JP2021086723A - Positive electrode active material composite for lithium ion secondary battery and manufacturing method thereof - Google Patents

Abstract

To provide a positive electrode active material composite for a lithium ion secondary battery capable of realizing a lithium ion secondary battery having good discharge capacity and rate characteristics while using lithium composite oxide particles.SOLUTION: In a positive electrode active material composite for a lithium ion secondary battery, lithium positive electrode active material particles (B) represented by a specific formula are supported on the surface of lithium composite oxide secondary particles (A) composed of lithium composite oxide particles represented by a specific formula, and a lithium-based solid electrolyte (C) is supported on the surface of the lithium positive electrode active material particles (B).SELECTED DRAWING: None

Description

The present invention relates to a cathode active material composite for a lithium ion secondary battery and a method for producing the same, in order to obtain a lithium ion secondary battery having excellent discharge capacity and rate characteristics.

Lithium composite oxide is used as a positive electrode active material capable of forming a high output and high capacity lithium ion secondary battery, but in a lithium ion secondary battery using such a lithium composite oxide as a positive electrode active material, it is usually used. The capacity of the battery decreases as the charge / discharge cycle is repeated, and the capacity of the battery may decrease significantly, especially after long-term use. It is considered that the cause of this is that the transition metal component elutes into the electrolytic solution during charging, so that the crystal structure of the lithium composite oxide is likely to be destroyed. Further, when the crystal structure of the lithium composite oxide is destroyed, 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.

Under these circumstances, various positive electrode active materials have been developed in order to realize a lithium ion secondary battery having better battery characteristics. For example, in Patent Document 1 _{, Li 1+ is described on} the surface of lithium transition metal oxide particles represented by _{Li (1 + a)} (Ni _1-bc M _b Co _c ) O _{2 (M is a predetermined metal). x M'x} M'' _2-x (PO ₄ ) ₃ (M'and M'' are predetermined metals) Lithium metal Phosphate nanoparticles are arranged to form a positive electrode active material for a secondary battery. It has been disclosed to improve the high capacity, thermal safety and high temperature life characteristics of secondary batteries. Further, Patent Document 2 describes a positive electrode activity in which a coating layer containing a solid electrolyte containing Li, La, Al, Zr, etc. is provided on the surface of active material particles containing a lithium composite oxide containing nickel as a main component. The substance is disclosed, and attempts are made to improve the cycle characteristics while maintaining the discharge capacity of the non-aqueous secondary battery.
As described above, in all the documents, various battery characteristics are improved by the positive electrode active material in which the surface of the so-called lithium composite oxide particles is coated with lithium ion solid electrolyte particles.

Special Table 2018-517243 JP-A-2019-3786

However, according to the studies by the present inventors, even with the positive electrode active material described in the above patent document, there is room for further improvement in order to sufficiently enhance the discharge capacity and the rate characteristics when the lithium ion secondary battery is formed. It turned out that there was.

Therefore, an object of the present invention is to provide a positive electrode active material composite for a lithium ion secondary battery capable of realizing a lithium ion secondary battery having good discharge capacity and rate characteristics while using lithium composite oxide particles. To do.

Therefore, as a result of diligent studies to solve the above problems, the present inventors have found that the specific lithium positive electrode active material particles (B) are supported on the surface of the specific lithium composite oxide secondary particles (A). At the same time, if it is a positive electrode active material composite for a lithium ion secondary battery in which a lithium-based solid electrolyte (C) is supported on the surface of the lithium positive electrode active material particles (B), the lithium ion secondary battery can be obtained. It has been found that it becomes possible to effectively improve the discharge capacity and the rate characteristics.

Therefore, the present invention has the following formula (1) or formula (2):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (1)
(In the formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number that satisfies 0 ≦ w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3.
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (2)
(In the formula (2), 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.)
On the surface of the lithium composite oxide secondary particles (A) composed of lithium composite oxide particles represented by, the following formula (3), formula (4), formula (5), or formula (6):
LiM ³ _g Co _h O ₂・ ・ ・ (3)
(In the formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) Among them, g and h indicate numbers satisfying 0 ≦ g ≦ 0.1, 0 <h ≦ 1, and ( ^{valence of M 3} ) × g + 3h = 3).
LiM ⁴ _i Mn _j O ₄ ... (4)
(In the formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In the formula (4), i and j represent numbers satisfying 0 ≦ i ≦ 0.1, 0 <j ≦ 2, and ( ^{valence of M 4} ) × i + (valence of Mn) × j = 7. .)
LiNi _k Mn _1-k O ₄ ... (5)
(In equation (5), k indicates a number satisfying 0.3 ≦ k ≦ 0.7.)
Li ₂ MnO _3- LiM ⁶ O ₂ ... (6)
In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. Indicates one or more elements selected from.)
The positive electrode activity for a lithium ion secondary battery is supported by the lithium positive electrode active material particles (B) represented by, and the lithium-based solid electrolyte (C) is supported on the surface of the lithium positive electrode active material particles (B). It provides a material complex (D).

Further, in the present invention, the following steps (I) to (III):
(I) After preparing a slurry (a-1) having a solid content concentration of 20% by mass to 65% by mass, which contains the lithium positive electrode active material particles (B) and the raw material compound of the lithium-based solid electrolyte (C), hot air is used. The granulated product (a) is spray-dried under the condition that the ratio (G / S) of the supply amount G (L / min) of the slurry (a-1) to the supply amount S (L / min) of the slurry (a-1) is 500 to 10000. The process of getting
(II) The obtained granulated product (a) is fired at 500 ° C. to 800 ° C. for 10 minutes to 3 hours, and the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface. ) To obtain a preliminary granulated product (b) having a void ratio of 45% to 80% by volume, and (III) the obtained preliminary granulated product (b) and lithium composite oxide secondary particles (A). ) Is mixed while applying compressive force and shearing force to crush the preliminary granulated product (b), and the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface. ) And the lithium composite oxide secondary particles (A) are combined with the above-mentioned positive electrode active material composite (D) for a lithium ion secondary battery.

According to the positive electrode active material composite for a lithium ion secondary battery of the present invention, the lithium positive electrode active material particles carrying the lithium-based solid electrolyte are effectively supported on the surface of the lithium composite oxide secondary particles. A lithium ion secondary battery having good discharge capacity and rate characteristics can be realized.

Hereinafter, the present invention will be described in detail.
The positive electrode active material composite (D) for a lithium ion secondary battery of the present invention has the following formula (1) or formula (2):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (1)
(In the formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number that satisfies 0 ≦ w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3.
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (2)
(In the formula (2), 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.)
On the surface of the lithium composite oxide secondary particles (A) composed of lithium composite oxide particles represented by, the following formula (3), formula (4), formula (5), or formula (6):
LiM ³ _g Co _h O ₂・ ・ ・ (3)
(In the formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) Among them, g and h indicate numbers satisfying 0 ≦ g ≦ 0.1, 0 <h ≦ 1, and ( ^{valence of M 3} ) × g + 3h = 3).
LiM ⁴ _i Mn _j O ₄ ... (4)
(In the formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In the formula (4), i and j represent numbers satisfying 0 ≦ i ≦ 0.1, 0 <j ≦ 2, and ( ^{valence of M 4} ) × i + (valence of Mn) × j = 7. .)
LiNi _k Mn _1-k O ₄ ... (5)
(In equation (5), k indicates a number satisfying 0.3 ≦ k ≦ 0.7.)
Li ₂ MnO _3- LiM ⁶ O ₂ ... (6)
In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. Indicates one or more elements selected from.)
The lithium positive electrode active material particles (B) represented by are supported, and the lithium-based solid electrolyte (C) is supported on the surface of the lithium positive electrode active material particles (B).

The lithium composite oxide secondary particles (A) constituting the positive electrode active material composite (D) for a lithium ion secondary battery of the present invention have the following formula (1) or formula (2):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (1)
(In the formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number that satisfies 0 ≦ w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3.
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (2)
(In the formula (2), 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.)
It is a secondary particle composed of lithium composite oxide particles represented by, and is a particle having a layered rock salt structure.

Lithium composite oxide particles represented by the above formula (1) (so-called Li-Ni-Co-Mn oxide, hereinafter referred to as "NCM-based composite oxide") and represented by the above formula (2). Lithium composite oxide particles (so-called Li-Ni-Co-Al oxide, hereinafter referred to as "NCA-based composite oxide") are also particles having a layered rock salt structure, and are aggregated to perform lithium composite oxidation. Form secondary particles (A). Therefore, the secondary particles are also referred to as "NCM-based composite oxide secondary particles (A)", "NCA-based composite oxide secondary particles (A)" and the like.

The NCM-based composite oxide particles represented by the above formula (1) form lithium composite oxide secondary particles (A). ^{M 1} in the formula (1) is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge.
Further, a, b, c, w in the above formula (1) 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 particles represented by the above formula (1), 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 particles represented by the formula (1) is stabilized, so that destruction of the crystal structure can be suppressed even if charging and discharging are repeated. It is considered that excellent cycle characteristics can be realized.
Specific examples of the NCM-based composite oxide particles represented by the above formula (1) 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 , LiNi _0.33 Co _0.31 Mn _0.33 Zn _0.03 O _{2 and the} like. Of these, particles composed of _{LiNi 0.8} Co _0.1 Mn _0.1 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , and LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O _{2 are preferable.}

Further, two or more kinds of NCM-based composite oxide particles represented by the above formula (1) having different compositions from each other have a core-shell structure lithium composite oxidation having a core portion (inside) and a shell portion (surface layer portion). Material 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, NCM-based composite oxide particles having a high Ni concentration that are easily eluted in the electrolytic solution are arranged in the core portion and electrolyzed. Since NCM-based composite oxide particles having a low Ni concentration can be arranged in the shell portion in contact with the liquid, it is possible to further improve the suppression of deterioration of cycle characteristics and the assurance of safety. 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) is, 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 _0.33 Co _0.33 Mn _0.34 O ₂ ), or Particles composed of (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 (1) 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 components (Ni, Mn, Co, 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. One selected from 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 _{Li PO 2} F ₂ or Two or more kinds or a composite product of these can be used.

The average particle size of the NCM-based composite oxide particles represented by the above formula (1) as primary particles is preferably 500 nm or less, more preferably 300 nm or less. By setting the average particle size of the NCM-based composite oxide particles as primary particles to at least 500 nm or less in this way, it is possible to suppress the amount of expansion and contraction of the primary particles due to the insertion and desorption of lithium ions. Particle cracking can be effectively prevented. The lower limit of the average particle size of the primary particles is not particularly limited, but is preferably 50 nm or more from the viewpoint of handling.
Here, the average particle size means the average value of the measured values of the particle size (length of the major axis) of several tens of particles in the electron microscope observation of SEM or TEM, and is synonymous with the following description. is there.

The average particle size of the NCM-based composite oxide secondary particles (A) formed by agglomeration of the primary particles is preferably 25 μm or less, more preferably 20 μm or less. When the average particle size of the secondary particles is 25 μm or less, a battery having excellent cycle characteristics can be obtained. The lower limit of the average particle size of the secondary particles is not particularly limited, but is preferably 1 μm or more, and more preferably 5 μm or more from the viewpoint of handling.
In the present specification, the NCM-based composite oxide secondary particles (A) include only the primary particles formed by forming the secondary particles, and the lithium positive electrode active material particles (B) and the lithium-based solid electrolyte (C). Does not include.

When the NCM-based composite oxide particles represented by the above formula (1) 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 25 μm, and more preferably 1 μm to 20 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 NCM-based composite oxide secondary particles (A) composed of the NCM-based composite oxide particles represented by the above formula (1) is secondary to the expansion of the NCM-based composite oxide due to the insertion of lithium ions. From the viewpoint of allowing the particles in the internal voids, 4% by volume to 12% by volume is preferable, and 5% by volume to 10% by volume is more preferable in 100% by volume of the NCM-based composite oxide secondary particles (A).
By having such an average particle size and an internal void ratio, the surface of the NCM-based composite oxide secondary particles (A) composed of the NCM-based composite oxide particles represented by the above formula (1) has an NCM-based composite oxide. The particles and the lithium positive electrode active material particles (B) are composited, and the lithium positive electrode active material particles (B) are supported so as to cover the surface of the NCM-based composite oxide secondary particles (A). Therefore, the discharge capacity and rate characteristics of the obtained lithium ion secondary battery can be sufficiently suppressed while effectively suppressing the elution of the metal components (Ni, Co, Mn, M ^{1) contained in the NCM-based composite oxide particles.} Can be enhanced to.

The NCA-based composite oxide particles represented by the above formula (2) form lithium composite oxide secondary particles (A) like the above-mentioned NCM-based composite oxide particles. ^{M 2} in the formula (2) includes 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.
Further, d, e, f, x in the above formula (2) 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 particles represented by the above formula (2) are further superior in battery capacity and output characteristics to the NCM-based composite oxide particles represented by the formula (1). 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 particles represented by the above formula (2) 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. Particles composed of O ₂ , LiNi _0.8 Co _0.15 Al _0.03 Zn _0.03 O _{2 and the} like can be mentioned. Of these, particles composed of _{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 (2) 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 components (Ni, Al, Co, 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. One selected from 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 _{Li PO 2} F ₂ or Two or more kinds or a composite product of these can be used.

The average particle size of the NCA-based composite oxide represented by the above formula (2) as the primary particles, the average particle size of the composite oxide secondary particles (A) formed by agglomeration of the primary particles, and the like. The internal void ratio of the secondary particles is the same as that of the NCM-based composite oxide particles (A) described above. That is, the average particle size of the NCA-based composite oxide particles represented by the above formula (2) as primary particles is preferably 500 nm or less, more preferably 300 nm or less, and the NCA-based composite composed of the above primary particles. The average particle size of the secondary oxide particles (A) is preferably 25 μm or less, more preferably 20 μm or less. Further, the internal void ratio of the NCA-based composite oxide secondary particles (A) composed of the NCA-based composite oxide particles represented by the above formula (2) is 4% by volume to 100% of the volume of the secondary particles. 12% by volume is preferable, and 5% by volume to 10% by volume is more preferable.
By having such an average particle size and an internal void ratio, the surface of the NCA-based composite oxide secondary particles (A) composed of the NCA-based composite oxide particles represented by the above formula (2) has an NCA-based composite oxide. Since the particles and the lithium positive electrode active material particles (B) are compounded and the lithium positive electrode active material particles (B) are supported and exist so as to cover the surface of the secondary particles, NCA-based composite oxidation While effectively suppressing the elution of metal components (Ni, Co, Al, M ² ) contained in the physical particles, the discharge capacity and rate characteristics of the obtained lithium ion secondary battery can be sufficiently enhanced.

The lithium composite oxide secondary particles (A) of the present invention are a mixture of NCM-based composite oxide particles represented by the above formula (1) and NCA-based composite oxide particles represented by the above formula (2). You may. The mixed state is that the primary particles which are NCM-based composite oxide particles represented by the above formula (1) and the primary particles which are NCA-based composite oxide particles represented by the above formula (2) coexist. The secondary particles may be formed, and also consist of only the secondary particles represented by the above formula (1) and the NCA-based composite oxide particles represented by the above formula (2) and the NCA-based composite oxide particles represented by the above formula (2). Secondary particles may be mixed, and further, primary particles which are NCM-based composite oxide particles represented by the above formula (1) and NCA-based composite oxide particles represented by the above formula (2). From the secondary particles in which the primary particles coexist, the secondary particles consisting only of the NCM-based composite oxide particles represented by the above formula (1), and the NCA-based composite oxide particles represented by the above formula (2) only. It may be a mixture of secondary particles.

NCM-based composite oxide particles and NCA-based composite oxide particles when the NCM-based composite oxide particles represented by the above formula (1) and the NCA-based composite oxide particles represented by the above formula (2) are mixed. The ratio (mass%) of the above may be appropriately adjusted according to the desired battery characteristics. For example, when the rate characteristics are emphasized, it is preferable to increase the proportion of the NCM-based composite oxide particles represented by the above formula (1). Specifically, the NCM-based composite oxide particles and the NCA-based composite oxide particles are used. The mass ratio of the composite oxide particles (NCM-based composite oxide: NCA-based composite oxide) is preferably 99.9: 0.1 to 60:40. Further, for example, when the battery capacity is emphasized, it is preferable to increase the proportion of the NCA-based composite oxide particles represented by the above formula (2), and specifically, for example, the NCM-based composite oxide particles. The mass ratio of the NCA-based composite oxide particles to the NCA-based composite oxide particles (NCM-based composite oxide: NCA-based composite oxide) is preferably 40:60 to 0.1: 99.9.

The lithium positive electrode active material particles (B) constituting the positive electrode active material composite (D) for a lithium ion secondary battery of the present invention have the following formulas (3), (4), (5), or (6). ):
LiM ³ _g Co _h O ₂・ ・ ・ (3)
(In the formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) Among them, g and h indicate numbers satisfying 0 ≦ g ≦ 0.1, 0 <h ≦ 1, and ( ^{valence of M 3} ) × g + 3h = 3).
LiM ⁴ _i Mn _j O ₄ ... (4)
(In the formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In the formula (4), i and j represent numbers satisfying 0 ≦ i ≦ 0.1, 0 <j ≦ 2, and ( ^{valence of M 4} ) × i + (valence of Mn) × j = 7. .)
LiNi _k Mn _1-k O ₄ ... (5)
(In equation (5), k indicates a number satisfying 0.3 ≦ k ≦ 0.7.)
Li ₂ MnO _3- LiM ⁶ O ₂ ... (6)
In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. Indicates one or more elements selected from.)
The lithium positive electrode active material particles (B) represented by are supported while being composited with the lithium composite oxide particles so as to cover the surface of the lithium composite oxide secondary particles (A).

The above formula (3):
LiM ³ _g Co _h O ₂・ ・ ・ (3)
(In the formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) Among them, g and h indicate numbers satisfying 0 ≦ g ≦ 0.1, 0 <h ≦ 1, and ( ^{valence of M 3} ) × g + 3h = 3).
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material having a crystal structure of a layered rock salt type structure.

The lithium cathode active material particles (B) represented by the above formula (3) are any one or more elements selected from Ni and Mn as ^{M 3 from the viewpoint of exhibiting good cycle characteristics.} It is preferable, and more preferably, 50 mol% or more ^{of M 3 is Ni.}
Specifically, LiCoO ₂ , LiMn _0.05 Co _0.95 O ₂ , LiAl _0.05 Co _0.95 O ₂ , LiMg _0.03 Co _0.98 O ₂ , and LiSi _0.03 Co _0.96 O ₂ can be used. Of these, LiCoO ₂ is preferable.

The average particle size of the lithium positive electrode active material particles (B) represented by the above formula (3) is from the viewpoint of being densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, it is preferably 100 nm to 500 nm, more preferably 100 nm to 400 nm, and further preferably 100 nm to 300 nm.

The amount of the lithium positive electrode active material particles (B) represented by the above formula (3) supported by the composite with the lithium composite oxide secondary particles (A) is the lithium composite oxide secondary particles (A). ) From the viewpoint of maximizing the performance as an active material, preferably 5% by mass to 50% by mass in 100% by mass of the total amount of the positive electrode active material composite (D) for a lithium ion secondary battery obtained by combining. It is by mass, more preferably 7% by mass to 45% by mass, and even more preferably 9% by mass to 40% by mass.

At this time, the supporting layer of the lithium positive electrode active material particles (B) formed on the surface of the lithium composite oxide secondary particles (A) by supporting the lithium positive electrode active material particles (B) represented by the formula (3). The thickness of is preferably 100 nm to 3 μm, more preferably 300 nm to 3 μm, and even more preferably 500 nm to 3 μm.

The above equation (4):
LiM ⁴ _i Mn _j O ₄ ... (4)
(In the formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In the formula (4), i and j represent numbers satisfying 0 ≦ i ≦ 0.1, 0 <j ≦ 2, and ( ^{valence of M 4} ) × i + (valence of Mn) × j = 7. .)
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material having a crystal structure of a layered rock salt type structure.

Specific examples of the lithium cathode active material particles (B) represented by the above formula (4) include LiMn ₂ O ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiCo MnO ₄ , LiCrMnO ₄ , LiFeMnO ₄ , LiAlmnO ₄ , and LiCu. _0.5 Mn _1.5 O ₄ can be used. Of these, LiMn ₂ O ₄ is preferable.

The average particle size of the lithium positive electrode active material particles (B) represented by the above formula (4) is from the viewpoint of being densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, it is preferably 100 nm to 500 nm, more preferably 100 nm to 400 nm, and further preferably 100 nm to 300 nm.

The amount of the lithium positive electrode active material particles (B) represented by the formula (4) in the positive electrode active material composite (D) for the lithium ion secondary battery and the support of the lithium positive electrode active material particles (B) formed by the support. The thickness of the layer is the same as that of the lithium positive electrode active material particles (B) represented by the above formula (3), and the carrying amount is 100, which is the total amount of the positive electrode active material composite (D) for the lithium ion secondary battery. In mass%, it is preferably 5% by mass to 50% by mass, more preferably 7% by mass to 45% by mass, still more preferably 9% by mass to 40% by mass, and the thickness of the supporting layer is It is preferably 100 nm to 3 μm, more preferably 300 nm to 3 μm, and even more preferably 500 nm to 3 μm.

The above formula (5):
LiNi _k Mn _1-k O ₄ ... (5)
(In equation (5), k indicates a number satisfying 0.3 ≦ k ≦ 0.7.)
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material having a spinel structure.

_{Specifically, LiNi 0.4} Mn _0.6 O ₄ , LiNi _0.5 Mn _0.5 O ₄ , and LiNi _0.6 Mn _0.4 O ₄ can be used as the lithium cathode active material particles (B) represented by the above formula (5). .. Of these, LiNi _0.5 Mn _0.5 O ₄ is preferable.

The average particle size of the lithium positive electrode active material particles (B) represented by the above formula (5) is from the viewpoint of being densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, it is preferably 100 nm to 500 nm, more preferably 100 nm to 400 nm, and further preferably 100 nm to 300 nm.

Supporting amount of lithium positive electrode active material particles (B) represented by the formula (5) in the positive electrode active material composite (D) for a lithium ion secondary battery and supporting of lithium positive electrode active material particles (B) formed from the supporting amount. The layer thickness is the same as that of the lithium positive electrode active material particles (B) represented by the above formulas (3) and (4), and the carrying amount is the positive electrode active material composite for a lithium ion secondary battery (a positive electrode active material composite for a lithium ion secondary battery. In 100% by mass of the total amount of D), it is preferably 5% by mass to 50% by mass, more preferably 7% by mass to 45% by mass, still more preferably 9% by mass to 40% by mass, and the supporting layer. The thickness of is preferably 100 nm to 3 μm, more preferably 300 nm to 3 μm, and even more preferably 500 nm to 3 μm.

The above formula (6):
Li ₂ MnO _3- LiM ⁶ O ₂ ... (6)
In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. Indicates one or more elements selected from.)
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material that forms a solid solution having a crystal structure of a layered rock salt type structure.

As the lithium cathode active material particles (B) represented by the above formula (6), one or more selected from Co, Ni and Mn as ^{M 6 from the viewpoint of exhibiting good cycle characteristics.} Those that are elements are preferable.
Specifically, Li ₂ MnO _3- LiNiO ₂ , Li ₂ MnO _3- LiCoO ₂ , Li ₂ MnO _3- LiMn ₂ O ₄ , Li ₂ MnO _3- LiNi _x Mn _1-x O ₂ (0 <x <1) ), Li ₂ MnO _3- LiNi _x Co _1-x O ₂ (0 <x <1), Li ₂ MnO _3- LiCo _x Mn _1-x O ₂ (0 <x <1), Li ₂ MnO _3- LiNi _1−x−y Co _x Mn _y O ₂ (0 <x <1, 0 <y <1, 0 <x + y <1) can be used. Of these, Li ₂ MnO _3- LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is preferable.

The average particle size of the lithium positive electrode active material particles (B) represented by the above formula (6) is from the viewpoint of being densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, it is preferably 50 nm to 200 nm, more preferably 50 nm to 150 nm, and further preferably 50 nm to 100 nm.

The amount of the lithium positive electrode active material particles (B) represented by the formula (6) in the positive electrode active material composite (D) for the lithium ion secondary battery is determined by the positive electrode active material composite (D) for the lithium ion secondary battery. It is preferably 5% by mass to 50% by mass, more preferably 7% by mass to 45% by mass, still more preferably 9% by mass to 40% by mass, and the thickness of the supporting layer. The size is preferably 100 nm to 3 μm, more preferably 300 nm to 3 μm, and even more preferably 500 nm to 3 μm.

The lithium positive electrode active material particles (B) represented by the above formulas (3), (4), (5), or (6) have a lithium-based solid electrolyte (C) supported on the surface thereof. ..
The content of the lithium composite oxide secondary particles (A) in the positive electrode active material composite (D) for a lithium ion secondary battery, and the total content of the lithium positive electrode active material particles (B) and the lithium-based solid electrolyte (C). The mass ratio ((A) :( B) + (C)) with and is preferably 95: 5 to 50:50, more preferably 93: 7 to 55:45, and even more preferably 91: 9. ~ 57:43.

The thickness of the supporting layer of the lithium-based solid electrolyte (C) that covers the entire surface of the lithium positive electrode active material particles (B) is preferably 1 nm to 20 nm, more preferably 5 nm to 20 nm. , More preferably 10 nm to 20 nm.
Here, the thickness of the supporting layer of the lithium-based solid electrolyte is 10 in the TEM observation regarding the cross section (cross section) of the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface. It means the average value of the measured values of the thickness of the supporting layer of the lithium-based solid electrolyte (C) on the surface of the lithium positive electrode active material particles (B), and is synonymous with the following description.

The lithium-based solid electrolyte (C) supported on the surface of the lithium positive electrode active material particles (B) has at least good lithium ion conductivity, and is formed in the firing step in the production method described later. It is a lithium-based solid electrolyte that can be used. Specifically, for example, _{any one or more of Li 3} PO _{4- Li 4} SiO ₄ and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ can be mentioned, and among them, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ). ₃ is preferred.

The average particle size of the lithium-based solid electrolyte (C) is preferably 1 nm to 10 nm, more preferably 1 nm to 8 nm, and further preferably 1 nm to 5 nm.
Here, the average particle size of the lithium-based solid electrolyte (C) is identified by the diffraction contrast on the surface portion of the lithium positive electrode active material particles (B) in the TEM observation regarding the cross section of the lithium positive electrode active material particles (B). It means the average value of the measured values of the particle sizes (length of the major axis) of several tens of lithium-based solid electrolyte particles, and is synonymous with the following description.

The average particle size of the positive electrode active material composite (D) for a lithium ion secondary battery of the present invention is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, and particularly preferably 5 μm to 15 μm. When the average particle size of the positive electrode active material composite (D) for a lithium ion secondary battery is smaller than 2 μm, the tap density is lowered and sufficient peel strength cannot be imparted to the prepared electrode, resulting in poor battery cycle characteristics. It may decrease. Further, when the average particle size is larger than 30 μm, it becomes difficult to uniformly coat the electrodes, a uniform electrode cannot be obtained, and the discharge capacity of the battery may decrease.
The tap density of the positive electrode active material composite (D) for a lithium ion secondary battery of the present invention is preferably 0.5 g / cm ^{3 to} 3.5 g / cm ³ , and more preferably 1.5 g / cm. ^{It is 3 to} 3.5 g / cm ³ . If the tap density of the positive electrode active material composite (D) for a lithium ion secondary battery ^{is smaller than 0.5 g / cm 3} , the cycle characteristics of the battery may deteriorate as described above.

The positive electrode active material composite (D) for a lithium ion secondary battery of the present invention has the following steps (I) to (III):
(I) After preparing a slurry (a-1) having a solid content concentration of 20% by mass to 65% by mass, which contains the lithium positive electrode active material particles (B) and the raw material compound of the lithium-based solid electrolyte (C), hot air is used. The granulated product (a) is spray-dried under the condition that the ratio (G / S) of the supply amount G (L / min) of the slurry (a-1) to the supply amount S (L / min) of the slurry (a-1) is 500 to 10000. The process of getting
(II) The obtained granulated product (a) is fired at 500 ° C. to 800 ° C. for 10 minutes to 3 hours, and the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface. ) To obtain a preliminary granulated product (b) having a void ratio of 45% to 80% by volume, and (III) the obtained preliminary granulated product (b) and lithium composite oxide secondary particles (A). ) Is mixed while applying compressive force and shearing force to crush the preliminary granulated product (b), and the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface. ) And the lithium composite oxide secondary particles (A) can be obtained by a step of combining the particles (A). As described above, by passing through the step (II) of obtaining the preliminary granulated product (b) composed of the lithium positive electrode active material particles (B) having a high porosity, it is easy in the subsequent step (III) without giving an excessive load. The preliminary granulated product (b) can be crushed into fine particles. As described above, the preliminary granulated product (b) composed of the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface is finely divided, and the lithium positive electrode active material particles ( B) will be separated and supplied, and the lithium positive electrode active material particles (B) on the lithium composite oxide particles will be efficiently and satisfactorily composited and supported on the surface of the lithium composite oxide secondary particles (A). It becomes possible to make it.

In the step (I) provided in the production method of the present invention, the amount of hot air supplied after preparing the slurry (a-1) containing the lithium positive electrode active material particles (B) and the raw material compound of the lithium-based solid electrolyte (C). Step of spray-drying to obtain granulated product (a) under the condition that the ratio (G / S) of G (L / min) to the supply amount S (L / min) of the slurry (a-1) is 500 to 10000. Is.

The lithium positive electrode active material particles (B) used in the step (I) are the lithium composite oxide secondary particles in the subsequent step (III) after the lithium-based solid electrolyte (C) is supported on the surface in the next step (II). The particles of the lithium positive electrode active material represented by the above formulas (3) to (6) are composited on the surface of (A), and the average particle size thereof is represented by the above formulas (3) to (5). When the lithium positive electrode active material particles (B) are used, the temperature is 100 nm to 500 nm, and when the lithium positive electrode active material particles (B) represented by the formula (6) are used, the temperature is 50 nm to 200 nm.

The content of the lithium positive electrode active material particles (B) in the slurry (a-1) is preferably 30 parts by mass to 185 parts by mass, and more preferably 50 parts by mass to 150 parts by mass with respect to 100 parts by mass of water. Is.

The raw material compound of the lithium-based solid electrolyte (C) constituting the granulated product (a) is fired in the next step (III) to produce the lithium-based solid electrolyte (C). The raw material compound to be used is preferably one that dissolves in the slurry (a-1), and water of each element constituting the lithium-based solid electrolyte (C), specifically, titanium, lithium, aluminum, silicon, boron, or phosphorus. Examples thereof include, but are not limited to, oxides, carbonates, sulfates, acetates and the like.

In carrying the lithium-based solid electrolyte (C) produced from the raw material compound by firing in the next step (III) on the surface of the lithium positive electrode active material particles (B), the lithium in the slurry (a-1). The total content of the raw material compound of the system-based solid electrolyte (C) is the total amount of the lithium positive electrode active material particles (B) obtained in the next step (III) and the lithium-based solid electrolyte (C) supported on the surface of the particles. It is desirable that the amount is 0.1% by mass to 15% by mass in 100% by mass. Specifically, for example, it is preferably 0.03 parts by mass to 35 parts by mass, and more preferably 0.05 parts by mass to 20 parts by mass with respect to 100 parts by mass of water in the slurry (a-1).
The solid content concentration in 100% by mass of the slurry (a-1) is 20% by mass to 65% by mass, preferably 30% by mass to 60% by mass, and more preferably 40% by mass to 55% by mass. %.

In preparing the slurry (a-1), a treatment using a disperser (homogenizer) is performed from the viewpoint of uniformly dispersing the raw materials of the lithium positive electrode active material particles (B) and the dissolved lithium-based solid electrolyte (C). Is preferable. Examples of such a disperser include a breaker, a beater, a low-pressure homogenizer, a high-pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short-screw extruder, a twin-screw extruder, an ultrasonic stirrer, a household juicer mixer, and the like. Can be mentioned. Of these, an ultrasonic stirrer is preferable from the viewpoint of dispersion efficiency. The degree of dispersion uniformity of the slurry (a-1) can be quantitatively evaluated by, for example, the light transmittance using a UV / visible light spectroscope or the viscosity using an E-type viscometer, or visually. It is also possible to easily evaluate by confirming that the white turbidity is uniform. The time for processing with the disperser is preferably 1 minute to 30 minutes, more preferably 2 minutes to 15 minutes.

Next, the ratio (G / S) of the obtained slurry (a-1) to the supply amount G (L / min) of hot air and the supply amount S (L / min) of the slurry (a-1) is 500 to The granulated product (a) is obtained by spray drying under the condition of 10000. The granulated product (a) is a preliminary granulated product (B) formed of lithium positive electrode active material particles (B) on which a lithium-based solid electrolyte (C) is supported on the surface by passing through the next step (II). b). In the production method of the present invention, it is possible to avoid using robust secondary particles formed by firmly aggregating the lithium positive electrode active material particles (B), and to easily crush the lithium positive electrode active material particles (B) without applying an excessive load. Since the pre-granulation product (b) is used, the lithium positive electrode active material particles (B) constituting the pre-granulation product (b) can be subjected to a lithium composite oxide without requiring an excessive shearing force or the like. It is possible to support the secondary particles (A) on the surface.

The ratio (G / S) of the supply amount G (L / min) of the hot air to the supply amount S (L / min) of the slurry (a-1) is 500 to 10000, preferably 1000 to 9000. .. The hot air temperature during spray drying is preferably 110 ° C. to 160 ° C., more preferably 120 ° C. to 140 ° C.

The particle size of the granulated product (a) obtained in the step (I) is a D ₅₀ value in the particle size distribution based on the laser diffraction / scattering method, preferably 5 μm to 25 μm, and more preferably 5 μm to 15 μm.
_{Here, the D 50} value in the particle size distribution measurement is a value obtained by a volume-based particle size distribution based on the laser diffraction / scattering method, and the D ₅₀ value means the particle size (median diameter) at a cumulative 50%. ..

In the step (II) provided in the production method of the present invention, the granulated product (a) obtained in the step (I) is calcined at 500 ° C. to 800 ° C. for 10 minutes to 3 hours to have a porosity of 45% by volume. This is a step of obtaining a preliminary granulated product (b) of ~ 80% by volume. By going through the step (II), the porosity of 45 volumes is increased while the lithium-based solid electrolyte (C) is firmly supported on the surface of the lithium positive electrode active material particles (B) constituting the preliminary granulated product (b). A pre-granulated product (b) having an appropriate crushability adjusted to% to 80% by volume can be formed.

The firing temperature is from the viewpoint of effectively producing the lithium-based solid electrolyte (C) and from the viewpoint of adjusting the porosity of the preliminary granulated product (b) to 45% by volume to 80% by volume to impart appropriate crushability. Therefore, it is 500 ° C. to 800 ° C., preferably 600 ° C. to 770 ° C., and more preferably 650 ° C. to 750 ° C. The firing time is 10 minutes to 3 hours, preferably 30 minutes to 1.5 hours.

The porosity of the pre-granulated product (b) composed of the lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is the porosity based on the mercury intrusion method, which is 45% by volume to 80% by volume. %, Preferably 50% by volume to 80% by volume.

Further, the tap density of the preliminary granulated product (b) composed of the lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is preferably 3.5 g / cm ³ or less, and more. preferably from ^{1.5g / cm 3 ~3.5g / cm 3} .

Further, the average particle size of the preliminary granulated product (b) composed of the lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is D _{50 in the particle size distribution based on the laser diffraction / scattering method.} The value is preferably 5 μm to 25 μm, and more preferably 5 μm to 15 μm.

The crushing strength of the pre-granulated product (b) composed of the lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is preferably 1.8 KN / mm or less, more preferably 1.8 KN / mm or less. It is 1.75 KN / mm or less. The crushing strength indicates the ease of crushing by compression of the preliminary granulated product (b) composed of the lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported on the surface. It means the value obtained by the formula (7).
Crushing strength (KN / mm) of pre-granulated product (b) = 10 / (t ₀ −t ₁₀ ) ・ ・ ・ (7) t ₀ in equation (7) is the surface inside a cylindrical container with a diameter of 20 mm. 3 g of a pre-granulated product (b) composed of lithium positive electrode active material particles (B) carrying a lithium-based solid electrolyte (C) was put into the mixture, and tapping by dropping from a height of 1 cm was repeated 10 times. The layer thickness (mm) of _{the pre-granulated product (b) in the filled state is shown, and t 10} is the pre-granulation when a load of 10 KN is applied to the pre-granulated product (b) in the densely packed state from above. The layer thickness (mm) of the thing (b) is shown.

In the step (III) provided in the production method of the present invention, the preliminary granulated product (b) obtained in the step (II) and the lithium composite oxide secondary particles (A) are subjected to compressive force and shearing force. Lithium positive electrode active material particles (B) and lithium composite oxide secondary particles (A) in which a lithium-based solid electrolyte (C) is supported on the surface while mixing and crushing the preliminary granulated product (b). It is a process of combining and. Through this step, the preliminary granulated product (b) was crushed on the surface of the lithium composite oxide secondary particles (A), and the lithium-based solid electrolyte (C) was supported on the surface. It is possible to obtain a positive electrode active material composite (D) for a lithium ion secondary battery in which fine lithium positive electrode active material particles (B) are supported so as to cover a dense and wide area.

In the step (III), the mixture of the lithium composite oxide secondary particles (A) and the preliminary granulated product (b) is sufficiently dry-mixed before being mixed while applying a compressive force and a shearing force. preferable. As a method of dry mixing, mixing by a normal dry mixer such as a ball mill or a V blender is preferable, and mixing by a self-revolving planetary ball mill is more preferable.

The process of mixing while applying a compressive force and a shearing force (hereinafter, also referred to as “composite”) is preferably performed in a closed container equipped with an impeller, a rotor tool, or the like. Examples of the device provided with such a closed container include a high-speed shear mill, a blade-type kneader, a high-speed mixer, and the like. Specific examples thereof include a particle design device COMPOSI, a mechanohybrid, and a high-performance flow mixer FM mixer (Japan). Coke Industries Co., Ltd.) Fine particle compounding device Mechanofusion, Nobilta (manufactured by Hosokawa Micron), surface modifier Miralo, hybridization system (manufactured by Nara Kikai Seisakusho), Erich Intensive Mixer (manufactured by Nippon Eirich) are preferably used. be able to. As the above-mentioned compounding treatment conditions, the temperature is preferably 5 ° C. to 80 ° C., more preferably 10 ° C. to 50 ° C. The atmosphere is not particularly limited, but is preferably an inert gas atmosphere or an atmospheric atmosphere.

More specifically, for example, when Nobilta (manufactured by Hosokawa Micron Co., Ltd.), which is a dry particle compounding device equipped with an impeller, is used as the compounding device, the rotation speed of the impeller is the pre-granulation product (b). ) Is efficiently crushed, and the surface of the lithium composite oxide secondary particles (A) is satisfactorily coated with the lithium positive electrode active material particles (B) having the lithium-based solid electrolyte (C) supported on the surface. From the viewpoint of obtaining the composite oxide carried in such a manner, it is preferably 2000 rpm to 6000 rpm, and more preferably 2000 rpm to 4000 rpm. The compounding time is preferably 1 minute to 10 minutes, and more preferably 1 minute to 7 minutes.
Further, when an Erich Intensive Mixer (manufactured by Nippon Eirich Co., Ltd.), which is a high-speed stirring mixer equipped with a rotor tool, is used as the device for performing such compounding, the rotation speed of the rotor tool is preferably 2000 rpm to 8000 rpm. Yes, more preferably 2000 rpm to 6000 rpm. The compounding time is preferably 1 minute to 10 minutes, and more preferably 1 minute to 7 minutes.

The compounding time and / or the rotation speed of the impeller or the like in the step (III) depends on the amount of the mixture of the lithium composite oxide secondary particles (A) and the preliminary granulated product (b) to be charged into the closed container. It is necessary to make appropriate adjustments. Then, by operating the closed container, a compressive force and a shearing force are applied to the mixture between the impeller and the like and the inner wall of the closed container, and the preliminary granulated product (b) is crushed satisfactorily while the lithium composite is used. It is possible to perform a treatment in which the secondary oxide particles (A) and the lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported on the surface are composited, and the lithium-based solid electrolyte is on the surface. The lithium ion secondary particles (B) supported by (C) are supported so as to be well composited and coated on the surface of the lithium composite oxide secondary particles (A). A positive electrode active material composite (D) for a battery can be obtained.
For example, when the compounding is performed in a closed container equipped with an impeller rotating at a rotation speed of 2000 rpm to 5000 rpm for 1 minute to 8 minutes, the amount of the mixture to be charged into the closed container is determined by the effective container (the closed container provided with the impeller). Of these, 0.1 g to 0.7 g, more preferably 0.15 g to 0.4 g, per ^{1 cm 3 of} the container corresponding to the portion capable of accommodating the mixture.

The mass of the amount of the lithium composite oxide secondary particles (A) compounded in the step (III) and the amount of the lithium positive electrode active material particles (B) having the lithium-based solid electrolyte (C) supported on the surface. The ratio (particle (A): particle (B) + particle (C)) is the content of the lithium composite oxide secondary particle (A) in the positive electrode active material composite (D) for the lithium ion secondary battery and lithium. It is the same as the mass ratio ((A): (B) + (C)) to the total content of the positive electrode active material particles (B) and the lithium-based solid electrolyte (C), and is contained in the above mixture so as to have such an amount. The amount of the preliminary granulated product (b) in the above may be adjusted.

The positive electrode active material composite for a lithium ion secondary battery of the present invention is applied as a positive electrode material, and the lithium ion secondary battery containing the positive electrode active material composite is particularly capable of having a positive electrode, a negative electrode, an electrolytic solution, and a separator as essential configurations. Not limited.

Here, as for the negative electrode, as long as lithium ions can be occluded at the time of charging and discharged 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 that is generally used as an electrolytic solution for a lithium ion secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, etc. Lactones, oxolane 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.

[Production Example 1: Production of Lithium Composite Oxide Secondary Particles (A-1)]
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. 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 A2 of a metal composite hydroxide, and then 37 g of lithium carbonate was mixed with the mixture A2 with a ball mill to obtain a powder mixture A3.
The obtained powder mixture A3 was calcined at 800 ° C. for 5 hours in an air atmosphere to be crushed and then granulated, and then calcined at 800 ° C. for 10 hours in an air atmosphere as the main firing to obtain a lithium composite oxide di. Secondary particles (A-1) (LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , average particle size 10 μm) were obtained.

[Production Example 2: Production of Lithium Composite Oxide Secondary Particles (A-2)]
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, it was mixed with a ball mill to obtain a powder mixture A4. The obtained powder mixture A4 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 to obtain lithium composite oxide secondary particles (A). -2) (LiNi _0.8 Co _0.15 Al _0.05 O ₂ , average particle size 10 μm) was obtained.

[Production Example 3: Production of particles (BC-1) in which a lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
A powder mixture of 222 g of lithium carbonate and 482 g of cobalt oxide was mixed with a ball mill so that the molar ratio of Li: Co was 1: 1 to prepare a powder mixture B1. The powder mixture B1 was compacted at a molding pressure of 500 kg / cm ³ and calcined at 700 ° C. for 5 hours in an air atmosphere. Then, this molded body was pulverized and mixed again ^{, compacted at a molding pressure of 1000 kg / cm 3} , and calcined at 900 ° C. for 10 hours in an air atmosphere to obtain _{lithium cobalt oxide (LiCoO 2).} The obtained lithium cobalt oxide was pulverized to have a particle size suitable for compounding to obtain lithium cobalt oxide particles B2 (LiCoO ₂ , average particle size 200 nm).
The resulting lithium cobalt oxide particles B2 was collected 500g _{min, LiNO 3 1.8g, Al (NO} 3) 3 · 9H 2 O 2.25g, and _{TiCl 4 6.46g, 85% H 3} PO 4 5.88g , 500 mL of water was added, and 21.86 g of 28% ammonia water was further added as a pH adjuster to obtain slurry B3 (solid content concentration 51%). The obtained slurry B3 was dispersed for 1 minute with an ultrasonic stirrer (T25, manufactured by IKA) to uniformly color the whole, and then a spray drying device (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.) was used. The mixture was spray-dried to obtain a preliminary granulated product B4.
The obtained preliminary granulated product B4 was calcined in an air atmosphere at 700 ° C. for 1 hour, and the particles (BC-) in _{which Li 1.3} Al _0.3 Ti _1.7 (PO _{4 ) 3 was supported on the surface of the lithium positive electrode active material particles.} 1) (LiCoO ₂ , average particle size: 200 nm, thickness of supporting layer of lithium-based solid electrolyte: 5 nm) was obtained.

[Production Example 4: Production of particles (BC-2) in which a lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
Production Example 3, the lithium cobalt oxide particles B2 obtained was collected 500g _{min, LiNO 3 18g, Al (NO} 3) 3 · 9H 2 O 22.5g, TiCl 4 64.6g, 85% H 3 PO 4 58 Lithium was obtained in the same manner as in Production Example 3 except that 0.8 g and 1 L of water were added, and 218.6 g of 28% ammonia water was added as a pH adjuster to obtain slurry B5 (solid content concentration 42%). Particles (BC-2) (LiCoO _{2 ) in which Li 1.3} Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of positive electrode active material particles, average particle size: 200 nm, thickness of lithium-based solid electrolyte supporting layer: 20 nm ) Was obtained.

[Production Example 5: Production of particles (BC-3) in which a lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
348 g of manganese oxide and 739 g of lithium carbonate are mixed and pulverized so that the molar ratio of Mn: Li is 2: 1. Then, lithium manganate (LiMn _{2) is fired in an air atmosphere at 800 ° C. for 12 hours.} After obtaining O ₄ ), the obtained lithium manganate was pulverized to obtain lithium manganate particles B6 (LiMn ₂ O ₄ , average particle size 200 nm).
The resulting lithium manganate particles B6 was collected 500g _{min, LiNO 3 1.8g, Al (NO} 3) 3 · 9H 2 O 2.25g, and _{TiCl 4 6.46g, 85% H 3} PO 4 5.88g , 500 mL of water was added, and 21.86 g of 28% ammonia water was further added as a pH adjuster to obtain slurry B7 (solid content concentration 51%). The obtained slurry B7 was dispersed for 1 minute with an ultrasonic stirrer (same as above) to uniformly color the whole, and then spray-dried using a spray-drying device (same as above) to prepare the pre-granulated product B8. Got
The obtained preliminary granulated product B8 was calcined in an air atmosphere at 700 ° C. for 1 hour, and the particles (BC-) in _{which Li 1.3} Al _0.3 Ti _1.7 (PO _{4 ) 3 was supported on the surface of the lithium positive electrode active material particles.} 3) (LiMn ₂ O ₄ , average particle size: 200 nm, thickness of supporting layer of lithium-based solid electrolyte: 5 nm) was obtained.

[Production Example 6: Production of particles (BC-4) in which a lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
After mixing 147.8 g of lithium carbonate, 149.4 g of nickel oxide, and 690 g of manganese carbonate with a ball mill so that the molar ratio of Li: Ni: Mn is 2: 1: 3, 900 ° C. × 24 in an air atmosphere. After firing for hours to obtain LiNi _0.5 Mn _1.5 O ₄ , it was pulverized to obtain LiNi _0.5 Mn _1.5 O ₄ particles B9 (average particle size 200 nm).
The resulting LiNi _0.5 Mn _1.5 O ₄ particles B9 was collected 500g _{min, LiNO 3 1.8g, Al (NO} 3) 3 · 9H 2 O 2.25g, TiCl 4 6.46g, 85% H 3 PO 4 5 .88 g and 500 mL of water were added, and 21.86 g of 28% ammonia water was further added as a pH adjuster to obtain slurry B10 (solid content concentration 51%). The obtained slurry B10 is dispersed for 1 minute with an ultrasonic stirrer (same as above) to uniformly color the whole, and then spray-dried using a spray-drying device (same as above) to prepare the pre-granulated product B11. Got
The obtained preliminary granulated product B11 was calcined in an air atmosphere at 700 ° C. for 1 hour, and the particles (BC-) in _{which Li 1.3} Al _0.3 Ti _1.7 (PO _{4 ) 3 was supported on the surface of the lithium positive electrode active material particles.} 4) (LiNi _0.5 Mn _1.5 O ₄ , average particle size: 200 nm, thickness of supporting layer of lithium-based solid electrolyte: 5 nm) was obtained.

[Production Example 7: Production of particles (BC-5) in which a lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
Add 1324 g of manganese acetate tetrahydrate, 323.5 g of nickel acetate tetrahydrate, 323.8 g of cobalt acetate tetrahydrate, 848 g of sodium carbonate, and 3 L of water, and stir while keeping the solution at 60 ° C. After mixing, 28% aqueous ammonia as a pH adjuster was added at a dropping rate of 300 ml / min until the pH reached 7.5 to obtain slurry B12. The obtained slurry B12 was washed with water, dried, mixed with 487.7 g of lithium carbonate, tentatively calcined at 500 ° C. for 5 hours, pulverized and mixed, and calcined at 900 ° C. for 20 hours. _{.5Li 2 MnO 3 -0.5LiMn 0.33 Co 0.33} Ni 0.33 O 2 particles B13 (average particle size: 100 nm) was obtained.
The _{0.5Li 2 MnO 3 -0.5LiMn 0.33 Co 0.33} Ni 0.33 O 2 particles B13 obtained was collected 500g _{min, LiNO 3 1.8g, Al (NO} 3) 3 · 9H 2 O 2.25g, TiCl 4 6.46 g, 85% H ₃ PO ₄ 5.88 g and 500 mL of water were added, and 21.86 g of 28% ammonia water was further added as a pH adjuster to obtain slurry B14 (solid content concentration 51%). .. The obtained slurry B14 was dispersed for 1 minute with an ultrasonic stirrer (same as above) to uniformly color the whole, and then spray-dried using a spray-drying device (same as above) to prepare the pre-granulated product B15. Got
The obtained preliminary granulated product B15 was calcined in an air atmosphere at 700 ° C. for 1 hour, and the particles (BC-) in _{which Li 1.3} Al _0.3 Ti _1.7 (PO _{4 ) 3 was supported on the surface of the lithium positive electrode active material particles. 5) (0.5Li 2 MnO 3 -0.5LiMn} 0.33 Co 0.33 Ni 0.33 O 2, average particle diameter: 100 nm, the carrier layer of lithium-based solid electrolyte thickness: 3 nm) was obtained.

[Production Example 8: Production of particles (BC-6) in which a lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
_{500 g of lithium cobalt oxide particles B2 (LiCoO 2} , average particle size 200 nm) obtained in the process of Production Example 3 is mixed with 500 mL of water, 6.22 g of lithium hydroxide monohydrate, and 4.42 g of tetraethoxysilane. Then, slurry B16 was obtained. Next, while maintaining the obtained slurry B16 at a temperature of 25 ° C., the mixture was stirred at a stirring speed of 200 rpm for 10 minutes, and then 2.44 g of 85% phosphoric acid was added dropwise and mixed with the slurry which was continuously stirred. After that, the mixture was further stirred at a stirring speed of 200 rpm for 30 minutes to obtain slurry B17 (solid content concentration 50%). The obtained slurry B17 was dispersed for 1 minute with an ultrasonic stirrer (same as above) to uniformly color the whole, and then spray-dried using a spray-drying device (same as above) to prepare the pre-granulated product B18. Got
The obtained preliminary granulated product B18 was calcined in an air atmosphere at 700 ° C. for 4 hours, and the particles (BC-6) (LiCoO) in _{which Li 3.5} Si _0.5 P _0.5 O _{4 was supported on the surface of the lithium positive electrode active material particles. 2.} Average particle size: 200 nm, thickness of supporting layer of lithium-based solid electrolyte: 5 nm) was obtained.

[Production Example 9: Production of solid electrolyte particles (S-1)]
Add 71.8 g of lithium nitrate, 90 g of aluminum nitrate hexahydrate, 516.8 g of titanium chloride, 235.2 g of phosphoric acid, and 874.2 g of 28% aqueous ammonia as a pH adjuster at 200 rpm using a planetary ball mill. After pulverizing and mixing for 2 hours, the mixture was dried to obtain a mixture B19. The obtained mixture B19 was formed into pellets, calcined in an air atmosphere at 900 ° C. for 12 hours, and then crushed in a mortar to obtain solid electrolyte particles (S-1) (Li _1.3 Al _0.3 Ti _1.7 (PO _4). ) ₃ , average particle size: 500 nm) was obtained.

[Example 1: Production of positive electrode active material complex (D-1) for lithium ion secondary battery]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1 and 200 g of the particles (BC-1) obtained in Production Example 3 were mixed with Mechanofusion (AMS-Lab, manufactured by Hosokawa Micron). The lithium cobalt oxide particles (B) were supported on the surface of the NCM-based composite oxide secondary particles (A) by performing a compounding treatment at 2600 rpm (20 m / sec) for 10 minutes. _{Lithium-based solid electrolyte Li 1.3} Al _0.3 Ti _1.7 (PO ₄ ) _{3 on} the surface of the particles (B) is a positive electrode active material composite (D-1) for lithium ion secondary batteries (average particle size 14 μm, surface). The thickness of the supporting layer of lithium cobalt oxide particles (B) supporting the lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ ^{: 2 μm and tap density 2.8 g / cm 3} ) was obtained.

[Example 2: Production of positive electrode active material complex (D-2) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A) were obtained in the same manner as in Example 1 except that 200 g of lithium positive electrode active material particles (B-1) were changed to 200 g of particles (BC-2) obtained in Production Example 4. ), And lithium cobalt oxide particles (B) are supported on the surface of the lithium cobalt oxide particles (B), and the lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the lithium ions. Lithium cobalt oxide particles (B) consisting of a positive electrode active material composite (D-2) for a secondary battery (average particle size 14 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _{3 supported on the surface).} The thickness of the supporting layer: 2 μm and the tap density of 2.6 g / cm ³ ) were obtained.

[Example 3: Production of positive electrode active material complex (D-3) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A) in the same manner as in Example 1 except that 200 g of lithium positive electrode active material particles (B-1) were changed to 200 g of particles (BC-3) obtained in Production Example 5. ) On the surface of the lithium manganate particles (B), and on the surface of the lithium manganate particles (B), the lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported. Lithium manganate particles (B) consisting of a positive electrode active material composite (D-3) for a secondary battery (average particle size 14 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _{3 supported on the surface).} The thickness of the supporting layer: 2 μm and the tap density of 2.2 g / cm ³ ) were obtained.

[Example 4: Production of positive electrode active material complex (D-4) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A) in the same manner as in Example 1 except that 200 g of lithium positive electrode active material particles (B-1) were changed to 200 g of particles (BC-4) obtained in Production Example 6. ), And LiNi _0.5 Mn _1.5 O ₄ particles (B) are supported on _{the surface of LiNi 0.5 Mn 1.5 O 4 particles (B), and Li 1.3} Al _0.3 Ti _1.7 (PO ₄ ) ₃ is a lithium-based solid electrolyte on the surface of the _{LiNi 0.5} Mn _1.5 O _{4 particles (B).} Supporting positive electrode active material composite for lithium ion secondary battery (D-4) (average particle size 14 μm, _{LiNi 0.5 supporting lithium-based solid electrolyte Li 1.3} Al _0.3 Ti _1.7 (PO ₄ ) ₃ on the surface The thickness of the supporting layer of the Mn _1.5 O ₄ particles (B): 2 μm and the tap density of 2.1 g / cm ³ ) were obtained.

[Example 5: Production of positive electrode active material complex (D-5) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A) were obtained in the same manner as in Example 1 except that 200 g of the lithium positive electrode active material particles (B-1) were changed to 200 g of the particles (BC-5) obtained in Production Example 7. 0.5Li ₂ MnO on the surface _{of) 3 -0.5LiMn 0.33 Co 0.33 Ni 0.33} O 2 particles (B) is carrying, and lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 on the surface of such particles (B) (PO ₄ ) ₃ is supported by a positive electrode active material composite (D-5) for a lithium ion secondary battery (average particle size 13 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ on the surface. the thickness of the carrying layer of the carrying 0.5Li ₂ MnO ₃ comprising -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles (B): to obtain 1.5 [mu] m, a tap density of 1.9g / cm ^3).

[Example 6: Production of positive electrode active material complex (D-6) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A) in the same manner as in Example 1 except that 300 g of lithium composite oxide secondary particles (A-1) was changed to 450 g and 200 g of particles (BC-1) was changed to 50 g. Lithium ion II in which lithium cobalt oxide particles (B) are supported on the surface of the lithium cobalt oxide particles (B) and lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _{3 is supported on the surface of the lithium cobalt oxide particles (B).} Support of lithium cobalt oxide particles (B) consisting of positive electrode active material composite (D-6) for next battery (average particle size 12 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _{3 supported on the surface)} A layer thickness: 1 μm and a tap density of 2.6 g / cm ³ ) were obtained.

[Example 7: Production of positive electrode active material complex (D-7) for lithium ion secondary battery]
Same as Example 1 except that 300 g of the lithium composite oxide secondary particles (A-1) was changed to 450 g and 200 g of the particles (BC-1) were changed to 50 g of the particles (BC-3) obtained in Production Example 5. Then, the lithium manganate particles (B) are supported on the surface of the NCM-based composite oxide secondary particles (A), and the lithium-based solid electrolyte Li _1.3 Al _0.3 Ti is supported on the surface of the lithium manganate particles (B). _1.7 (PO ₄ ) _3- supported positive electrode active material composite for lithium ion secondary battery (D-7) (average particle size 12 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _{3 on the surface} The thickness of the supporting layer of the lithium manganate particles (B) supporting the above was: 1 μm, and the tap density was 2.5 g / cm ³ ).

[Example 8: Production of positive electrode active material complex (D-8) for lithium ion secondary battery]
Same as Example 1 except that 300 g of the lithium composite oxide secondary particles (A-1) was changed to 450 g and 200 g of the particles (BC-1) were changed to 50 g of the particles (BC-4) obtained in Production Example 6. _{Then, LiNi 0.5} Mn _1.5 O ₄ particles (B) are supported on the surface of the NCM-based composite oxide secondary particles (A), and the lithium-based solid electrolyte Li _1.3 Al _{0.3 is on the surface of the particles (B).} Positive active material composite (D-8) for lithium ion secondary battery supported by Ti _1.7 (PO ₄ ) _{3 (average particle size 12 μm, lithium-based solid electrolyte Li 1.3} Al _0.3 Ti _1.7 (PO ₄ ) on the surface) ₃ comprising carrying LiNi _0.5 Mn _1.5 O ₄ of the carrier layer of the particles (B) thickness: to give 1 [mu] m, a tap density of 2.6 g / cm ^3).

[Example 9: Production of positive electrode active material complex (D-9) for lithium ion secondary battery]
Same as Example 1 except that 300 g of the lithium composite oxide secondary particles (A-1) was changed to 450 g and 200 g of the particles (BC-1) were changed to 50 g of the particles (BC-5) obtained in Production Example 7. a manner, NCM-based 0.5Li on the surface of the complex oxide secondary particle _{(a) 2 MnO 3 -0.5LiMn 0.33} Co 0.33 Ni 0.33 O 2 particles (B) is carrying, and such particles (B) Lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the positive electrode active material composite for lithium ion secondary batteries (D-9) (average particle size 11.5 μm, lithium on the surface). system solid electrolyte _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) 3 carries formed by _{0.5Li 2 MnO 3 -0.5LiMn 0.33 Co 0.33} Ni 0.33 O 2 particles bearing layer (B) thickness: 750 nm, tap A density of 2.4 g / cm ³ ) was obtained.

[Example 10: Production of positive electrode active material complex (D-10) for lithium ion secondary battery]
NCA-based in the same manner as in Example 1 except that 300 g of the lithium composite oxide secondary particles (A-1) was changed to 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2. Lithium cobalt oxide particles (B) are supported on the surface of the composite oxide secondary particles (A), and the lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) is on the surface of the lithium cobalt oxide particles (B). ₃ is carries a lithium ion secondary battery positive electrode active material complex (D-10) (average particle size 14 [mu] m, lithium on the surface based solid electrolyte _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) 3 formed by carrying The thickness of the supporting layer of the lithium cobalt oxide particles (B): 2 μm and the tap density of 2.8 g / cm ³ ) were obtained.

[Example 11: Production of positive electrode active material complex (D-11) for lithium ion secondary battery]
On the surface of the NCM-based composite oxide secondary particles (A) in the same manner as in Example 1 except that 200 g of the particles (BC-1) were changed to 200 g of the particles (BC-6) obtained in Production Example 8. A positive electrode active material for a lithium ion secondary battery in which lithium cobalt oxide particles (B) are supported and a lithium-based solid electrolyte Li _3.5 Si _0.5 P _0.5 O _{4 is supported on the surface of the lithium cobalt oxide particles (B).} Composite (D-11) (average particle size 14 μm, thickness of support layer of lithium cobalt oxide particles (B) carrying _{lithium-based solid electrolyte Li 3.5} Si _0.5 P _0.5 O _{4 on the surface: 2 μm, tap density} 2.8 g / cm ³ ) was obtained.

[Comparative Example 1: Production of Lithium Composite Particles (E-1)]
To 500 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 0.9 g of lithium nitrate, 1.13 g of aluminum nitrate hexahydrate, 3.23 g of titanium chloride, and 2.94 g of phosphoric acid were added. 500 mL of water was added, and 10.93 g of 28% ammonia water was further added as a pH adjuster to obtain slurry C1. The obtained slurry C1 was dispersed for 1 minute with an ultrasonic stirrer (T25, manufactured by IKA) to uniformly color the whole, and then a spray drying device (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.) was used. The mixture was spray-dried to obtain a preliminary granulated product C2.
The obtained preliminary granulated product C2 was calcined in an air atmosphere at 700 ° C. for 1 hour, and the surface of the lithium composite oxide secondary particles (LiNi _0.33 Co _0.33 Mn _0.34 O ₂ ) was surfaced with the lithium-based solid electrolyte Li _1.3 Al. _{Lithium composite particles (E-1) supported by 0.3} Ti _1.7 (PO ₄ ) ₃ (average particle size: 10 μm, solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ supported layer thickness: 5 nm, A tap density of 2.6 g / cm ³ ) was obtained.

[Comparative Example 2: Production of Positive Electrode Active Material Complex (E-2) for Lithium Ion Secondary Battery]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1 and 200 g of the solid electrolyte particles (S-1) obtained in Production Example 9 were used at 2600 rpm using mechanofusion (same as above). After 10 minutes of compounding treatment at (20 m / sec), lithium-based solid electrolyte particles Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ are supported on the surface of the NCM-based composite oxide secondary particles (A). A positive electrode active material composite (E-2) for a lithium ion secondary battery (average particle size 12 μm, thickness of supporting layer of lithium-based solid electrolyte particles: 1 μm, tap density 2.0 g / cm ³ ) was obtained.

[Comparative Example 3: Production of Positive Electrode Active Material Complex (E-3) for Lithium Ion Secondary Battery]
NCM-based composite oxide secondary particles in the same manner as in Example 1 except that 200 g of lithium positive electrode active material particles (B-1) were changed to 200 g of lithium cobalt oxide particles B2, which is an intermediate product of Production Example 3. Positive electrode active material composite (E-3) for lithium ion secondary battery in which lithium cobalt oxide particles are supported on the surface of (A) (average particle size 14 μm, thickness of support layer of lithium cobalt oxide particles: 2 μm, A tap density of 2.8 g / cm ³ ) was obtained.

[Comparative Example 4: Production of Positive Electrode Active Material Complex (E-4) for Lithium Ion Secondary Battery]
NCM-based composite oxide secondary particles in the same manner as in Example 1 except that 200 g of lithium positive electrode active material particles (B-1) were changed to 200 g of lithium manganate particles B5, which is an intermediate product of Production Example 5. Positive electrode active material composite (E-4) for lithium ion secondary battery in which lithium manganate particles are supported on the surface of (A) (average particle size 14 μm, thickness of support layer of lithium manganate particles: 2 μm, A tap density of 2.2 g / cm ³ ) was obtained.

[Comparative Example 5: Production of Positive Electrode Active Material Complex (E-5) for Lithium Ion Secondary Battery]
NCM-based composite oxide in the same manner as in Example 1 except that 200 g of lithium positive electrode active material particles (B-1) _{was changed to 200 g of LiNi 0.5} Mn _1.5 O _{4 particles B8, which is an intermediate product of Production Example 6.} Positive electrode active material composite (E-5) for lithium ion secondary battery in _{which LiNi 0.5} Mn _1.5 O ₄ particles are supported on the surface of the secondary particles (A) _{(average particle size 14 μm, LiNi 0.5} Mn _1.5 O ₄ particles) Thickness of the supporting layer: 2 μm, tap density 2.1 g / cm ³ ) was obtained.

[Comparative Example 6: Production of Positive Electrode Active Material Complex (E-6) for Lithium Ion Secondary Battery]
Lithium positive electrode active material particles (B-1) 200g, except that the _{0.5Li 2 MnO 3 -0.5LiMn 0.33 Co 0.33} Ni 0.33 O 2 particles B12 which is an intermediate product of Preparation 7 was changed to 200 g, Example 1 in the same manner as, NCM-based composite oxide secondary particle (a) 0.5Li ₂ MnO ₃ on the surface of the -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ lithium ion secondary particles are formed by carrying battery positive electrode active material complex (E-6) (average particle size _{13μm, 0.5Li 2 MnO 3 -0.5LiMn 0.33} Co 0.33 Ni 0.33 O 2 particles bearing layer thickness: 1.5 [mu] m, a tap density of 1.9 g / cm ³ ) was obtained.

[Comparative Example 7: Production of Positive Electrode Active Material Complex (E-7) for Lithium Ion Secondary Battery]
300 g of lithium composite oxide secondary particles (A-1), 300 g of lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and 200 g of lithium positive electrode active material particles (B-1) were added. Lithium cobalt oxide particles were supported on the surface of the NCA-based composite oxide secondary particles (A) in the same manner as in Example 1 except that the lithium cobalt oxide particles B2, which was an intermediate product of Production Example 3, was changed to 200 g. A positive electrode active material composite (E-7) for a lithium ion secondary battery (average particle size 14 μm, thickness of supporting layer of lithium cobalt oxide particles: 2 μm, tap density 2.8 g / cm ³ ) was obtained.

[Comparative Example 8: Production of Positive Electrode Active Material Complex (E-8) for Lithium Ion Secondary Battery]
NCM-based composite oxide secondary particles (A-1) were changed to 490 g and 200 g of lithium positive electrode active material particles (B-1) were changed to 10 g in the same manner as in Example 1. Lithium cobalt oxide particles (B) are supported on the surface of the particles (A), and the lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the lithium cobalt oxide particles (B). Lithium-ion secondary battery positive electrode active material composite (E-8) (average particle size 10.5 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ supported on the surface) Lithium cobalt oxide The thickness of the supporting layer of the particles (B): 200 nm and the tap density of 2.6 g / cm ³ ) were obtained.

[Comparative Example 9: Production of Positive Electrode Active Material Complex (E-9) for Lithium Ion Secondary Battery]
NCM-based composite oxide secondary particles were changed to 200 g of lithium composite oxide secondary particles (A-1) and 200 g of lithium positive electrode active material particles (B-1) in the same manner as in Example 1. Lithium cobalt oxide particles (B) are supported on the surface of the particles (A), and the lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the lithium cobalt oxide particles (B). Lithium ion secondary battery positive electrode active material composite (E-9) (average particle size 18 μm, lithium cobalt oxide particles ( _{PO 4} ) _{3 supporting the lithium-based solid electrolyte Li 1.3} Al _0.3 Ti _1.7 (PO 4) 3 on the surface. The thickness of the supporting layer of B): 4 μm and the tap density of 2.8 g / cm ³ ) were obtained.

<< Evaluation of discharge capacity and rate characteristics >>
All the positive electrode active material composites for lithium ion secondary batteries obtained in Examples 1 to 11 and Comparative Examples 1 to 9 were used as positive electrode materials to prepare positive electrodes for lithium ion secondary batteries. Specifically, each of the obtained positive electrode active material composites for lithium ion secondary batteries, Ketjen black, and polyvinylidene fluoride were mixed at a mass ratio of 90: 5: 5, and N-methyl-2 was mixed thereto. -Pyrrolidone was added and kneaded thoroughly to prepare a positive electrode slurry. The positive electrode slurry was applied to a current collector made of aluminum foil having a thickness of 20 μm using a coating machine, 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 positive electrode. For the negative electrode, a lithium foil punched to φ15 mm was used. _{As the electrolytic solution, one in which LiPF 6} 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. A polymer porous film was used as the separator. 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).
A charge / discharge test was performed using the obtained secondary battery. Specifically, after constant current charging with a current of 34 mA / g and a voltage of 4.25 V, a constant current discharge with a current of 34 mA / g and a final voltage of 3.0 V is applied, and the discharge capacity at a current density of 34 mA / g (0.2 C) is set. I asked. Further, constant current charging was performed under the same conditions to obtain constant current discharge with a current density of 510 mA / g and a final voltage of 3.0 V, and the discharge capacity at a current density of 510 mA / g (3C) was determined. All charge / discharge tests were performed at 30 ° C. The results are shown in Table 1.
Further, from the obtained discharge capacity, the discharge capacity ratio (%) was calculated by the following formula (8). The results are shown in Table 1.
Discharge capacity ratio (%) = (Discharge capacity at 3C) /
(Discharge capacity at 0.2C) x 100 ... (8)

<< Measurement of adsorbed water content >>
All the positive electrode active material composites for lithium ion secondary batteries obtained in Examples 1 to 11 and Comparative Examples 1 to 9 are allowed to stand in an environment at a temperature of 20 ° C. and a relative humidity of 50% for 1 day to reach equilibrium. After adsorbing water to a temperature of 150 ° C. and holding it for 20 minutes, the temperature was further raised to 250 ° C. and held for 20 minutes, starting from the time when the temperature was raised to 250 ° C. and held for 20 minutes. The amount of water volatilized during the end point when the constant temperature state at ° C. was completed was measured with a Karl Fischer titer (MKC-610, manufactured by Kyoto Electronics Industry Co., Ltd.). The measurement results are shown in Table 1.

From the results in Table 1, it can be seen that all the examples have good discharge capacity and rate characteristics (discharge capacity ratio), and the amount of water adsorbed by the positive electrode active material complex is effectively reduced.
On the other hand, in the comparative example, it can be seen that at least one of the discharge capacity and the rate characteristic is inferior to that of the embodiment. In addition, the amount of water adsorbed on the positive electrode active material complex is inferior to that of the examples in most cases.
From the above, it can be seen that the positive electrode active material composite for a lithium ion secondary battery of the present invention is excellent in discharge capacity and rate characteristics. Further, since the amount of water adsorbed is also reduced, the positive electrode active material composite for a lithium ion secondary battery of the present invention has good performance in terms of durability-related characteristics such as cycle characteristics. I understand.

Claims (7)

The following formula (1) or formula (2):
LiNi _a Co _b Mn _c M ¹ _w O ₂ ... (1)
(In the formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge. A, b, c, w are 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number that satisfies 0 ≦ w ≦ 0.3 and 3a + 3b + 3c + ( ^{valence of M 1} ) × w = 3.
^{_{LiNi d Co e Al f M 2}} x O 2 ··· (2)
(In the formula (2), 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.)
On the surface of the lithium composite oxide secondary particles (A) composed of lithium composite oxide particles represented by, the following formula (3), formula (4), formula (5), or formula (6):
LiM ³ _g Co _h O ₂・ ・ ・ (3)
(In the formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) Among them, g and h indicate numbers satisfying 0 ≦ g ≦ 0.1, 0 <h ≦ 1, and ( ^{valence of M 3} ) × g + 3h = 3).
LiM ⁴ _i Mn _j O ₄ ... (4)
(In the formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In the formula (4), i and j represent numbers satisfying 0 ≦ i ≦ 0.1, 0 <j ≦ 2, and ( ^{valence of M 4} ) × i + (valence of Mn) × j = 7. .)
LiNi _k Mn _1-k O ₄ ... (5)
(In equation (5), k indicates a number satisfying 0.3 ≦ k ≦ 0.7.)
Li ₂ MnO _3- LiM ⁶ O ₂ ... (6)
In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. Indicates one or more elements selected from.)
The positive electrode activity for a lithium ion secondary battery is supported by the lithium positive electrode active material particles (B) represented by, and the lithium-based solid electrolyte (C) is supported on the surface of the lithium positive electrode active material particles (B). Material complex. Mass ratio of the content of the lithium composite oxide secondary particles (A) to the total content of the lithium positive electrode active material particles (B) and the lithium-based solid electrolyte (C) ((A): (B) + (C) )) Is the positive electrode active material composite for a lithium ion secondary battery according to claim 1, wherein the ratio is 95: 5 to 50:50. The mass ratio ((B): (C)) of the content of the lithium positive electrode active material particles (B) to the content of the lithium-based solid electrolyte (C) is 99.5: 0.5 to 85:15. The positive electrode active material composite for a lithium ion secondary battery according to claim 1 or 2. The invention according to any one of claims 1 to 3, wherein the lithium-based solid electrolyte (C) is at least one of Li ₃ PO _{4- Li 4} SiO ₄ and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _3. Positive electrode active material composite for lithium-ion secondary batteries. The positive electrode active material composite for a lithium ion secondary battery according to any one of claims 1 to 4, wherein the average particle size is 2 μm to 30 μm. Next step (I) to step (III):
(I) After preparing a slurry (a-1) having a solid content concentration of 20% by mass to 65% by mass, which contains the lithium positive electrode active material particles (B) and the raw material compound of the lithium-based solid electrolyte (C), hot air is used. The granulated product (a) is spray-dried under the condition that the ratio (G / S) of the supply amount G (L / min) of the slurry (a-1) to the supply amount S (L / min) of the slurry (a-1) is 500 to 10000. The process of getting
(II) The obtained granulated product (a) is fired at 500 ° C. to 800 ° C. for 10 minutes to 3 hours, and the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface. ) To obtain a preliminary granulated product (b) having a void ratio of 45% to 80% by volume, and (III) the obtained preliminary granulated product (b) and lithium composite oxide secondary particles (A). ) Is mixed while applying compressive force and shearing force to crush the preliminary granulated product (b), and the lithium positive electrode active material particles (B) in which the lithium-based solid electrolyte (C) is supported on the surface. The method for producing a positive electrode active material composite for a lithium ion secondary battery according to any one of claims 1 to 5, further comprising a step of combining the secondary particles (A) with the lithium composite oxide secondary particles (A). The method for producing a positive electrode active material composite for a lithium ion secondary battery according to claim 6, wherein the granulated product (a) obtained in the step (I) has a particle size of 5 μm to 25 μm.