JP2021051832A - Mixed type positive electrode active material for lithium ion secondary battery, and method for manufacturing positive electrode for lithium ion secondary battery - Google Patents

Abstract

To provide a positive electrode active material for a lithium ion secondary battery for obtaining a lithium ion secondary battery which can effectively increase an electrode density while ensuring a superior discharge capacity and an excellent long-term cycle characteristic.SOLUTION: A mixed type positive electrode active material for a lithium ion secondary battery comprises: a positive electrode active material composite (C) for a lithium ion secondary battery, which is arranged by compositing, only on surfaces of lithium composite oxide secondary particles (A) formed by lithium composite oxide particles (a) represented by a particular formula, lithium-based polyanion particles (B) represented by a particular formula and including carbon (c) supported thereon, and lithium composite oxide particles (a); and lithium-based polyanion particles (B') represented by the particular formula, which are blended in a mass proportion of ((B'):(C))=91:9 to 50:50. In a mixed type positive electrode active material for a lithium ion secondary battery, a ratio (RC/RB') an average particle diameter (RC) the positive electrode active material composite (C) for a lithium ion secondary battery to an average particle diameter (RB') of the lithium-based polyanion particles (B') is 0.2 to 0.98.SELECTED DRAWING: None

Description

The present invention is a mixed positive electrode active material for a lithium ion secondary battery and a lithium ion secondary that can secure excellent cycle characteristics and discharge capacity by obtaining a positive electrode with an effectively increased electrode density in a lithium ion secondary battery. The present invention relates to a method for manufacturing a positive electrode for a battery.

Lithium composite oxides such as lithium nickel manganese cobalt composite oxide and lithium nickel aluminum cobalt composite oxide are widely used in high output and high capacity lithium ion secondary batteries. Such a lithium composite oxide exhibits a layered structure in which a lithium atomic layer and a transition metal atomic layer are alternately stacked via an oxygen atomic layer, and one lithium atom is contained in each atom of the transition metal, so-called. It has a layered rock salt type structure.

In a lithium ion secondary battery using such a lithium composite oxide as a positive electrode, charging / discharging is performed by desorbing / inserting lithium ions into the lithium composite oxide, but usually, the capacity increases as the charge / discharge cycle is repeated. There is a risk that the battery capacity will drop significantly, especially if it is used for a long period of time. It is considered that this is because the transition metal component of the lithium composite oxide elutes into the electrolytic solution during charging, so that the crystal structure is likely to collapse. Further, when the crystal structure of the lithium composite oxide is disintegrated, the transition metal component of the lithium composite oxide is eluted into the surrounding electrolytic solution, which may reduce the thermal stability and impair the safety.
Therefore, conventionally, various developments have been made in order to impart various performances required for lithium ion secondary batteries.

For example, Patent Document 1 discloses a composite powder for an electrode in which electrode active materials such as lithium manganese phosphate are bonded to each other via a conductive material and have a specific bonding strength, and the obtained lithium ion battery is obtained. In, we are trying to impart excellent charge / discharge cycle characteristics that show high current density and high energy density. Further, Patent Document 2 specifies composite particles in which particles of a lithium nickel composite oxide are coated with carbon-coated particles of a lithium phosphate compound having an olivine structure and particles in which a lithium phosphate compound having an olivine structure is carbon-coated. The positive electrode contained in the positive electrode active material layer in an amount is disclosed, and the thermal stability of the obtained lithium ion battery is improved.

Japanese Unexamined Patent Publication No. 2005-135723 Japanese Unexamined Patent Publication No. 2019-91638

However, even if the powder described in Patent Document 1 is used, there is room for improvement in the discharge capacity of the obtained secondary battery. Further, even with the positive electrode described in Patent Document 2, further improvement is required in order to secure excellent cycle characteristics and discharge capacity when the obtained secondary battery is used for a long period of time.

Therefore, the subject of the present invention is a positive electrode active material for a lithium ion secondary battery for obtaining a lithium ion secondary battery capable of ensuring excellent cycle characteristics and discharge capacity by obtaining a positive electrode having an effectively increased electrode density. Is to provide.

Therefore, as a result of diligent studies to solve the above problems, the present inventor has made a composite of specific lithium-based polyanion particles only on the surface of specific lithium composite oxide secondary particles for a lithium ion secondary battery. A mixed positive electrode active material for a lithium ion secondary battery, which is formed by blending lithium-based polyanionic particles having a specific size with a positive electrode active material composite in a specific mass ratio, has a layered rock salt type structure. It effectively suppresses the reaction between the lithium composite oxide and the electrolytic solution, has a high discharge capacity, satisfactorily suppresses a decrease in output even after long-term use, and effectively develops a high electrode density. We have found that it is possible to construct a lithium-ion secondary battery that can be used.

Therefore, the present invention has the following formula (I):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, 0 ≦. A number satisfying w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3 is shown.)
Alternatively, the following formula (II):
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (II)
(In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, x are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ A number satisfying x ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × x = 3 is shown.)
Only on the surface of the lithium composite oxide secondary particles (A) composed of the lithium composite oxide particles (a) represented by the following formula (III) or formula (IV):
Li _g Mn _h Fe _i M ³ _y PO ₄・ ・ ・ (III)
(In formula (III), M ³ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G, h, i, and y are Satisfy 0 <g ≦ 1.2, 0 ≦ h ≦ 1.2, 0 ≦ i ≦ 1.2, 0 ≦ y ≦ 0.3, and h + i ≠ 0, and g + (valence of Mn) × h + ( Fe valence) x i + (M ³ valence) x y = 3 is shown.)
^{_{Li j Fe k Mn l M 4}} z SiO 4 ··· (IV)
(In formula (IV), M ⁴ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. l and z satisfy 0 <j ≦ 2.4, 0 ≦ k ≦ 1.2, 0 ≦ l ≦ 1.2, 0 ≦ z ≦ 1.2, and k + l ≠ 0, and j + (of Fe). Valuation) × k + (Mn valence) × l + (M ⁴ valence) × z = 4).
A positive electrode active material composite for a lithium ion secondary battery in which lithium-based polyanion particles (B) containing carbon (c) represented by and supported by carbon (c) and lithium composite oxide particles (a) are composited (a positive electrode active material composite for a lithium ion secondary battery). Against C)
Further, the mass ratio ((B') :( C)) = 91 of the lithium-based polyanion particles (B') represented by the above formula (III) or the formula (IV) and containing the carbon (c) supported. : 9 to 50: average particle diameter of it was blended with 50, and an average particle diameter of the lithium-ion secondary battery positive electrode active material composite _(C) (R C) and lithium polyanion particles (B ') (R _B' ) provides a mixed positive electrode active material for a lithium ion secondary battery having a ratio ( _RC / R _{B') of 0.2 to 0.98.}

Further, the present invention has the following formula (I):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, 0 ≦. A number satisfying w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3 is shown.)
Alternatively, the following formula (II):
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (II)
(In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, x are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ A number satisfying x ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × x = 3 is shown.)
Only on the surface of the lithium composite oxide secondary particles (A) composed of the lithium composite oxide particles (a) represented by the following formula (III) or formula (IV):
Li _g Mn _h Fe _i M ³ _y PO ₄・ ・ ・ (III)
(In formula (III), M ³ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G, h, i, and y are Satisfy 0 <g ≦ 1.2, 0 ≦ h ≦ 1.2, 0 ≦ i ≦ 1.2, 0 ≦ y ≦ 0.3, and h + i ≠ 0, and g + (valence of Mn) × h + ( Fe valence) x i + (M ³ valence) x y = 3 is shown.)
^{_{Li j Fe k Mn l M 4}} z SiO 4 ··· (IV)
(In formula (IV), M ⁴ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. l and z satisfy 0 <j ≦ 2.4, 0 ≦ k ≦ 1.2, 0 ≦ l ≦ 1.2, 0 ≦ z ≦ 1.2, and k + l ≠ 0, and j + (of Fe). Valuation) × k + (Mn valence) × l + (M ⁴ valence) × z = 4).
A positive electrode active material composite for a lithium ion secondary battery in which lithium-based polyanion particles (B) containing carbon (c) represented by and supported by carbon (c) and lithium composite oxide particles (a) are composited (a positive electrode active material composite for a lithium ion secondary battery). Against C)
Further, the mass ratio ((B') :( C)) = 91 of the lithium-based polyanionic particles (B') represented by the above formula (III) or the formula (IV) and containing the carbon (c) supported. A method for producing a positive electrode for a lithium ion secondary battery, comprising a step of blending at a ratio of 9 to 50:50, blending a conductive auxiliary agent and a binder, and preparing a positive electrode paste.
The positive electrode active material composite for a lithium ion secondary battery average particle diameter of _(C) (R C) and 'average particle diameter of the (R B lithium polyanion particles _(B)') ratio of (R _C / R B _' ) Is 0.2 to 0.98, the present invention provides a method for producing a positive electrode for a lithium ion secondary battery.

According to the mixed positive electrode active material for a lithium ion secondary battery of the present invention, the reaction between the lithium composite oxide and the electrolytic solution is effectively suppressed, and excellent long-term cycle characteristics are maintained while maintaining a high discharge capacity. It is possible to realize a lithium ion secondary battery that can be effectively expressed.

Hereinafter, the present invention will be described in detail.
The mixed positive electrode active material (D) for a lithium ion secondary battery of the present invention has the following formula (I):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, 0 ≦. A number satisfying w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3 is shown.)
Alternatively, the following formula (II):
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (II)
(In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, x are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ A number satisfying x ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × x = 3 is shown.)
Only on the surface of the lithium composite oxide secondary particles (A) composed of the lithium composite oxide particles (a) represented by the following formula (III) or formula (IV):
Li _g Mn _h Fe _i M ³ _y PO ₄・ ・ ・ (III)
(In formula (III), M ³ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G, h, i, and y are Satisfy 0 <g ≦ 1.2, 0 ≦ h ≦ 1.2, 0 ≦ i ≦ 1.2, 0 ≦ y ≦ 0.3, and h + i ≠ 0, and g + (valence of Mn) × h + ( Fe valence) x i + (M ³ valence) x y = 3 is shown.)
^{_{Li j Fe k Mn l M 4}} z SiO 4 ··· (IV)
(In formula (IV), M ⁴ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. l and z satisfy 0 <j ≦ 2.4, 0 ≦ k ≦ 1.2, 0 ≦ l ≦ 1.2, 0 ≦ z ≦ 1.2, and k + l ≠ 0, and j + (of Fe). Valuation) × k + (Mn valence) × l + (M ⁴ valence) × z = 4).
A positive electrode active material composite for a lithium ion secondary battery in which lithium-based polyanion particles (B) containing carbon (c) represented by and supported by carbon (c) and lithium composite oxide particles (a) are composited (a positive electrode active material composite for a lithium ion secondary battery). Against C)
Further, the mass ratio ((B') :( C)) = 91 of the lithium-based polyanionic particles (B') represented by the above formula (III) or the formula (IV) and containing the carbon (c) supported. A mixed positive electrode active material for lithium ion secondary batteries, which is blended at a ratio of 9 to 50:50.
The positive electrode active material composite for a lithium ion secondary battery average particle diameter of _(C) (R C) and 'average particle diameter of the (R B lithium polyanion particles _(B)') ratio of (R _C / R B _' ) Is 0.2 to 0.98.

That is, in the present invention, lithium formed by combining the specific lithium-based polyanion particles (B) and the lithium composite oxide particles (a) only on the surface of the specific lithium composite oxide secondary particles (A). The specific lithium-based polyanion particles (B') are blended with the positive electrode active material composite (C) for an ion secondary battery at a mass ratio ((B') :( C)) = 91: 9 to 50:50. The mixed positive electrode active material (D) for a lithium ion secondary battery, which mainly contains lithium-based polyanionic particles as a whole, and has an average particle size of the positive electrode active material composite (C) for a lithium ion secondary battery. and 'average particle diameter of the (R B (R _C) and lithium polyanion particles _(B)'), but the positive electrode active material mixture-type lithium-ion secondary battery has an ultimate was ratios comprising from 0.2 to 0.98 (D).

The lithium nickel composite oxide represented by the above formula (I) (so-called Li-Ni-Co-Mn oxide, hereinafter referred to as "NCM-based composite oxide") particles, and the above formula (II). The lithium nickel composite oxide represented by (the so-called Li-Ni-Co-Al oxide, hereinafter referred to as "NCA-based composite oxide") particles are all particles having a layered rock salt type structure.

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

In the NCM-based composite oxide represented by the above formula (I), Ni, Co and Mn are known to have excellent electron conductivity and 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 replaced by another metal element M 1.} By substituting with these metal elements M ¹ , the crystal structure of the NCM-based composite oxide represented by the formula (I) is stabilized, so that the collapse of the crystal structure can be suppressed even if charging and discharging are repeated for a long period of time. , It is considered that excellent cycle characteristics can be realized.
Specific examples of the NCM-based 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 , and the like. Examples thereof include _{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. Among them, a composition having a large amount of Ni such as _{LiNi 0.8} Co _0.1 Mn _0.1 O ₂ and LiNi _0.6 Co _0.2 Mn _0.2 O ₂ is preferable when the discharge capacity is important _{, and LiNi 0.33 when the cycle characteristics are important.} A composition with a small amount of Ni, such as _{Co 0.33} Mn _0.34 O ₂ , LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O _{2, is preferable.}

Further, two or more kinds of NCM-based composite oxide particles represented by the above formula (I), which are different from each other, have a core-shell structure lithium composite oxide having a core portion (inside) and a shell portion (surface layer portion). Secondary particles (A) (NCM-based composite oxide secondary particles (A)) may be formed.
By forming the NCM-based composite oxide secondary particles (A) forming this core-shell structure, it is easy to elute into the electrolytic solution and release oxygen which adversely affects safety, or in a solid electrolyte. NCM-based composite oxide particles having a high Ni concentration that easily reacts with the solid electrolyte can be arranged in the core portion, and NCM-based composite oxide particles having a low Ni concentration can be arranged in the shell portion in contact with the electrolytic solution. It is possible to further improve the suppression of deterioration of cycle characteristics and the assurance of safety over a period of time. At this time, the core portion may have one phase or may be composed of two or more phases having different compositions. As an embodiment in which the core portion is composed of two or more phases, a structure in which a plurality of phases are concentrically stacked in layers may be used, or a structure in which the composition changes transitionally from the surface of the core portion to the central portion. Good.
Further, the shell portion may be formed on the outside of the core portion, and may be one phase like the core portion, or may be composed of two or more phases having different compositions.

As the NCM-based composite oxide secondary particles (A) formed by forming a core-shell structure with two or more types of NCM-based composite oxide particles having different compositions, specifically, (core portion)-(shell). Part), for example, (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ )-(LiNi _0.2 Co _0.4 Mn _0.4 O ₂ ), (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ )-(LiNi _1/3 Co _1/3 Mn _{1 / Particles composed of 3} O ₂ ) or (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ )-(LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O ₂ ) and the like can be mentioned.

Further, the NCM-based composite oxide particles represented by the above formula (I) may be coated with a metal oxide, a metal fluoride or a metal phosphate. By coating the NCM-based composite oxide particles with these metal oxides, metal fluorides or metal phosphates, the metal component (Ni, Mn, Co or M ¹ ) from the NCM-based composite oxide particles into the electrolytic solution. Elution can be suppressed. Such coatings include CeO ₂ , SiO ₂ , MgO, Al ₂ O ₃ , ZrO ₂ , TiO ₂ , ZnO, RuO ₂ , SnO ₂ , CoO, Nb ₂ O ₅ , CuO, V ₂ O ₅ , MoO ₃ , and so on. _{la 2 O 3, WO 3,} AlF 3, NiF 2, MgF 2, Li 3 PO 4, Li 4 P 2 O 7, LiPO 3, Li 2 PO 3 F, and one selected from LiPO ₂ F ₂ or Two or more kinds or a composite product of these can be used.

The average particle size of the primary particles (a) of the NCM-based composite oxide represented by the above formula (I) is preferably 500 nm or less, more preferably 300 nm or less. By setting the average particle size of the primary particles (a) of the NCM-based composite oxide to at least 500 nm or less in this way, the amount of expansion and contraction of the primary particles due to the insertion and desorption of lithium ions can be suppressed. , Particle cracking can be effectively prevented. The lower limit of the average particle size of the primary particles (a) is not particularly limited, but is preferably 50 nm or more from the viewpoint of handling.

The average particle size of NCM-based mixed oxide secondary particle in which the primary particles are formed by aggregation _(A) (R A) is preferably 1Myuemu～15myuemu, more preferably 4Myuemu～13myuemu. When the average particle size ( _RA ) of the secondary particles is within the above range, a battery having excellent long-term cycle characteristics can be obtained more reliably.
Here, the average particle size in the present specification means the average value of the measured values of the particle size (length of the major axis) of several tens of particles in the observation using an electron microscope of SEM or TEM.

In the present specification, the NCM-based composite oxide secondary particles (A) include only the primary particles (a) formed of the secondary particles, such as lithium-based polyanionic particles (B) and carbon (c). Contains no other ingredients.

When the NCM-based composite oxide particles represented by the above formula (I) form a core-shell structure in the NCM-based composite oxide secondary particles (A), the average as the primary particles forming the core portion. The particle size is preferably 50 nm to 500 nm, more preferably 50 nm to 300 nm. The average particle size of the core portion formed by the aggregation of the primary particles is preferably 1 μm to 15 μm, and more preferably 4 μm to 13 μm.
The average particle size of the NCM-based composite oxide particles constituting the shell portion covering the surface of the core portion as primary particles is preferably 50 nm to 500 nm, more preferably 50 nm to 300 nm. The layer thickness of the shell portion formed by agglomeration of the primary particles is preferably 0.1 μm to 5 μm, and more preferably 0.1 μm to 2.5 μm.

The internal void ratio of the secondary particles (A) composed of the NCM-based composite oxide represented by the above formula (I) is such that the expansion of the NCM-based composite oxide due to the insertion of lithium ions occurs in the internal voids of the secondary particles. From the viewpoint of allowing it, 4% by volume to 12% by volume is preferable, and 5% by volume to 10% by volume is more preferable, out of 100% by volume of the secondary particles of the NCM-based composite oxide.

Next, the NCA-based composite oxide represented by the formula (II) will be described.
^{M 2} in the above formula (II) is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi. And one or more elements selected from Ge.
Further, d, e, f, x in the above formula (II) are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ x ≦ 0.3, And it is a number satisfying 3d + 3e + 3f + ( ^{valence of M 2} ) × x = 3.

The NCA-based composite oxide represented by the above formula (II) is further superior in battery capacity and output characteristics to the NCM-based composite oxide represented by the formula (I). In addition, due to the inclusion of Al, deterioration due to moisture in the atmosphere is unlikely to occur, and it is also excellent in safety.
Specific examples of the NCA-based 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 _0.05 O ₂ , and so on. Examples thereof include _{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. Of these, LiNi _0.8 Co _0.15 Al _0.05 O ₂ and LiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ are preferable.

Further, the NCA-based composite oxide particles represented by the above formula (II) may be coated with a metal oxide, a metal fluoride or a metal phosphate. By coating the NCA-based composite oxide particles with these metal oxides, metal fluorides or metal phosphates, the metal component (Ni, Al, Co or M ² ) from the NCA-based composite oxide particles into the electrolytic solution. Elution can be suppressed. Such coatings include CeO ₂ , SiO ₂ , MgO, Al ₂ O ₃ , ZrO ₂ , TiO ₂ , ZnO, RuO ₂ , SnO ₂ , CoO, Nb ₂ O ₅ , CuO, V ₂ O ₅ , MoO ₃ , and so on. _{la 2 O 3, WO 3,} AlF 3, NiF 2, MgF 2, Li 3 PO 4, Li 4 P 2 O 7, LiPO 3, Li 2 PO 3 F, and one selected from LiPO ₂ F ₂ or Two or more kinds or a composite product of these can be used.

The average particle size of the Formula average particle diameter of primary particles of NCA based composite oxide represented by (II), NCA based mixed oxide secondary particle in which the primary particles are formed by aggregation _(A) (R A ) And the internal void ratio of the secondary particles are the same as those of the above NCM-based composite oxide.
That is, the average particle size of the primary particles (a) of the NCA-based composite oxide represented by the above formula (II) is preferably 500 nm or less, more preferably 300 nm or less, from the above primary particles (a). The average particle size (RA) of the NCA-based composite oxide secondary particles ( _A ) is preferably 1 μm to 15 μm, and more preferably 4 μm to 13 μm. Further, the internal porosity of the NCA-based composite oxide secondary particles (A) composed of the NCA-based composite oxide represented by the above formula (II) is 4% by volume to 12 in 100% of the volume of the secondary particles. It is preferably by volume, more preferably 5% to 10% by volume.

The lithium composite oxide secondary particles (A) of the present invention may contain a mixture of the NCM-based composite oxide represented by the above formula (I) and the NCA-based composite oxide represented by the above formula (II). Good. In the mixed state, the primary particles (a) of the NCM-based composite oxide represented by the above formula (I) and the primary particles (a) of the NCA-based composite oxide represented by the above formula (II) coexist. Secondary particles (A) composed of only the NCM-based composite oxide (a) represented by the above formula (I) and the NCA system represented by the above formula (II) may be formed. Secondary particles (A) composed of only the composite oxide (a) may be mixed, and further, the primary particles (a) of the NCM-based composite oxide represented by the above formula (I) and the above formula (II). ), A secondary particle (A) in which the primary particles (a) of the NCA-based composite oxide coexist, and a secondary particle (A) consisting of only the NCM-based composite oxide (a) represented by the above formula (I). Secondary particles (A) composed of only particles (A) and NCA-based composite oxide (a) represented by the above formula (II) may be mixed. Further, in the case of the secondary particles (A) composed of only the NCM-based composite oxide particles (a) represented by the above formula (I), two or more types of NCM-based composite oxide particles (a) having different compositions from each other. It may be formed by forming a core-shell structure.

The ratio (mass) of the NCM-based composite oxide and the NCA-based composite oxide when the NCM-based composite oxide represented by the above formula (I) and the NCA-based composite oxide represented by the above formula (II) are mixed. %) May be appropriately adjusted according to the desired battery characteristics.

On the surface of the secondary particles (A) composed of the NCM-based composite oxide represented by the above formula (I) and / or the NCA-based composite oxide represented by the above formula (II), the NCM-based composite oxide particles and Since the lithium-based polyanion particles (B) or the NCA-based composite oxide particles and the lithium-based polyanion particles (B) are composited so as to cover the surface of the secondary particles, the NCM-based composite oxide is formed. Elution of metal elements contained in particles or NCA-based composite oxide particles can be suppressed.

Next, the lithium-based polyanion particles (B) will be described.
The lithium-based polyanion particles (B), which are composited with the lithium composite oxide particles (a) only on the surface of the lithium composite oxide secondary particles (A), contain the supporting carbon (c). And the following formula (III):
Li _g Mn _h Fe _i M ³ _y PO ₄・ ・ ・ (III)
(In formula (III), M ³ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G, h, i, and y are Satisfy 0 <g ≦ 1.2, 0 ≦ h ≦ 1.2, 0 ≦ i ≦ 1.2, 0 ≦ y ≦ 0.3, and h + i ≠ 0, and g + (valence of Mn) × h + ( Fe valence) x i + (M ³ valence) x y = 3 is shown.)
Alternatively, the following formula (IV):
^{_{Li j Fe k Mn l M 4}} z SiO 4 ··· (IV)
(In formula (IV), M ⁴ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. l and z satisfy 0 <j ≦ 2.4, 0 ≦ k ≦ 1.2, 0 ≦ l ≦ 1.2, 0 ≦ z ≦ 1.2, and k + l ≠ 0, and j + (of Fe). Valuation) × k + (Mn valence) × l + (M ⁴ valence) × z = 4).
A lithium compound containing at least either manganese or iron, represented by, which can provide good lithium ion conductivity.

The lithium-based polyanionic particles (B) represented by the above formula (III) include the positive electrode active material composite (C) for a lithium ion secondary battery obtained by combining with the lithium composite oxide secondary particles (A). From the viewpoint of the average discharge voltage, 0.5 ≦ h ≦ 1.2 is preferable, 0.6 ≦ h ≦ 1.1 is more preferable, 0.65 ≦ h ≦ 1.05 is further preferable, and 0.1 ≦. i ≦ 0.6 is preferable. Specifically, for example, LiMn PO _{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 _0.3 Fe _0.7 PO ₄ , LiMn _0.5 Fe _0.5 PO ₄ , Li _1.2 Mn _0.63 Fe _0.27 PO ₄ , Li _0.6 Mn _0.84 Fe _0.36 PO _4, etc. Among them, LiMn _0.3 Fe _0.7 PO ₄ , LiMn _0.7 Fe _0.3 PO ₄ , LiMn _0.8 Fe _0.2 PO ₄ , Li _1.2 Mn _0.63 Fe _0.27 PO ₄ , or Li _0.6 Mn _0.84 Fe _0.36 PO ₄ are preferred.

Further, as the lithium-based polyanionic particles (B) represented by the above formula (IV), the positive electrode active material composite (C) for a lithium ion secondary battery obtained by combining with the lithium composite oxide secondary particles (A). ), 0.5 ≦ l ≦ 1.2 is preferable, 0.6 ≦ l ≦ 1.1 is more preferable, 0.65 ≦ l ≦ 1.05 is further preferable, and 0. 1 ≦ k ≦ 0.6 is preferable. Specifically, for example, Li ₂ Fe _0.45 Mn _0.45 Co _0.1 SiO ₄ , Li ₂ Fe _0.36 Mn _0.54 Al _0.066 SiO ₄ , Li ₂ Fe _0.45 Mn _0.45 Zn _0.1 SiO ₄ , Li ₂ Fe _0.36 Mn _0.54 V _0.066 SiO ₄ , Li ₂ Fe _0.282 Mn _0.658 Zr _0.02 SiO ₄ , Li _2.2 Fe _0.252 Mn _0.594 Zr _0.027 SiO ₄ , Li _1.2 Fe _0.392 Mn _0.924 Zr _0.042 SiO _4, etc. Among them, Li ₂ Fe _0.282 Mn _0.658 Zr _0.02 SiO ₄ , Li _2.2 Fe _0.252 Mn _0.594 Zr _0.027 SiO ₄ or Li _2.2 Fe _0.392 Mn _0.924 Zr _0.042 SiO ₄ is preferable.

Further, the lithium-based polyanion particles (B) have a core-shell structure having a core portion (inside) and a shell portion (surface layer portion) composed of lithium-based polyanion particles represented by the above formula (III) or formula (IV). It may contain carbon (c) formed and supported.

Due to the core-shell structure of the lithium-based polyanion particles (B), a lithium-based polyanion having a high Mn content that is easily eluted from the lithium-based polyanion particles (B) into the electrolytic solution is arranged in the core portion, and the shell portion in contact with the electrolytic solution. By arranging a lithium-based polyanion having a low Mn content in the particle, it is possible to further improve the suppression of deterioration of cycle characteristics and the assurance of safety due to the lithium-based polyanion particles. At this time, the core portion may have one phase or may be composed of two or more phases having different compositions. As an embodiment in which the core portion is composed of two or more phases, a structure in which a plurality of phases are concentrically stacked in layers may be used, or a structure in which the composition changes transitionally from the surface of the core portion to the central portion. Good.
Further, the shell portion may be formed on the outside of the core portion, and may be one phase like the core portion, or may be composed of two or more phases having different compositions.

As the lithium-based polyanion particles (B) formed by forming a core-shell structure with two or more kinds of lithium-based polyanion particles having different compositions, specifically, (core part)-(shell part) is, for example, ( LiMnPO ₄ )-(LiFePO ₄ ), (LiMn _0.5 Co _0.5 PO ₄ )-(LiFePO ₄ ), (Li ₂ MnSiO ₄ )-(LiFePO ₄ ), or (Li ₂ MnSiO ₄ )-(Li ₂ FeSiO ₄ ), etc. Particles consisting of.

The formula (III) or an average particle diameter of the lithium-based polyanion particles represented by the formula (IV) (B) (R B) ( secondary particles), electrode density improvement of handling and electrode coating during electrode fabrication From the viewpoint of construction, it is preferably 5 μm to 30 μm, and more preferably 7 μm to 20 μm.
The average primary particle size (average particle size of the primary particles constituting the secondary particles) of the lithium-based polyanionic particles (B) represented by the above formula (III) or the above formula (IV) is the lithium composite oxide secondary particles. From the viewpoint of densely complexing with the lithium composite oxide particles (a) only on the surface of (A), it is preferably 50 nm to 500 nm, and more preferably 50 nm to 300 nm.
The core - the average particle size of the formed shell structure comprising lithium polyanion particles _(B) (R B) is preferably 5 m to 30 m, more preferably 7Myuemu～20myuemu.

The lithium ion conductivity of the lithium-based polyanionic particles (B) represented by the above formula (III) or formula (IV) when pressurized at 20 MPa at 25 ° C. is 1 × 10 ^-7 S / cm or more. It is preferably 1 × 10 ^-6 S / cm or more, and more preferably 1 × 10 -6 S / cm or more. The upper limit of the lithium ion conductivity of the lithium-based polyanionic particles (B) is not particularly limited.

The lithium-based polyanion particles (B) contain supported carbon (c). The carbon (c) is supported on the surface of the lithium-based polyanion particles (B). When the lithium-based polyanion particles (B) are represented by the formula (III), the supported amount of the carbon (c) is 100 mass by mass of the total amount of the supported carbon (c) -containing lithium-based polyanion particles (B). In%, it is preferably 0.1% by mass or more and less than 10% by mass, more preferably 0.1% by mass to 7% by mass, and further preferably 0.1% by mass to 5% by mass. When the lithium-based polyanion particles (B) are represented by the formula (IV), the total amount of the lithium-based polyanion particles (B) containing the supported carbon (c) is 100% by mass, preferably 0. It is 1% by mass or more and less than 20% by mass, more preferably 0.5% by mass to 15% by mass, and further preferably 1% by mass to 10% by mass.

The supported carbon (c) contained in the lithium-based polyanionic particles (B) represented by the above formula (III) or the formula (IV) includes cellulose nanofibers and / or lignocellulose nanofibers described later. (Hereinafter, these may be collectively referred to as "CNF".) It is preferable to use carbon (c1) derived from carbon (c1) or carbon (c2) derived from a water-soluble carbon material, or a combination of carbon (c1) and carbon (c2). .. In this case, the amount of carbon (c) supported in the lithium-based polyanion particles (B) is the total amount of carbon of carbon (c1) derived from CNF and carbon (c2) derived from the water-soluble carbon material. , Corresponds to the carbon atom equivalent amount of the CNF or the water-soluble carbon material which is the carbon source.

The cellulose nanofibers contained in the lithium-based polyanion particles (B) and which serve as the carbon source (c'1) of the supporting carbon (c1) are skeletal components that occupy about 50% of all plant cell walls. Therefore, it is a lightweight and high-strength fiber that can be obtained by defibrating the plant fibers constituting such a cell wall to a nano size. Further, like the cellulose nanofibers, the lignocellulose nanofibers serving as a carbon source (c'1) are cellulose nanofibers obtained without purification for removing lignin, and the cellulose nanofibers are lignin. It is covered.
Both of these cellulose nanofibers and lignocellulose nanofibers have excellent dispersibility in water.

CNF-derived carbon (c1) has a periodic structure. The fiber diameter of such CNF is 1 nm to 100 nm, and it also has good dispersibility in water. Further, since the cellulose molecular chain constituting CNF has a periodic structure made of carbon, it is firmly supported on the surface of the lithium-based polyanion particles (B) while being carbonized together with the polyanion particles. Therefore, it is possible to impart electron conductivity to these polyanion particles and obtain a useful positive electrode active material composite for a lithium ion secondary battery having excellent cycle characteristics.

The water-soluble carbon material as the carbon source (c'2) of the carbon (c2) derived from the supported water-soluble carbon material contained in the lithium-based polyanion particles (B) is 100 g of water at 25 ° C. It means a carbon material that dissolves 0.4 g or more, preferably 1.0 g or more in terms of carbon atom equivalent of the water-soluble carbon material, and is present as carbon on the surface of the lithium-based polyanion particles (B) by being carbonized. It becomes. Examples of such a water-soluble carbon material include one or more selected from sugars, polyols, polyethers, and organic acids. More specifically, for example, monosaccharides such as glucose, fructose, galactose, mannose; disaccharides such as maltose, sucrose, cellobiose; polysaccharides such as starch and dextrin; ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, butane. Polyols and polyethers such as diol, propanediol, polyvinyl alcohol and glycerin; organic acids such as sucrose, tartrate and ascorbic acid can be mentioned. Among them, glucose, fructose, sucrose, and dextrin are preferable, and glucose is more preferable, from the viewpoint of enhancing the solubility and dispersibility in a solvent and effectively functioning as a carbon material.

The amount of carbon (c) supported on the surface of the lithium-based polyanion particles (B) (when the carbon (c) is carbon (c1) derived from CNF or carbon (c2) derived from a water-soluble carbon material). , These carbon atom equivalent amounts) can be confirmed as the amount of carbon measured by using a carbon / sulfur analyzer for the lithium-based polyanion particles (B).

Further, the lithium-based polyanion particles (B) represented by the above formula (III) or the formula (IV) may be composited with the primary particles (a) which are lithium composite oxide particles, and are lithium composite oxide particles. It may be directly composited with a part of the lithium composite oxide secondary particles (A) formed by aggregating certain primary particles.

Further, in the present invention, in the compounding treatment of the above-mentioned lithium composite oxide secondary particles (A) and lithium-based polyanionic particles (B), a water-insoluble carbon powder (c3) other than CNF-derived carbon (c1) is used as a carbon source. ) May be mixed at the same time and combined with the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). 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 (relative to 100 g of water at 25 ° C.) other than the carbon (c1) derived from CNF. It is a carbon powder having conductivity with a dissolved amount of less than 0.4 g in terms of carbon atom equivalent of the water-insoluble carbon powder (c3). By combining the water-insoluble carbon powder (c3), the water-insoluble carbon powder (c3) becomes the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (A) in the positive electrode active material composite for the lithium ion secondary battery. The degree of these composites is increased while interposing in the gap of B) or existing so as to cover the plurality of lithium-based polyanion particles (B) on the surface of the positive electrode active material composite for the lithium ion secondary battery. By strengthening, it is possible to effectively suppress the separation of the lithium-based polyanion particles (B) from the lithium composite oxide secondary particles (A).

Examples of the water-insoluble carbon powder (c3) include graphite, amorphous carbon (Ketjen black, acetylene black, etc.), nanocarbon (graphene, fullerene, etc.), conductive polymer powder (polyaniline powder, polyacetylene powder, polythiophene powder, etc.). , Polypyrrole powder, etc.), etc., or two or more of them. Among them, graphite, acetylene black, graphene, and polyaniline powder are preferable, and graphite is more preferable, from the viewpoint of reinforcing the degree of compounding of the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). The graphite may be artificial graphite (scaly, lumpy, earthy, graphene) or natural graphite.

The average particle size of the water-insoluble carbon powder (c3) is preferably 0.5 μm to 20 μm, more preferably 1.0 μm to 15 μm, from the viewpoint of handling in the manufacturing process and strong composite.

Water that is simultaneously mixed and composited when the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) are composited in the positive electrode active material composite for a lithium ion secondary battery of the present invention. The content of the insoluble carbon powder (c3) is preferably 0.5 parts by mass to 25 parts by mass with respect to 100 parts by mass of the total amount of the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). Yes, more preferably 1 part by mass to 11 parts by mass, and even more preferably 1 part by mass to 10 parts by mass.

Further, the total amount of the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) containing the supported carbon (c) and the carbon supported on the lithium-based polyanion particles (B). The mass ratio (((A) + (B)) :( c)) of (c1 and / or c2) and the total content (c) of the water-insoluble carbon powder (c3) is preferably 99.5: 0. .5 to 80:20, more preferably 99: 1 to 90:10.

Further, a positive electrode active material composite for a lithium ion secondary battery in which lithium-based polyanionic particles (B) containing carbon (c) supported on the surface of the lithium composite oxide secondary particles (A) are composited. Mass ratio of the content of the lithium composite oxide secondary particles (A) in C) to the content of the lithium-based polyanionic particles (B) containing carbon (c) (including the amount of carbon (c) supported). ((A): (B)) is preferably 95: 5 to 55:45, more preferably 90: 10 to 70:30.

Then, the surface of the lithium composite oxide secondary particles (A) is coated with the lithium-based polyanion particles (B) containing the supported carbon (c), which is a positive electrode active material for a lithium ion secondary battery. the average particle diameter of the complex _(C) (R C) is preferably 1.2Myuemu～19myuemu, more preferably 6Myuemu～15.4Myuemu.

Next, a lithium-based polyanion formed by blending the positive electrode active material composite (C) for a lithium ion secondary battery with the mass ratio ((B') :( C)) = 91: 9 to 50:50. The particle (B') will be described.

The lithium-based polyanion particles (B') have the same physical properties and composition as the lithium-based polyanion particles (B) represented by the above formula (III) or formula (IV), and contain carbon (c) supported. It is a particle. That is, the lithium-based polyanion particles (B) are particles that form the positive electrode active material composite (C) for the lithium ion secondary battery, and are particles inherent in the composite (C). On the other hand, the lithium-based polyanion particles (B'), together with the positive electrode active material composite (C) for the lithium ion secondary battery and the lithium composite oxide secondary particles (A'), are the mixed positive electrode activity for the lithium ion secondary battery. It is a particle that forms a substance and is a particle that is extrinsic in the complex (C).
Therefore, the lithium-based polyanionic particles (B') need only have values within the same range as the lithium-based polyanionic particles (B) with respect to the average particle size and the lithium ion conductivity, and have the same core-shell structure. It may be presented.

However, the ratio of the present invention, the 'average particle diameter of the (R B average particle size (R _C) and lithium polyanion particles of the positive electrode active material composite for a lithium ion secondary battery _{(C) (B)')} ( _RC / R _B' ) is 0.2 to 0.98 from the viewpoint of effectively increasing the discharge capacity per volume by increasing the electrode density and effectively suppressing the deterioration of cycle characteristics over a long period of time. It is preferably 0.3 to 0.95, and more preferably 0.4 to 0.93.

The average particle diameter of the lithium composite oxide secondary particle (A) and (R _A), the ratio of the 'average particle diameter of the (R B lithium polyanion particles _{(B)') (R A} / R B ') Is preferably 0.03 to 0.79, more preferably 0.25 to 0.77, and even more preferably 0.35 to 0.75, from the viewpoint of increasing the electrode density.

In the mixed positive electrode active material (D) for a lithium ion secondary battery of the present invention, the content of the lithium-based polyanionic particles (B') compounded and the positive electrode active material composite for a lithium ion secondary battery ( The mass ratio ((B') :( C)) to the content of C) is 91: 9 to 50:50, preferably 89: 11 to 50:50, and more preferably 80:20. ~ 50:50.
If the mass ratio ((B'): (C)) is out of the above range, it becomes difficult to suppress the reaction between the lithium composite oxide secondary particles (A') and the electrolytic solution, and the discharge capacity associated with charging and discharging becomes difficult. May hinder the improvement of long-term cycle characteristics.

Further, in the mixed positive electrode active material (D) for the lithium ion secondary battery, the lithium composite oxide secondary particles (A) constituting the positive electrode active material composite (C) for the lithium ion secondary battery and the above. Mass ratio to the total content of the lithium-based polyanion particles (B) and the lithium-based polyanion particles (B') constituting the positive electrode active material composite (C) for the lithium ion secondary battery (((A): (((A) :( B) + (B'))) is preferably 47.5: 52.5 to 5:95, more preferably 47.5: 52. From the viewpoint of discharge capacity per unit volume and long-term cycle characteristics. It is 5 to 6:94, more preferably 47.5: 52.5 to 10:90.

In order to produce the mixed positive electrode active material (D) for a lithium ion secondary battery of the present invention, the positive electrode active material composite (C) for a lithium ion secondary battery and the lithium-based polyanionic particles (B') are used. However, the respective addition amounts may be adjusted and mixed so that the mass ratio ((B'): (C)) = 91: 9 to 50:50.
Specifically, lithium obtained by mixing lithium composite oxide secondary particles (A) and lithium-based polyanion particles (B) in which carbon (c) is supported while applying compressive force and shearing force. A step of mixing lithium-based polyanion particles (B') with the positive electrode active material composite (C) for an ion secondary battery may be provided.

The process of mixing the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) carrying the carbon (c) while applying compressive force and shearing force is performed in a closed container equipped with an impeller. It is preferable to do so. The processing time and / or the peripheral speed of the impeller when performing the mixing process while applying the compressive force and the shearing force are supported by the lithium composite oxide secondary particles (A) and carbon (c) to be charged into the container. It is necessary to appropriately adjust according to the total amount of the lithium-based polyanion particles (B) formed.

For example, when the process of mixing while applying the compressive force and the shearing force is performed for 5 to 90 minutes in a closed container equipped with an impeller rotating at a peripheral speed of 15 m / s to 45 m / s, the lithium composite charged into the container is used. The total amount of the secondary oxide particles (A) and the lithium-based polyanion particles (B) on which the carbon (c) is supported is the effective container (the portion of the closed container provided with the impeller that can accommodate the mixing object). It is preferably 0.1 g to 0.7 g, and more preferably 0.15 g to 0.4 g per ^{1 cm 3 (} container corresponding to).

The peripheral speed of the impeller is preferably 15 m / s to 45 m / s, more preferably 15 m / s to 35 m / s, from the viewpoint of increasing the tap density of the obtained positive electrode active material composite for a lithium ion secondary battery. Is. The mixing time is preferably 5 minutes to 90 minutes, more preferably 10 minutes to 80 minutes.
The peripheral speed of the impeller means the speed of the outermost end of the rotary stirring blade (impeller), which can be expressed by the following formula (2), and is mixed while applying a compressive force and a shearing force. The processing time may vary depending on the peripheral speed of the impeller so that the slower the peripheral speed of the impeller, the longer the processing time.
Impeller peripheral speed (m / s) =
Impeller radius (m) x 2 x π x rotation speed (rpm) ÷ 60 ... (2)

Examples of the device provided with the closed container capable of easily performing the compounding process while applying such compressive force and shearing force include a high-speed shear mill, a blade type kneader, and the like. Specific examples thereof include, for example. Particle design equipment COMPOSI, Mechanohybrid, High-performance flow mixer FM mixer (manufactured by Nippon Coke Industries Co., Ltd.) Fine particle compounding equipment Mechanofusion, Nobilta (manufactured by Hosokawa Micron), Surface modifier Miralo, Hybridization system (Nara Machinery Co., Ltd.) ) Can be preferably used.
As the treatment conditions for the above mixing, the treatment temperature is preferably 5 ° C. to 80 ° C., more preferably 10 ° C. to 50 ° C. The treatment atmosphere is not particularly limited, but is preferably under an inert gas atmosphere or a reducing gas atmosphere.

Lithium-based polyanionic particles (B) in which the carbon (c) is supported on the surface of the lithium composite oxide secondary particles (A), and water-insoluble carbon powder (c3) added as needed. Can be evaluated by X-ray photoelectron spectroscopy (XPS) to the extent that the particles are densely and uniformly dispersed and composited. Specifically, when the obtained positive electrode active material composite (C) for a lithium ion secondary battery is irradiated with soft X-rays of several keV, the portion is formed from the portion irradiated with the soft X-rays. Since photoelectrons having an energy value peculiar to the element are emitted, the peak intensity corresponding to trivalent Ni obtained by analyzing the peak of _{Ni2p 3/2} emitted from the lithium composite oxide secondary particle (A) is emitted. By comparing the sum of the peak intensities of P2p or Si2P released from the lithium-based polyanion particles (B) and C1s released from the carbon (c), the positive electrode active material composite for the lithium ion secondary battery It can be seen that the area ratio of the material on the surface, that is, the degree to which the lithium-based polyanion particles (B) and the water-insoluble carbon powder (c3) cover the lithium composite oxide secondary particles (A). However, since the lithium-based polyanion particles (B) may contain trivalent Ni, _{the peak intensity of Ni2p 3/2} of the lithium composite oxide secondary particles (A) indicates that the lithium composite oxide secondary particles ( P2p or Si2P the normalized lithium polyanion particles with respect to the peak (B) derived from a lithium composite oxide secondary particle in the difference XPS profile by subtracting the peak of Ni2p _3/2 of a) (a) derived from Ni2p ₃ Use a peak intensity of _{/ 2.} This peak intensity ratio (Ni2p _3/2 trivalent Ni peak intensity) / ((P2p peak intensity) + (C1s peak intensity)) or (Ni2p _3/2 trivalent Ni peak intensity) / ((Peak intensity of Si2p) + (Peak intensity of C1s)) is preferably 0.1 or less, more preferably 0.01 or less. With such a peak intensity ratio, the surface of the obtained positive electrode active material composite (C) for a lithium ion secondary battery is the surface of the lithium composite oxide secondary particles (A), and the lithium composite oxide particles (a) are on the surface. It is densely covered with lithium-based polyanion particles (B) and water-insoluble carbon powder (c3), which are composited with carbon (c).

Next, the obtained positive electrode active material composite (C) for a lithium ion secondary battery and lithium-based polyanionic particles (B') are mixed using a well-known powder mixing method, for example, a Nautamixer or a Henshell mixer. As a result, the mixed positive electrode active material (D) for a lithium ion secondary battery may be obtained.

A positive electrode for a lithium ion secondary battery can be obtained by using a well-known conductive agent and a binder with a well-known formulation together with the mixed positive electrode active material (D) for a lithium ion secondary battery of the present invention. it can. Specifically, for example, the mixed positive electrode active material (D) for a lithium ion secondary battery, a conductive auxiliary agent such as carbon black, and a binder such as polyvinylidene fluoride or styrene butadiene rubber (SBR) can be added to N. -A solvent such as methyl-2-pyrrolidone may be added and kneaded sufficiently to prepare a positive electrode paste, the paste may be applied onto a current collector such as aluminum foil, then compacted with a roller press or the like, and then dried. ..

Further, the positive electrode paste can be directly prepared using a predetermined material without obtaining the mixed positive electrode active material (D) for a lithium ion secondary battery in advance. Specifically, the amount satisfies the mass ratio ((B') :( C)) = 91: 9 to 50:50 with respect to the positive electrode active material composite (C) for the lithium ion secondary battery. While blending lithium-based polyanionic particles (B'), other positive electrode mixture constituent materials such as a solvent are further added to and mixed with the conductive auxiliary agent and the binder to prepare the mixture. That is, the positive electrode active material composite (C) for a lithium ion secondary battery, lithium-based polyanionic particles (B'), a conductive auxiliary agent, a binder, a solvent, and the like can be mixed all at once or sequentially mixed as appropriate. it can.

The thickness of the obtained positive electrode mixture layer is preferably 20 μm to 500 μm from the viewpoint of optimizing the long-term cycle characteristics of the lithium ion secondary battery.

The amount of water contained in the positive electrode for a lithium ion secondary battery of the present invention is preferably small, specifically 800 ppm or less. In order to reduce the water content, a method of drying the electrode paste in a high temperature environment or a reduced pressure environment, or a method of electrochemically decomposing the water contained in the obtained positive electrode for a lithium ion secondary battery is used. Just do it.

The lithium ion secondary battery using the positive electrode for the lithium ion secondary battery of the present invention is not particularly limited as long as it has a positive electrode, a negative electrode, an electrolytic solution, and a separator as essential configurations.

Here, as for the negative electrode, as long as lithium ions can be occluded at the time of charging and released at the time of discharging, the material composition is not particularly limited, and a known material composition can be used. For example, a carbon material such as lithium metal, graphite, silicon-based (Si, SiO _x ), lithium titanate, or amorphous carbon can be used. Then, it is preferable to use an electrode formed of an intercalate material capable of electrochemically occluding and releasing lithium ions, particularly a carbon material. Further, two or more kinds of the above-mentioned negative electrode materials may be used in combination, and for example, a combination of graphite and silicon can be used.

The electrolytic solution is a solution 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 usually used for an electrolytic solution of a lithium ion secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones, etc. , Oxolan compounds and the like can be used.

The type of supporting salt is not particularly limited, but is _{an inorganic salt selected from LiPF 6} , LiBF ₄ , LiClO ₄ and LiAsF ₆ , derivatives of the inorganic salt, LiSO ₃ CF ₃ , LiC (SO ₃ CF _3). ) ₂ and an organic salt selected from 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 ), and derivatives of the organic salt. It is preferable that it is at least one of.

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

The shape of the lithium ion secondary battery having the above configuration is not particularly limited, and may be various shapes such as a coin type, a cylindrical type, and a square type, or an indefinite shape enclosed in a laminated outer body. ..

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

After producing positive electrodes using the positive electrode pastes obtained in all Examples and Comparative Examples, the discharge capacity and cycle characteristics of the secondary battery using the obtained positive electrodes were evaluated. The method for manufacturing the positive electrode, the discharge capacity, and the method for evaluating the cycle characteristics are shown below.

≪Manufacturing of positive electrode≫
The obtained positive electrode paste was applied to a current collector made of an aluminum foil having a thickness of 20 μm, and vacuum dried at 80 ° C. for 12 hours. Then, it was punched into a disk shape having a diameter of 14 mm and pressed at 16 MPa for 2 minutes using a hand press to obtain a positive electrode. Next, a coin-type secondary battery was constructed using the above-mentioned positive electrode. For the negative electrode, a lithium foil punched to φ15 mm was used. As the electrolytic solution, one in which LiPF6 was dissolved at a concentration of 1 mol / L in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 3: 7 was used. As the separator, a known material such as a polymer porous film such as polypropylene was used. These battery parts were incorporated and housed by a conventional method in an atmosphere having a dew point of −50 ° C. or lower to obtain a coin-type secondary battery (CR-2032).

≪Measurement of electrode density≫
The mass and thickness of the positive electrode produced by the above method were measured to calculate ^{the electrode density (g / cm 3).} The results are shown in Table 1.

≪Measurement of discharge capacity≫
With a discharge capacity measuring device (HJ-1001SD8, manufactured by Hokuto Denko Co., Ltd.), a constant current charge with a current density of 34 mA / g and a voltage of 4.25 V and a current of 34 mA / g and a final voltage of 3.0 V in an environment of 30 ° C. A constant current discharge was used, and the discharge capacity at a current density of 34 mA / g (0.2 CA) was determined. The results are shown in Table 1.

≪Evaluation of cycle characteristics≫
Using a discharge capacity measuring device (same as above), constant current charging with a current density of 85 mA / g and a voltage of 4.25 V and constant current discharge with a current density of 85 mA / g and a final voltage of 3.0 V were used, and a current density of 85 mA / g (0). The discharge capacity at .5CA) was determined. Further, a 2000 cycle repeated test under the same charge / discharge conditions was carried out, and the capacity retention rate (%) was determined by the following formula (1). All charge / discharge tests were performed at 30 ° C. The results are shown in Table 1.
Capacity retention rate (%) = (discharge capacity after 2000 cycles) /
(Discharge capacity after one cycle) x 100 ... (1)

[Production Example 1: Production of secondary particles (NCM-A1) of NCM-based composite oxide]
After mixing 473 g of nickel sulfate hexahydrate, 169 g of cobalt sulfate heptahydrate, 145 g of manganese sulfate pentahydrate, and 3 L of water so that the molar ratio of Ni: Co: Mn is 6: 2: 2. 25% aqueous ammonia was added dropwise to the mixed solution at a dropping rate of 300 mL / min to obtain 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 a metal composite hydroxide, and then 37 g of lithium carbonate was mixed with the mixture b1 with a ball mill to obtain a powder mixture c1. The obtained powder mixture c1 was calcined by calcination at 800 ° C. for 4 hours in an air atmosphere, and then calcined at 800 ° C. for 11 hours in an air atmosphere as the main firing, and the secondary particles of the NCM-based composite oxide were fired. A1 (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , average primary particle size: 250 nm, average particle size: 11.8 μm) was obtained.
Hereinafter, the secondary particles A1 of the NCM-based composite oxide will be referred to as NCM-A1.

[Production Example 2: Production of secondary particles (NCM-A2) of NCM-based composite oxide]
The powder mixture C1 of Production Example 1 is calcined by calcination at 800 ° C. for 4 hours in an air atmosphere, and then fired at 800 ° C. for 4 hours in an air atmosphere as the main firing to obtain two NCM-based composite oxides. Secondary particles A2 (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , average primary particle size: 250 nm, average particle size: 4.8 μm) were obtained.
Hereinafter, the secondary particles A2 of the NCM-based composite oxide will be referred to as NCM-A2.

[Production Example 3: Production of secondary particles (NCA-A3) of NCA-based composite oxide]
Lithium carbonate 370 g, nickel carbonate 950 g, cobalt carbonate 150 g, aluminum carbonate 58 g, and 3 L of water are mixed so that the molar ratio of Li: Ni: Co: Al is 1: 0.8: 0.15: 0.05. After that, the mixture was mixed with a ball mill to obtain a powder mixture a3. The obtained powder mixture a3 was calcined by calcination at 800 ° C. for 5 hours in an air atmosphere, and then calcined at 800 ° C. for 24 hours in an air atmosphere as the main firing, and the secondary particles of the NCA-based composite oxide were fired. A3 (LiNi _0.8 Co _0.15 Al _0.05 O ₂ , average primary particle size: 300 nm, average particle size: 10.0 μm) was obtained.
Hereinafter, the secondary particles A3 of the NCA-based composite oxide will be referred to as NCA-A3.

[Production Example 4: Production of Lithium-based Polyanion Particles (LMP-B1)]
1272 g of LiOH · H ₂ O and 4 L of water were mixed to obtain 1 slurry. Next, 1153 g of an 85% aqueous phosphoric acid solution was added dropwise at 35 mL / min while stirring the obtained slurry x1 for 3 minutes while maintaining the temperature at 25 ° C., followed by cellulose nanofibers (Wma-1002, Sugino Machine Limited). 5892 g (with a fiber diameter of 4 to 20 nm) was added and stirred at a speed of 400 rpm for 12 hours to obtain a slurry y1 containing _{Li 3} PO _4. And the resulting nitrogen purge slurry y1, added after the dissolved oxygen concentration of the slurry y1 was 0.5 mg / L, with respect to the slurry y1 total _{amount, MnSO 4 · 5H 2 O 1688g} , the FeSO ₄ · 7H ₂ O 834g To obtain slurry z1. The molar ratio of MnSO ₄ to FeSO ₄ added (manganese compound: iron compound) was 70:30.
Next, the obtained slurry z1 was put into an autoclave, and a hydrothermal reaction was carried out at 170 ° C. for 1 hour. The pressure in the autoclave was 0.8 MPa. After the hydrothermal reaction, the produced 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 freeze-dried at −50 ° C. for 12 hours to obtain complex Cz1. 1000 g of the obtained complex Cz1 was taken, and 1 L of water was added thereto to obtain a slurry Ez1. The obtained slurry Ez1 is dispersed with an ultrasonic stirrer (T25, manufactured by IKA) for 1 minute to uniformly color the whole, and then a spray dry device (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.) is used. The granulated body Fz1 was obtained by spray-drying (nozzle air flow rate 35 L / min, air supply temperature 180 ° C.). The obtained granulated material Fz1 was calcined at 700 ° C. for 1 hour in an argon hydrogen atmosphere (hydrogen concentration 3%) to carry 2.0% by mass of carbon derived from cellulose nanofibers. Secondary particles B1 (LiMn _0.7 Fe _0.3 PO ₄ , amount of carbon = 2.0% by mass, average primary particle size: 100 nm, average particle size: 15.8 μm) were obtained.
Hereinafter, the secondary particles B1 of lithium manganese iron phosphate will be referred to as LMP-B1.

[Production Example 5: Production of Lithium-based Polyanion Particles (LMP-B2)]
And the MnSO ₄ · 5H ₂ O is added 723 g, the FeSO ₄ · 7H ₂ O to 1946G, the molar ratio of MnSO ₄ and FeSO _4: except that (manganese compound iron compound) was 30:70, the same manner as in Production Example 4 Then, secondary particles B2 (LiMn _0.3 Fe _0.7 PO ₄ , carbon amount = 2.0% by mass, average primary particle size: 100 nm, average particle size: 15.5 μm) of lithium manganese iron phosphate were obtained.
Hereinafter, the secondary particles B2 of lithium manganese iron phosphate will be referred to as LMP-B2.

[Production Example 6: Production of Lithium-based Polyanion Particles (LMP-B3)]
600 g of the composite Cz1 was taken, and the spray-drying conditions were the same as in Production Example 4 except that the nozzle air flow rate was 80 L / min and the supply air temperature was 120 ° C. LiMn _0.7 Fe _0.3 PO ₄ , amount of carbon = 2.0% by mass, average primary particle size: 100 nm, average particle size: 4.8 μm) was obtained.
Hereinafter, the secondary particles B3 of lithium manganese iron phosphate will be referred to as LMP-B3.

[Production Example 7: (NCM-A1 55% + LMP-B1 45%) Complex C1]
NCM-A1275g and LMP-B1 225g were compounded at 20 m / s (2600 rpm) for 10 minutes using Mechanofusion (AMS-Lab manufactured by Hosokawa Micron), and complex C1 (average grain size) composed of NCM and LMFP was performed. Diameter: 14.7 μm) was obtained.

[Production Example 8: (NCM-A1 70% + LMP-B1 30%) Complex C2]
A complex C2 (average particle size: 14.2 μm) composed of NCM and LMFP was obtained in the same manner as in Production Example 7 except that NCM-A1 was changed to 350 g and LMP-B1 was changed to 150 g.

[Production Example 9: (NCM-A1 80% + LMP-B1 20%) Complex C3]
A complex C3 (average particle size: 13.9 μm) composed of NCM and LMFP was obtained in the same manner as in Production Example 7 except that NCM-A1 was changed to 400 g and LMP-B1 was changed to 100 g.

[Production Example 10: (NCM-A1 90% + LMP-B1 10%) Complex C4]
A complex C4 (average particle size: 13.3 μm) composed of NCM and LMFP was obtained in the same manner as in Production Example 7 except that NCM-A1 was changed to 450 g and LMP-B1 was changed to 50 g.

[Production Example 11: (NCM-A1 80% + LMP-B2 20%) Complex C5]
A complex C5 (average particle size: 13.7 μm) composed of NCM and LMFP was obtained in the same manner as in Production Example 9 except that LMP-B1 was changed to LMP-B2.

[Production Example 12: (NCM-A2 55% + LMP-B2 45%) Complex C6]
A complex C6 (average particle size: 7.7 μm) composed of NCM and LMFP was obtained in the same manner as in Production Example 7 except that NCM-A1 was changed to NCM-A2.

[Production Example 13: (NCM-A2 80% + LMP-B2 20%) Complex C7]
A complex C7 (average particle size: 6.7 μm) composed of NCM and LMFP was obtained in the same manner as in Production Example 9 except that NCM-A1 was changed to NCM-A2.

[Production Example 14: (NCA-A3 55% + LMP-B1 45%) Complex C8]
A complex C8 (average particle size: 12.9 μm) composed of NCA and LMFP was obtained in the same manner as in Production Example 7 except that NCM-A1 was changed to NCA-A3.

[Production Example 15: (NCA-A3 80% + LMP-B1 20%) Complex C9]
A complex C9 composed of NCA and LMFP was obtained in the same manner as in Production Example 9 except that NCM-A1 was changed to NCA-A3. (Average particle size: 11.9 μm)

[Example 1: Positive electrode active material D1, positive electrode paste A]
80 g of LMP-B1 and 10 g of the complex C1 were mixed with Nautamixer NX-1 (manufactured by Hosokawa Micron Co., Ltd.) for 1 min to obtain a positive electrode active material D1. 100 mg of acetylene black and 2000 mg of 5% polyvinylidene fluoride were placed in a 50 mL screw tube bottle and kneaded with Awatori Rentaro (registered trademark, manufactured by Shinky Co., Ltd.) at 2000 rpm for 10 minutes. To the kneaded paste, 1800 mg of the positive electrode active material D1 was added, and the mixture was kneaded at 2000 rpm for 10 minutes. An appropriate amount of 1-methyl-2-pyrrolidone was added to the paste obtained by kneading the active material, and the paste was kneaded at 2000 rpm for 5 minutes to obtain a positive electrode paste A.

[Example 2: Positive electrode paste B]
100 mg of acetylene black and 2000 mg of 5% polyvinylidene fluoride were placed in a 50 mL screw tube bottle and kneaded with Awatori Rentaro (registered trademark, manufactured by Shinky Co., Ltd.) at 2000 rpm for 10 minutes. To the kneaded paste, 1600 mg of LMP-B1 and 200 mg of complex C1 were added, and the mixture was kneaded at 2000 rpm for 10 min. An appropriate amount of 1-methyl-2-pyrrolidone was added to the paste obtained by kneading the active material, and the paste was kneaded at 2000 rpm for 5 minutes to obtain a positive electrode paste B.

[Comparative Example 1: Positive Electrode Paste C]
A positive electrode paste C was obtained in the same manner as in Example 2 except that LMP-B1 was 1690 mg and complex C1 was NCM-A1 110 mg.

[Comparative Example 2: Positive Electrode Paste D]
A positive electrode paste D was obtained in the same manner as in Example 2 except that LMP-B1 was changed to LMP-B3 and the complex C1 was changed to the complex C6.

Using the electrode pastes obtained in Examples 1 and 2 and Comparative Examples 1 and 2, positive electrodes were produced by the above method, and each measurement and evaluation was performed.
Table 1 shows the above-mentioned predetermined physical properties, and Table 2 shows the results.

表１〜２の結果より、実施例１〜２は、複合体（Ｃ）を含まない比較例１、及び平均粒径比（Ｒ_C／Ｒ_B'）が上記範囲外である比較例２に比して、電極密度が高く、単位体積当たりの放電容量が大きくなるとともに、電極の不均一性が抑制され、サイクル特性が向上することがわかる。

From the results of Tables 1 and 2, Examples 1 and 2 correspond to Comparative Example 1 containing no complex (C) and Comparative Example 2 in which the average particle size ratio ( _RC / R _B' ) is out of the above range. In comparison, it can be seen that the electrode density is high, the discharge capacity per unit volume is large, the non-uniformity of the electrodes is suppressed, and the cycle characteristics are improved.

[Example 3: Positive electrode active material D3, positive electrode paste E]
A positive electrode active material E and a positive electrode paste E were obtained in the same manner as in Example 1 except that LMP-B1 was 67.5 g and the complex C1 was 22.5 g of the complex C3.

[Example 4: Positive electrode active material D4, positive electrode paste F]
A positive electrode active material F and a positive electrode paste F were obtained in the same manner as in Example 1 except that LMP-B1 was 67.5 g and the complex C1 was 22.5 g of the complex C5.

[Example 5: Positive electrode paste G]
A positive electrode paste G was obtained in the same manner as in Example 2 except that LMP-B1 was adjusted to 1350 mg and complex C1 was adjusted to complex C3 450 mg.

[Example 6: Positive electrode paste H]
A positive electrode paste H was obtained in the same manner as in Example 2 except that LMP-B1 was adjusted to 1350 mg and complex C1 was adjusted to complex C5 450 mg.

[Example 7: Positive electrode paste I]
A positive electrode paste I was obtained in the same manner as in Example 2 except that LMP-B1 was adjusted to 1350 mg and complex C1 was adjusted to complex C7 450 mg.

[Example 8: Positive electrode active material D8, positive electrode paste J]
A positive electrode active material J and a positive electrode paste J were obtained in the same manner as in Example 1 except that LMP-B1 was 60 g and the complex C1 was 30 g of the complex C2.

[Example 9: Positive electrode paste K]
A positive electrode paste K was obtained in the same manner as in Example 2 except that LMP-B1 was adjusted to 1200 mg and complex C1 was adjusted to complex C2 600 mg.

[Example 10: Positive electrode active material D10, positive electrode paste L]
A positive electrode active material L and a positive electrode paste L were obtained in the same manner as in Example 1 except that LMP-B1 was 45 g and the complex C1 was 45 g of the complex C4.

[Example 11: Positive electrode paste M]
A positive electrode paste M was obtained in the same manner as in Example 2 except that LMP-B1 was 900 mg and the complex C1 was 900 mg of the complex C4.

[Example 12: Positive electrode active material D12, positive electrode paste N]
A positive electrode active material N and a positive electrode paste N were obtained in the same manner as in Example 1 except that LMP-B1 was 45 g and the complex C1 was 45 g.

[Example 13: Positive electrode paste O]
A positive electrode paste O was obtained in the same manner as in Example 2 except that LMP-B1 was 900 mg and complex C1 was 900 mg.

[Comparative Example 3: Positive Electrode Paste P]
A positive electrode paste P was obtained in the same manner as in Example 2 except that LMP-B1 was 1704 mg and the complex C1 was 96 mg.

[Comparative Example 4: Positive Electrode Paste Q]
A positive electrode paste Q was obtained in the same manner as in Example 2 except that LMP-B1 was 225 mg and complex C1 was complex C3 1575 mg.

Using the positive electrode pastes obtained in Examples 3 to 13 and Comparative Examples 3 to 4, positive electrodes were produced by the above method, and each measurement and evaluation was performed.
Table 3 shows the above-mentioned predetermined physical properties, and Table 4 shows the results.

表３〜４の結果より、実施例３〜１３は、質量比（（Ｂ'）：（Ｃ））が上記範囲外である比較例３〜４に比して、電極密度が向上し、単位体積当たりの放電容量ならびにサイクル特性に優れた電池特性を示すことがわかる。

From the results of Tables 3 to 4, in Examples 3 to 13, the electrode density was improved and the unit was improved as compared with Comparative Examples 3 to 4 in which the mass ratio ((B'): (C)) was out of the above range. It can be seen that the battery exhibits excellent discharge capacity per volume and cycle characteristics.

[Example 14: Positive electrode paste R]
A positive electrode paste R was obtained in the same manner as in Example 2 except that the complex C1 was changed to the complex C8.

[Comparative Example 5: Positive Electrode Paste S]
A positive electrode paste S was obtained in the same manner as in Comparative Example 1 except that the complex C1 was changed to NCA-C3.

[Example 15: Positive electrode paste T]
A positive electrode paste T was obtained in the same manner as in Example 5 except that the complex C1 was changed to the complex C9.

[Comparative Example 6: Positive Electrode Paste U]
A positive electrode paste U was obtained in the same manner as in Comparative Example 3 except that the complex C1 was changed to the complex C8.

[Comparative Example 7: Positive Electrode Paste V]
A positive electrode paste V was obtained in the same manner as in Comparative Example 4 except that the complex C1 was changed to the complex C9.

Using the positive electrode pastes obtained in Examples 14 to 15 and Comparative Examples 5 to 7, a positive electrode was produced by the above method, and each measurement and evaluation was performed.
The above-mentioned predetermined physical properties are shown in Table 5, and the results are shown in Table 6.

表５〜６の結果より、実施例１４及び実施例１５は、複合体（Ｃ）を含まない比較例５、並びに各々同一の複合体（Ｃ）を含みつつも質量比が（（Ｂ'）：（Ｃ））が上記範囲外である比較例６及び比較例７に比して、電極密度が向上し、単位体積当たりの放電容量及びサイクル特性に優れた電池特性を示すことがわかる。

From the results of Tables 5 to 6, Examples 14 and 15 have a mass ratio ((B')) of Comparative Example 5 which does not contain the complex (C) and the same complex (C), respectively. : (C)) is out of the above range, as compared with Comparative Example 6 and Comparative Example 7, it can be seen that the electrode density is improved and the battery characteristics are excellent in the discharge capacity per unit volume and the cycle characteristics.

Claims (7)

The following formula (I):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, 0 ≦. A number satisfying w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3 is shown.)
Alternatively, the following formula (II):
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (II)
(In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, x are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ A number satisfying x ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × x = 3 is shown.)
Only on the surface of the lithium composite oxide secondary particles (A) composed of the lithium composite oxide particles (a) represented by the following formula (III) or formula (IV):
Li _g Mn _h Fe _i M ³ _y PO ₄・ ・ ・ (III)
(In formula (III), M ³ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G, h, i, and y are Satisfy 0 <g ≦ 1.2, 0 ≦ h ≦ 1.2, 0 ≦ i ≦ 1.2, 0 ≦ y ≦ 0.3, and h + i ≠ 0, and g + (valence of Mn) × h + ( Fe valence) x i + (M ³ valence) x y = 3 is shown.)
^{_{Li j Fe k Mn l M 4}} z SiO 4 ··· (IV)
(In formula (IV), M ⁴ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. l and z satisfy 0 <j ≦ 2.4, 0 ≦ k ≦ 1.2, 0 ≦ l ≦ 1.2, 0 ≦ z ≦ 1.2, and k + l ≠ 0, and j + (of Fe). Valuation) × k + (Mn valence) × l + (M ⁴ valence) × z = 4).
A positive electrode active material composite for a lithium ion secondary battery in which lithium-based polyanion particles (B) containing carbon (c) represented by and supported by carbon (c) and lithium composite oxide particles (a) are composited (a positive electrode active material composite for a lithium ion secondary battery). Against C)
Further, the mass ratio ((B') :( C)) = 91 of the lithium-based polyanionic particles (B') represented by the above formula (III) or the formula (IV) and containing the carbon (c) supported. : 9 to 50: average particle diameter of it was blended with 50, and an average particle diameter of the lithium-ion secondary battery positive electrode active material composite _(C) (R C) and lithium polyanion particles (B ') (R _A mixed positive electrode active material for a lithium ion secondary battery having a ratio ( _RC / R _{B') to B') of 0.2 to 0.98.} The mixed positive electrode active material for a lithium ion secondary battery according to claim 1, wherein the lithium-based polyanionic particles (B) have an average particle size of 5 μm to 25 μm. Mass ratio of the content of the lithium composite oxide secondary particles (A) to the total amount of the lithium-based polyanion particles (B) and the lithium-based polyanion particles (B') ((A): ((B) + (B) '))) Is the mixed positive electrode active material for a lithium ion secondary battery according to claim 1 or 2, wherein 47.5: 52.5 to 5:95. In the positive electrode active material composite (C) for a lithium ion secondary battery, the amount of carbon (c) carried is 0.1% by mass or more and less than 20% by mass in 100% by mass of the lithium-based polyanionic particles (B). The mixed positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 3. The carbon (c) supported on the lithium-based polyanion particles (B) and the lithium-based polyanion particles (B') is derived from cellulose nanofibers and / or lignocellulose nanofiber-derived carbon (c1) or a water-soluble carbon material. The mixed positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 4, which is carbon (c2). In the positive electrode active material composite (C) for a lithium ion secondary battery,
The amount of carbon (c) carried is 0.1% by mass or more and less than 20% by mass in 100% by mass of the lithium-based polyanionic particles (B), and the content of the lithium composite oxide secondary particles (A) and lithium. The lithium ion II according to any one of claims 1 to 5, wherein the mass ratio ((A): (B)) to the content of the system polyanion particles (B) is 95: 5 to 55:45. Mixed positive electrode active material for next battery. The following formula (I):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (I)
In formula (I), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, 0 ≦. A number satisfying w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3 is shown.)
Alternatively, the following formula (II):
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (II)
(In formula (II), M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Indicates one or more elements selected from Ge. D, e, f, x are 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ A number satisfying x ≦ 0.3 and 3d + 3e + 3f + ( ^{valence of M 2} ) × x = 3 is shown.)
Only on the surface of the lithium composite oxide secondary particles (A) composed of the lithium composite oxide particles (a) represented by the following formula (III) or formula (IV):
Li _g Mn _h Fe _i M ³ _y PO ₄・ ・ ・ (III)
(In formula (III), M ³ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. G, h, i, and y are Satisfy 0 <g ≦ 1.2, 0 ≦ h ≦ 1.2, 0 ≦ i ≦ 1.2, 0 ≦ y ≦ 0.3, and h + i ≠ 0, and g + (valence of Mn) × h + ( Fe valence) x i + (M ³ valence) x y = 3 is shown.)
^{_{Li j Fe k Mn l M 4}} z SiO 4 ··· (IV)
(In formula (IV), M ⁴ represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. l and z satisfy 0 <j ≦ 2.4, 0 ≦ k ≦ 1.2, 0 ≦ l ≦ 1.2, 0 ≦ z ≦ 1.2, and k + l ≠ 0, and j + (of Fe). Valuation) × k + (Mn valence) × l + (M ⁴ valence) × z = 4).
A positive electrode active material composite for a lithium ion secondary battery in which lithium-based polyanion particles (B) containing carbon (c) represented by and supported by carbon (c) and lithium composite oxide particles (a) are composited (a positive electrode active material composite for a lithium ion secondary battery). Against C)
Further, the mass ratio ((B') :( C)) = 91 of the lithium-based polyanion particles (B') represented by the above formula (III) or the formula (IV) and containing the carbon (c) supported. A method for producing a positive electrode for a lithium ion secondary battery, comprising a step of blending at a ratio of 9 to 50:50, blending a conductive auxiliary agent and a binder, and preparing a positive electrode paste.
The positive electrode active material composite for a lithium ion secondary battery average particle diameter of _(C) (R C) and 'average particle diameter of the (R B lithium polyanion particles _(B)') ratio of (R _C / R B _' ) Is 0.2 to 0.98, a method for manufacturing a positive electrode for a lithium ion secondary battery.