropylene was used. These battery parts were incorporated and stored in an atmosphere having a dew point of −50 ° C. or less by a conventional method to obtain a coin-type secondary battery (CR-2032).

The obtained secondary battery was charged. Specifically, constant current charging at a current of 170 mA / g and a voltage of 4.5 V was performed.
Thereafter, the secondary battery was disassembled, and the taken-out positive electrode was washed with dimethyl carbonate and then immersed in an electrolytic solution. The electrolyte used at this time was prepared by dissolving LiPF ₆ at a concentration of 1 mol / L in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a ratio of 1: 1 in volume ratio. The electrolytic solution in which the positive electrode was immersed was placed in a closed vessel and allowed to stand at 70 ° C. for one week.
After standing, the electrolytic solution from which the positive electrode was taken out was filtered with a 0.45 μm dissic filter and acid-decomposed with nitric acid. Mn, Co, and Ni derived from the Li-NCM composite oxide contained in the acid-decomposed electrolytic solution were quantified using ICP emission spectroscopy (using device: ULTIMA2 manufactured by Horiba, Ltd.).
The results are shown in Table 2.

«Evaluation of discharge characteristics»
0.2 C (34 mAh) at a temperature of 30 ° C. with a discharge capacity measuring device (HJ-1001 SD8, manufactured by Hokuto Denko Co., Ltd.) using the secondary battery manufactured by the above evaluation of the transition metal elution amount to the electrolytic solution The initial discharge capacities of / g) and 3C (510 mAh / g) were measured.
The results are shown in Table 2.

As apparent from Table 2, the positive electrode slurry using the active material obtained in the example as a positive electrode active material has a viscosity that is longer than that of the positive electrode slurry using the active material obtained in the comparative example as a positive electrode active material It can be seen that the change is small and the workability is excellent.
Moreover, compared with the lithium ion secondary battery using the active material obtained by the comparative example as a positive electrode active material, the transition metal component of the lithium ion secondary battery using the active material obtained in the Example as a positive electrode active material It can be seen that it has a good discharge capacity while suppressing elution to the electrolyte solution effectively to ensure the same or higher safety.

Claims (14)

The following formula ( II):
LiNi _d Co _e Al _f M ² _y O ₂ (II)
(Wherein M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and D represents one or more elements selected from Ge, d, e, f and y each satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ It shows a number satisfying y ≦ 0.3 and 3d + 3e + 3f + (valence of M ² ) × y = 3)
In part of the surface of the layered lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (V):
LiCo _g M ⁵ _i PO ₄ (V)
(In the formula (V), M ⁵ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G and i satisfy 0 <g ≦ 1 , 0 ≦ i ≦ 0.3, and 2 g + (number of valences of M ⁵ ) × i = 2.
Or, the following formula (VI):
LiFe _m Mn _n M ⁶ _o PO ₄ (VI)
(In the formula (VI), M ⁶ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ⁶ ) × o = 2 is satisfied.)
And lithium complex polyanion particles (B) formed by supporting carbon (c) on the surface, and lithium complex oxide particles are complexed,
The mass ratio ((A) :( B)) of the content of the layered lithium composite oxide secondary particles (A) to the content of the lithium-based polyanion particles (B) is 90:10 to 60:40. ,
The average particle diameter of the lithium-based polyanion particles (B) is 20 to 200 nm, and the peak intensity ratio according to X-ray photoelectron spectroscopy (XPS) ((peak intensity of Ni2p _3/2 ) / (peak intensity of P2p + peak of C1s) Positive electrode active material for lithium ion secondary batteries in which the strength)) exceeds 0.05 and is 0.31 or less.   The lithium according to claim 1, wherein the amount of carbon (c) supported on the surface of the lithium-based polyanion particles (B) is 0.1% by mass or more and less than 5% by mass in 100% by mass of the lithium-based polyanion particles (B). Positive electrode active material for ion secondary batteries. The carbon (c) supported on the surface of the lithium-based polyanion particles (B) is carbon derived from cellulose nanofibers (c1) or carbon derived from a water-soluble carbon material (c2) according to claim 1 or 2 . Positive electrode active material for lithium ion secondary batteries. Water-insoluble carbon powder (c3) other than cellulose nanofiber-derived carbon (c1) is combined with lithium-based polyanion particles (B) only on a part of the surface of layered lithium composite oxide secondary particles (A) Become
The content of the water-insoluble carbon powder (c3) is a total of 100 parts by mass of lithium composite oxide secondary particles (A) and lithium-based polyanion particles (B) having carbon (c) supported on the surface. The positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 3 , containing 0.5 to 10 parts by mass. A step of mixing and compounding layered lithium secondary oxide secondary particles (A) and lithium-based polyanion particles (B) having carbon (c) supported on the surface while applying compressive force and shear force A method for producing a positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 3 , comprising: Layered lithium composite oxide secondary particles (A), lithium-based polyanion particles (B) having carbon (c) supported on the surface, and water-insoluble carbon powder (c3) other than cellulose nanofiber-derived carbon (c1) The method for producing a positive electrode active material for a lithium ion secondary battery according to claim 4 , comprising the step of mixing and compounding while adding compressive force and shear force. The following formula (III):
NaNi _{a '} Co _b' Mn _{c '} M ³ _x' O ₂ (III)
(Wherein M ³ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, A ', b', c 'and x' each represents 0.3 ≦ a ′ <1, 0 <b ′ ≦ 0.7, 0 <a c ′ ≦ 0.7, 0 ≦ x ′ ≦ 0.3, and 3a ′ + 3b ′ + 3c ′ + (valence number of M ³ ) × x ′ = 3.
Or, the following formula (IV):
NaNi _d' Co _{e '} Al _f' M ⁴ _{y '} O ₂ (IV)
(Wherein, in the formula (IV), M ⁴ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and And d ′, e ′, f ′ and y ′ each represent 0.4 ≦ d ′ <1, 0 <e ′ ≦ 0.6, 0 <f ′.数 0.3, 0 y y '0.3 0.3, and 3d' + 3e '+ 3f' + (valence number of M ⁴ ) x y '= 3 is satisfied.)
In part of the surface of the layered sodium complex oxide secondary particles (D) consisting of sodium complex oxide particles represented by the following formula (VII):
NaCo _{g '} M ⁷ _i' PO ₄ ... (VII)
(In the formula (VII), M ⁷ represents Fe, Mn, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G ′ and i ′ satisfy 0 <g '0 1, 0 i i' 2 0.3, and 2g '+ (valence number of M ⁷ ) = 2i' = 2 is satisfied),
Or the following formula (VIII):
NaFe _{m '} Mn _n' M ⁸ _{o '} PO ₄ ... (VIII)
(In the formula (VIII), M ⁸ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M ′, n ′, and o ′ are 0 ≦ m ′ ≦ 1, 0 ≦ n ′ ≦ 1, 0 ≦ o ′ ≦ 0.3, and m ′ + n ′ ≠ 0, and 2m ′ + 2n ′ + (valence of M ⁸ ) × o ′ = 2 Indicates the number that satisfies
And sodium-based polyanion particles (E) on the surface of which carbon (c) is supported, and sodium complex oxide particles.
Peak intensity ratio ((peak intensity of Ni2p _3/2 ) / (peak intensity of P2p + peak intensity of C1s) by X-ray photoelectron spectroscopy (XPS) is more than 0.05 and less than 0.4 Positive electrode active material for battery. The sodium according to claim 7 , wherein the amount of carbon (c) supported on the surface of the sodium-based polyanion particles (E) is 0.1% by mass or more and less than 5% by mass in 100% by mass of the sodium-based polyanion particles (E). Positive electrode active material for ion secondary batteries. The mass ratio ((D) :( E)) of the content of the layered sodium complex oxide secondary particles (D) to the content of the sodium-based polyanion particles (E) is 95: 5 to 50:50. The positive electrode active material for a sodium ion secondary battery according to claim 7 or 8 . The average particle size of the sodium-based polyanion particles (E) is positive electrode active material for a sodium ion secondary battery according to any one of claims 7-9 is 50 to 200 nm. Sodium-based polyanion particles carbons obtained by carried on the surface of the (E) (c) is any one of claims 7 to 10 carbon derived from cellulose nanofibers (c1) or water-soluble carbon material from a carbon (c2) The positive electrode active material for sodium ion secondary batteries as described in 1 item. Water-insoluble carbon powder (c3) other than cellulose nanofiber-derived carbon (c1) is complexed with only sodium polyanion particles (E) only on part of the surface of layered lithium composite oxide secondary particles (D) Become
The content of the water-insoluble carbon powder (c3) is a total of 100 parts by mass of sodium composite oxide secondary particles (D) and sodium-based polyanion particles (E) formed by supporting carbon (c) on the surface. The positive electrode active material for a sodium ion secondary battery according to any one of claims 7 to 11 , wherein the amount is 0.5 to 24 parts by mass. Process of mixing and compounding layered sodium complex oxide secondary particles (D) and sodium-based polyanion particles (E) having carbon (c) supported on the surface while applying compressive force and shear force method for producing a sodium ion secondary battery positive electrode active material body according to any one of claims 7 to 11, comprising a. Layered sodium composite oxide secondary particles (D), sodium-based polyanion particles (E) having carbon (c) supported on the surface, and water-insoluble carbon powder (c3) other than cellulose nanofibers derived from carbon (c1) The method for producing a positive electrode active material for a sodium ion secondary battery according to claim 12 , comprising the step of mixing and compounding while adding compressive force and shear force.