JP7165608B2 - Positive electrode active material composite for lithium ion secondary battery and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a positive electrode active material composite for lithium ion secondary batteries capable of effectively reducing the amount of water absorbed, and a method for producing the same.

Lithium composite oxides are used as positive electrode active materials that can constitute high-power and high-capacity lithium-ion secondary batteries. In addition, the capacity of the battery decreases as the charge/discharge cycles are repeated, and especially when used for a long period of time, the capacity of the battery may decrease significantly. The reason for this is thought to be that the crystal structure of the lithium composite oxide is likely to collapse due to elution of the transition metal component into the electrolytic solution during charging. Further, when the crystal structure of the lithium composite oxide is collapsed, the transition metal component of the lithium composite oxide is eluted into the surrounding electrolyte, 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, Patent Document 1 discloses a positive electrode active material in which a coating layer, which is a mixture of lithium-based polyanion particles and a carbon material, is formed on at least part of the surface of lithium composite oxide particles. Attempts have been made to improve the high-temperature characteristics of In addition, Patent Document 2 discloses a positive electrode active material that is mechanically milled so that lithium-based polyanion particles are partially in contact with the surface of a lithium composite oxide. I am planning. Furthermore, in Patent Document 3, lithium-based polyanion particles having a carbon coating layer with good conductivity on the surface are coated on a lithium composite oxide to obtain a positive electrode active material that can improve cycle characteristics and storage characteristics.

JP 2004-319129 A JP 2007-335245 A Japanese Patent Application Laid-Open No. 2008-210701

However, the present inventors' studies have revealed that even with the technique described in the above patent document, the discharge capacity of the secondary battery is still insufficient when it is formed. Further studies by the present inventors revealed that, since it is difficult to cover the entire surface of the lithium-based polyanion particles with the carbon material alone, the surfaces of the lithium-based polyanion particles are exposed without being covered with the carbon material. It was found that the moisture in the atmosphere deteriorates the quality of the battery, and this is a major factor in deteriorating the battery characteristics.

Therefore, an object of the present invention is to realize a lithium ion secondary battery that exhibits stable battery characteristics by imparting properties that make it difficult to adsorb moisture while allowing lithium-based polyanion particles to exist on the surface of lithium composite oxide particles. An object of the present invention is to provide a positive electrode active material composite for a lithium ion secondary battery that can

Therefore, the present inventors have made intensive studies to solve the above problems, and as a result, specific lithium-based polyanion particles (B) are supported on the surface of specific lithium composite oxide secondary particles (A). If a positive electrode active material composite for a lithium ion secondary battery in which a lithium-based solid electrolyte and carbon are also supported on the surface of the lithium-based polyanion particles (B), the amount of water adsorption can be effectively reduced and obtained. It has been found that it becomes possible to effectively improve the battery physical properties of a lithium ion secondary battery that can be used.

Therefore, the present invention provides the following formula (1) or (2):
_{LiNiaCobMncM1wO2 (} ¹ _{) _ _}
(In 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, one or more elements selected from Bi and Ge, where a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, 0≦w≦0.3 and 3a+3b+3c+(valence of M1)×w= ³ .)
_{LiNidCoeAlfM2xO2 (} ² _{) _ _}
(In formula ( ² ), M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and one or more elements selected from Ge, d, e, f, and x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ A number that satisfies ^x≤0.3 and 3d+3e+3f+(valence of M2)×x=3.)
On the surface of the lithium composite oxide secondary particles (A) made of lithium composite oxide particles represented by the following formula (3) or (4):
_{LigMnhFeiM3yPO4 (} ³ _{) _ _}
(In formula ( ³ ), M3 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. g, h, i, and y are 0 < g ≤ 1.2, 0.3 ≤ h ≤ 1, 0 ≤ i ≤ 0.7, and 0 ≤ y ≤ 0.3, and g + (valence of Mn) × h + (valence of Fe ) x i + (valence of M3) x y = ^3. )
_{LijMnkFe1M4zSiO4 (} ⁴ _{) _ _}
(In formula ( ⁴ ), M4 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. j, k, l and z satisfy 0 < j ≤ 2.4, 0 ≤ k ≤ 1.2, 0 ≤ l ≤ 1.2, 0 ≤ z ≤ 1.2, and k + l ≠ 0, and j + (Mn valence) x k + (valence of Fe) x l + (valence of M4) x z = ^4. )
The lithium-based polyanion particles (B) represented by are supported, and the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface of the lithium-based polyanion particles (B),
The mass ratio ((D):(C)) of the supported amount of the lithium-based solid electrolyte (D) and the supported amount of carbon (C) on the surfaces of the lithium-based polyanion particles (B) is 1:5 to 7:1. The present invention provides a positive electrode active material composite for a lithium ion secondary battery.

The present invention also provides the following steps (I) to (IV):
The following steps (I)-(IV):
(I) a step of preparing a slurry containing a lithium compound, a metal compound containing at least an iron compound or a manganese compound, a phosphoric acid compound or a silicate compound, and then subjecting it to a hydrothermal reaction to obtain lithium-based polyanion primary particles;
(II) After preparing a slurry having a solid content concentration of 10% by mass to 35% by mass containing the obtained lithium-based polyanion primary particles and the raw material compound of the lithium-based solid electrolyte (D), the hot air supply amount G ( L/min) to the slurry (b-5) supply amount S (L/min) ratio (G/S) of 500 to 10000 to obtain granules by spray drying;
(III) A step of calcining the obtained granules at 500° C. to 800° C. for 10 minutes to 3 hours to obtain a pre-granulated product (b) having a porosity of 45% to 80% by volume, and ( IV) The obtained preliminary granules (b) and the lithium composite oxide secondary particles (A) are mixed while applying a compressive force and a shearing force to disintegrate the preliminary granules (b), A step of supporting the lithium-based solid electrolyte (D) and carbon (C) on the surface of the lithium-based polyanion particles (B) and compounding the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). with
Either the slurry prepared in step (I) or the slurry prepared in step (II) is a slurry to which a carbon source (C') is further added, or A water-insoluble carbon material (C4) is added together with the particles (b) and the lithium composite oxide secondary particles (A), and the positive electrode active material for a lithium ion secondary battery is mixed while applying compressive force and shear force. A method for manufacturing a composite is provided.

According to the positive electrode active material composite for a lithium ion secondary battery of the present invention, the lithium-based solid electrolyte and carbon are effectively supported on the particle surface while complementing each other, so that the property of being difficult to adsorb moisture is imparted. Therefore, it is possible to satisfactorily combine the characteristics of both lithium composite oxide particles with high energy density and lithium-based polyanion particles with excellent structural stability.
Therefore, by applying such a positive electrode active material composite for a lithium ion secondary battery as a positive electrode material, it is possible to realize a lithium ion secondary battery exhibiting excellent battery characteristics.

The present invention will be described in detail below.
The positive electrode active material composite for lithium ion secondary batteries of the present invention has the following formula (1) or (2):
_{LiNiaCobMncM1wO2 (} ¹ _{) _ _}
(In 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, one or more elements selected from Bi and Ge, where a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, 0≦w≦0.3 and 3a+3b+3c+(valence of M1)×w= ³ .)
_{LiNidCoeAlfM2xO2 (} ² _{) _ _}
(In formula ( ² ), M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and one or more elements selected from Ge, d, e, f, and x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ A number that satisfies ^x≤0.3 and 3d+3e+3f+(valence of M2)×x=3.)
On the surface of the lithium composite oxide secondary particles (A) made of lithium composite oxide particles represented by the following formula (3) or (4):
_{LigMnhFeiM3yPO4 (} ³ _{) _ _}
(In formula ( ³ ), M3 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. g, h, i, and y are 0 < g ≤ 1.2, 0.3 ≤ h ≤ 1, 0 ≤ i ≤ 0.7, and 0 ≤ y ≤ 0.3, and g + (valence of Mn) × h + (valence of Fe ) x i + (valence of M3) x y = ^3. )
_{LijMnkFe1M4zSiO4 (} ⁴ _{) _ _}
(In formula ( ⁴ ), M4 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. j, k, l and z satisfy 0 < j ≤ 2.4, 0 ≤ k ≤ 1.2, 0 ≤ l ≤ 1.2, 0 ≤ z ≤ 1.2, and k + l ≠ 0, and j + (Mn valence) x k + (valence of Fe) x l + (valence of M4) x z = ^4. )
The lithium-based polyanion particles (B) represented by are supported, and the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface of the lithium-based polyanion particles (B),
The mass ratio ((D):(C)) of the supported amount of the lithium-based solid electrolyte (D) and the supported amount of carbon (C) on the surfaces of the lithium-based polyanion particles (B) is 1:5 to 7:1. is.

The lithium composite oxide secondary particles (A) constituting the positive electrode active material composite for lithium ion secondary batteries of the present invention are represented by the following formula (1) or (2):
_{LiNiaCobMncM1wO2 (} ¹ _{) _ _}
(In 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, one or more elements selected from Bi and Ge, where a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, 0≦w≦0.3 and 3a+3b+3c+(valence of M1)×w= ³ .)
_{LiNidCoeAlfM2xO2 (} ² _{) _ _}
(In formula ( ² ), M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and one or more elements selected from Ge, d, e, f, and x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ A number that satisfies ^x≤0.3 and 3d+3e+3f+(valence of M2)×x=3.)
It is a secondary particle made of lithium composite oxide particles represented by and has 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 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 composite oxide”) are also particles having a layered rock salt structure, and by agglomeration, lithium composite oxide Secondary particles (A) are formed. Therefore, the secondary particles are similarly 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 formula (1) is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, It represents one or more elements selected from Bi and Ge.
Further, a, b, c, and w in the above formula (1) are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, 0≦w≦0.3, It is also a number that satisfies 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. Moreover, from the viewpoint of cycle characteristics, it is preferable that a part of the transition element is replaced with another metal element M ¹ . Substitution with these metal elements M stabilizes the crystal structure of the NCM-based composite oxide particles represented by formula ( ¹ ). It is believed that excellent cycle characteristics can be achieved.
Specific examples of the NCM-based composite oxide particles represented by the 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 , LiNi0.2Co0.4Mn0.4O2 , LiNi0.33Co0.31Mn0.33Mg0.03O2 , or LiNi0.33Co0.31Mn0.33Zn0.03O2 . _ _ _ _ _ _} Among them, when the discharge capacity is emphasized, particles having a composition with a large amount of Ni such as LiNi _0.8 Co _0.1 Mn _0.1 O ₂ and LiNi _0.6 Co _0.2 Mn _0.2 O ₂ are preferable. Particles having a composition with a small amount of Ni such as 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.

Furthermore, two or more NCM-based composite oxide particles having different compositions from each other and represented by the above formula (1) are a core-shell structure having a core portion (inside) and a shell portion (surface layer portion). Lithium composite oxide Secondary particles (A) (NCM-based composite oxide secondary particles (A)) may be formed.

By forming the NCM-based composite oxide secondary particles (A) formed by forming this core-shell structure, NCM-based composite oxide particles with a high Ni concentration that are easily eluted in the electrolytic solution are arranged in the core portion, and electrolysis Since the NCM-based composite oxide particles having a low Ni concentration can be arranged in the shell portion that comes into contact with the liquid, it is possible to further improve the suppression of deterioration in cycle characteristics and the assurance of safety. At this time, the core portion may be composed of one phase, or may be composed of two or more phases having different compositions. As a mode in which the core portion is composed of two or more phases, a structure in which a plurality of phases are concentrically layered and laminated, or a structure in which the composition changes transitionally from the surface of the core portion toward the center portion may be used. good.
Further, the shell portion may be formed outside the core portion, and may be composed of one phase like the core portion, or may be composed of two or more phases having different compositions.

Specifically, the NCM-based composite oxide secondary particles (A) formed by forming a core-shell structure with two or more NCM-based composite oxide particles having different compositions include (core part) - (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 such as (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 ) can be used.

Furthermore, the NCM-based composite oxide particles represented by formula (1) above may be coated with a metal oxide, metal fluoride or 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 to the electrolytic solution can suppress the elution of Such coatings include _CeO2 , _SiO2 , MgO, _{Al2O3 ,} ZrO2, _TiO2 , ZnO, _RuO2 , _SnO2 , _CoO , _Nb2O5 , _CuO , _V2O5 , _{MoO3 , one selected} from _La2O3 , _WO3 , _AlF3 , _{NiF2 , MgF2} , _{Li3PO4 , Li4P2O7} , _{LiPO3 , Li2PO3F} , and _{LiPO2F2 ,} or Two or more kinds, or a composite thereof can be used.

The average particle size of the primary particles of the NCM-based composite oxide particles represented by the formula (1) is preferably 500 nm or less, more preferably 300 nm or less. Thus, by setting the average particle diameter of the NCM-based composite oxide particles as primary particles to at least 500 nm or less, the amount of expansion and contraction of the primary particles due to the insertion and extraction of lithium ions can be suppressed, Grain cracking can be effectively prevented. Although the lower limit of the average particle diameter of the primary particles is not particularly limited, it 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 (major axis length) of several tens of particles in SEM or TEM electron microscope observation, and is synonymous in the following description. be.

The average particle size of the NCM-based composite oxide secondary particles (A) formed by aggregation of the primary particles is preferably 25 μm or less, more preferably 20 μm or less. When the secondary particles have an average particle size of 25 μm or less, a battery with excellent cycle characteristics can be obtained. Although the lower limit of the average particle diameter of the secondary particles is not particularly limited, it is preferably 1 μm or more, more preferably 5 μm or more, from the viewpoint of handling.
In this specification, the NCM-based composite oxide secondary particles (A) include only primary particles forming secondary particles, and do not include lithium-based polyanion particles (B) or carbon (C).

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 The particle size is preferably between 50 nm and 500 nm, more preferably between 50 nm and 300 nm. The average particle size of the core formed by aggregation of the primary particles is preferably 1 μm to 25 μm, more preferably 1 μm to 20 μm.
In addition, the average particle size of the NCM-based composite oxide particles constituting the shell portion covering the surface of the core portion is preferably 50 nm to 500 nm, more preferably 50 nm to 300 nm, and The layer thickness of the shell portion formed by aggregation of the primary particles is preferably 0.1 μm to 5 μm, more preferably 0.1 μm to 2.5 μm.

The internal porosity 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 accompanying the insertion of lithium ions. From the viewpoint of allowing it in the internal voids of the particles, it is preferably 4% by volume to 12% by volume, more preferably 5% by volume to 10% by volume, based on 100% by volume of the NCM composite oxide secondary particles (A).
By having such an average particle size and internal porosity, on 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), the NCM-based composite oxide The particles and the lithium-based polyanion particles (B) are composited, and the lithium-based polyanion particles (B) are supported so as to cover the surfaces of the NCM-based composite oxide secondary particles (A). Therefore, it is possible to effectively suppress the elution of the metal components (Ni, Co, Mn, M ¹ ) contained in the NCM-based composite oxide particles.

The NCA-based composite oxide particles represented by the above formula (2) form lithium composite oxide secondary particles (A), like the NCM-based composite oxide particles. M ² in formula (2) is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and It represents one or more elements selected from Ge.
Further, d, e, f, and x in the above formula (2) are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦x≦0.3, It is also a number that satisfies 3d+3e+3f+(valence of M ² )×x=3.

The NCA-based composite oxide particles represented by formula (2) above are superior to the NCM-based composite oxide particles represented by formula (1) in battery capacity and output characteristics. In addition, due to the inclusion of Al, deterioration due to moisture in the atmosphere is unlikely to occur, and safety is also excellent.
Specific examples of the NCA-based composite oxide particles represented by the 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 of O ₂ , LiNi _0.8 Co _0.15 Al _0.03 Zn _0.03 O ₂ and the like can be mentioned. Among them, particles made of LiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ are preferable.

Furthermore, the NCA-based composite oxide particles represented by the above formula (2) may be coated with a metal oxide, metal fluoride or metal phosphate. By coating the NCA-based composite oxide particles with these metal oxides, metal fluorides or metal phosphates, metal components (Ni, Al, Co, M ² ) from the NCA-based composite oxide particles to the electrolytic solution can suppress the elution of Such coatings include _CeO2 , _SiO2 , MgO, _{Al2O3 ,} ZrO2, _TiO2 , ZnO, _RuO2 , _SnO2 , _CoO , _Nb2O5 , _CuO , _V2O5 , _{MoO3 , one selected} from _La2O3 , _WO3 , _AlF3 , _{NiF2 , MgF2} , _{Li3PO4 , Li4P2O7} , _{LiPO3 , Li2PO3F} , and _{LiPO2F2 ,} or Two or more kinds, or a composite thereof can be used.

The average particle size of the NCA-based composite oxide primary particles represented by the above formula (2), the average particle size of the composite oxide secondary particles (A) formed by agglomeration of the primary particles, and such The internal porosity of the secondary particles is the same as that of the NCM-based composite oxide particles (A). That is, the average particle diameter 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 oxide particles composed of the primary particles The average particle diameter of the oxide secondary particles (A) is preferably 25 μm or less, more preferably 20 μm or less. In addition, the internal porosity of the NCA-based composite oxide secondary particles (A) made of the NCA-based composite oxide particles represented by the above formula (2) is 4% by volume or more in 100% of the volume of the secondary particles. 12% by volume is preferred, and 5% to 10% by volume is more preferred.
By having such an average particle size and internal porosity, on 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), the NCA-based composite oxide Since the particles and the lithium-based polyanion particles (B) are composited and the lithium-based polyanion particles (B) are supported so as to cover the surfaces of the secondary particles, the NCA-based composite oxide particles elution of metal components (Ni, Co, Al, M ² ) contained in the can be effectively suppressed.

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). may The mixed state is the primary particles that are the NCM-based composite oxide particles represented by the above formula (1) and the primary particles that are the NCA-based composite oxide particles represented by the above formula (2). Secondary particles may be formed, and secondary particles consisting of only the NCM-based composite oxide particles represented by the above formula (1) and consisting only of the NCA-based composite oxide particles represented by the above formula (2) Secondary particles may be mixed, and furthermore, the primary particles are the NCM-based composite oxide particles represented by the above formula (1) and the NCA-based composite oxide particles are represented by the above formula (2). Secondary particles coexisting with primary particles, secondary particles consisting only of NCM-based composite oxide particles represented by the above formula (1), and only NCA-based composite oxide particles represented by the above formula (2) Secondary particles may be mixed. In the case where the secondary particles are composed of only the NCA-based mixed oxide particles represented by the above formula (1), two or more NCA-based mixed oxide particles having different compositions form a core-shell structure. It may be anything else.

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. (% by mass) may be adjusted as appropriate depending on the desired battery characteristics. For example, when the rate characteristics are emphasized, it is preferable to increase the ratio of the NCM-based composite oxide particles represented by the above formula (1). The mass ratio of the composite oxide particles (NCM composite oxide:NCA composite oxide) is preferably 99.9:0.1 to 60:40. Further, for example, when the battery capacity is important, it is preferable to increase the ratio of the NCA-based composite oxide particles represented by the above formula (2). Specifically, for example, the NCM-based composite oxide particles and 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-based polyanion particles (B) constituting the positive electrode active material composite for lithium ion secondary batteries of the present invention are represented by the following formula (3) or (4):
_{LigMnhFeiM3yPO4 (} ³ _{) _ _}
(In formula ( ³ ), M3 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. g, h, i, and y are 0 < g ≤ 1.2, 0.3 ≤ h ≤ 1, 0 ≤ i ≤ 0.7, and 0 ≤ y ≤ 0.3, and g + (valence of Mn) × h + (valence of Fe ) x i + (valence of M3) x y = ^3. )
_{LijMnkFe1M4zSiO4 (} ⁴ _{) _ _}
(In formula ( ⁴ ), M4 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. j, k, l and z satisfy 0 < j ≤ 2.4, 0 ≤ k ≤ 1.2, 0 ≤ l ≤ 1.2, 0 ≤ z ≤ 1.2, and k + l ≠ 0, and j + (Mn valence) x k + (valence of Fe) x l + (valence of M4) x z = ^4. )
A particle having an olivine-type structure represented by and on the surface thereof, a lithium-based solid electrolyte (D) and carbon (C) at a mass ratio of 1:5 to 7:1 ((D):(C)) is supported in an amount of Further, the lithium-based polyanion particles (B) are supported while being compounded with the lithium composite oxide particles so as to favorably coat the surfaces of the lithium composite oxide secondary particles (A).

The lithium-based polyanion particles (B) represented by the above formula (3) are preferably 0.5 ≤ g ≤ 1.2 from the viewpoint of the average discharge voltage of the positive electrode active material composite for lithium ion secondary batteries, 0.6≦g≦1.1 is more preferred, and 0.65≦g≦1.05 is even more preferred. _{Specifically , LiMnPO4 , LiMn0.9Fe0.1PO4 , LiMn0.8Fe0.2PO4 , LiMn0.75Fe0.15Mg0.1PO4 , LiMn0.75Fe0.19Zr0.03PO4 , LiMn0.7Fe0.6Fe0.3PO4 , LiMn0.3PO4 _ _ _ _ Fe0.4PO4 , LiMn0.5Fe0.5PO4 , Li1.2Mn0.63Fe0.27PO4 , Li0.6Mn0.84Fe0.36PO4 and the like , especially LiMn0.8Fe0.2PO4 , Li1.2Mn0.63Fe0.27FePO4 _ _ _ _ 4} or Li _0.6 Mn _0.84 Fe _0.36 PO ₄ are preferred.
Further, specific examples of the lithium-based polyanion particles (B) represented by the above formula (4) include Li ₂ Mn _0.45 Fe _0.45 Co _0.1 SiO ₄ , Li ₂ Mn _0.54 Fe _0.36 Al _0.066 SiO ₄ , Li ₂ Ｍｎ _0.45 Ｆｅ _0.45 Ｚｎ _0.1 ＳｉＯ ₄ 、Ｌｉ ₂ Ｍｎ _0.54 Ｆｅ _0.36 Ｖ _0.066 ＳｉＯ ₄ 、Ｌｉ ₂ Ｍｎ _0.658 Ｆｅ _0.282 Ｚｒ _0.02 ＳｉＯ ₄ 、Ｌｉ _2.2 Ｍｎ _0.594 Ｆｅ _0.252 Ｚｒ _0.027 ＳｉＯ ₄ 、Ｌｉ _1.2 Ｍｎ _0.294 Ｆｅ _0.392 Ｚｒ _0.042 SiO ₄ and the like, among which Li ₂ Mn _0.658 Fe _0.282 Zr _0.02 SiO ₄ , Li _2.2 Mn _0.594 Fe _0.252 Zr _0.027 SiO ₄ and Li _1.2 Mn _0.294 Fe _0.392 Zr _0.042 SiO ₄ are preferred.

Furthermore, the lithium-based polyanion particles (B) have a core-shell structure having a core portion (inside) and a shell portion (surface layer portion) made of the lithium-based polyanion particles represented by the above formula (3) or (4). It may be formed.

Due to the core-shell structure of the lithium-based polyanion particles (B), a lithium-based polyanion with a high Mn content that is easily eluted from the lithium-based polyanion particles (B) into the electrolyte is placed in the core, and the shell is easily in contact with the electrolyte. By arranging a lithium-based polyanion having a low Mn content in the portion, it is possible to further improve the suppression of the deterioration of the cycle characteristics caused by the lithium-based polyanion particles and the assurance of safety. At this time, the core portion may be composed of one phase, or may be composed of two or more phases having different compositions. As a mode in which the core portion is composed of two or more phases, a structure in which a plurality of phases are concentrically layered and laminated, or a structure in which the composition changes transitionally from the surface of the core portion toward the center portion may be used. good.
Further, the shell portion may be formed outside the core portion, and may be composed of one phase like the core portion, or may be composed of two or more phases having different compositions.

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

The average particle size of the lithium-based polyanion particles (B) represented by the above formula (3) or (4) is dense with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). From the viewpoint of compositing, when the lithium-based polyanion particles (B) are represented by formula (3), the particle size is preferably 50 nm to 200 nm, more preferably 50 nm to 150 nm, and still more preferably 50 nm to 100 nm. be. When the lithium-based polyanion particles (B) are represented by formula (4), the particle size is preferably 20 nm to 200 nm, more preferably 20 nm to 150 nm, and still more preferably 20 nm to 100 nm.
The average particle diameter of the lithium-based polyanion particles (B) formed by forming a core-shell structure is It is preferably 50 nm to 200 nm, more preferably 50 nm to 150 nm, still more preferably 50 nm to 100 nm. , more preferably 20 nm to 150 nm, still more preferably 20 nm to 100 nm.

The lithium-based polyanion particles (B) represented by the above formula (3) or (4) have a lithium ion conductivity of 1×10 ⁻⁷ S/cm or more when pressurized at 25° C. and 20 MPa. Preferably, it is 1×10 ⁻⁶ S/cm or more. The upper limit of the lithium ion conductivity of the lithium-based polyanion particles (B) is not particularly limited.

The lithium-based polyanion particles (B) carry a lithium-based solid electrolyte (D) and carbon (C) on their surfaces. The mass ratio ((D):(C)) of the supported amount of the lithium-based solid electrolyte (D) and the supported amount of carbon (C) on the surfaces of these lithium-based polyanion particles (B) is 1:5 to 7: 1, preferably 1:3 to 6:1, more preferably 1:2 to 5:1.

Specifically, when the lithium-based polyanion particles (B) are represented by formula (3), the supported amount of the lithium-based solid electrolyte (D) is In 100% by mass of the total amount of supported lithium-based polyanion particles (B), it is preferably 0.1% by mass to 11% by mass, more preferably 0.5% by mass to 7% by mass, and still more preferably It is 1% by mass to 3% by mass. Further, when the lithium-based polyanion particles (B) are represented by the formula (4), the total amount of the lithium-based polyanion particles (B) supporting the lithium-based solid electrolyte (D) and carbon (C) is 100% by mass. Among them, it is preferably 0.1% by mass to 12% by mass, more preferably 0.5% by mass to 7% by mass, and still more preferably 1% by mass to 3% by mass.

Further, the amount of carbon (C) supported on the surface of the lithium-based polyanion particles (B) is 100% by mass of the lithium-based solid electrolyte (D) and the lithium-based polyanion particles (B) on which carbon (C) is supported. Among them, it is preferably 0.1% by mass to 12% by mass, more preferably 0.3% by mass to 7% by mass, and still more preferably 0.5% by mass to 5% by mass.

Furthermore, the total supported amount of the lithium-based solid electrolyte (D) and carbon (C) on the surface of the lithium-based polyanion particles (B) is, when the lithium-based polyanion particles (B) are represented by formula (3), , Lithium-based solid electrolyte (D) and lithium-based polyanion particles (B) on which carbon (C) is supported are preferably 2% by mass to 16% by mass, more preferably 2.5% in the total amount of 100% by mass. % to 15% by mass, more preferably 3% to 12% by mass. Further, when the lithium-based polyanion particles (B) are represented by the formula (4), the total amount of the lithium-based polyanion particles (B) supporting the lithium-based solid electrolyte (D) and carbon (C) is 100% by mass. Among them, it is preferably 2% by mass to 17% by mass, more preferably 2.5% by mass to 16% by mass, and still more preferably 3% by mass to 12% by mass.

On the surfaces of the lithium-based polyanion particles (B), the lithium-based solid electrolyte (D) and the carbon (C) supported together are supported. The lithium-based polyanion particles may carry the lithium-based solid electrolyte (D) so as to cover the entire surface thereof, and the lithium-based polyanion particles carry the lithium-based solid electrolyte (D) so as to cover the entire surface of the particles. (B) may carry carbon (C).

The thickness of the lithium-based solid electrolyte coating layer formed by the lithium-based solid electrolyte (D) supported on the entire surface of the lithium-based polyanion particles (B) is preferably 1 nm to 10 nm, more preferably. is 1 nm to 8 nm, more preferably 1 nm to 5 nm.
Here, the thickness of the lithium-based solid electrolyte coating layer refers to the lithium-based solid electrolyte coating layer on the surface of ten lithium-based polyanion particles (B) in TEM observation on the cross section of the lithium-based polyanion particles (B). means the average value of the measured values of the thickness, and the same meaning is used in the following description.

In the positive electrode active material composite for lithium ion secondary batteries of the present invention, the content of the lithium composite oxide secondary particles (A), and the lithium-based solid electrolyte (D) and carbon (C) supported on the surface The mass ratio ((A):(B)) to the content of the lithium-based polyanion particles (B) (including the supported amounts of the lithium-based solid electrolyte (D) and carbon (C)) is preferably from 95:5 to 55:45, more preferably 90:10 to 55:45, still more preferably 85:15 to 55:45.

The lithium-based solid electrolyte (D) supported on the surfaces of the lithium-based polyanion particles (B) has at least good lithium ion conductivity, and in the production method described later, the carbon source is used for carbonization. Since it needs to be formed in the firing process, it is a lithium-based solid electrolyte that can be obtained even if the firing atmosphere is reducing. Specific examples include 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 , and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) among others. ₃ is preferred.

The average particle diameter of the lithium-based solid electrolyte (D) is preferably 1 nm to 10 nm, more preferably 1 nm to 8 nm, still more preferably 1 nm to 5 nm.
Here, the average particle size of the lithium-based solid electrolyte (D) is identified by the diffraction contrast at the surface of the lithium-based polyanion particles (B) in TEM observation of the cross section of the lithium-based polyanion particles (B). , means the average value of the measured values of the particle size (long axis length) of several tens of lithium-based solid electrolyte particles, and the same meaning is used in the following description.

The carbon (C) carried on the surfaces of the lithium-based polyanion particles (B) together with the lithium-based solid electrolyte (D) is fired together with the lithium-based polyanion particles (B) and the carbon source (C'). By this, it is firmly supported on the surface of the lithium-based polyanion particles (B), or mixed with the lithium-based polyanion particles (B) while applying a compressive force and a shear force to the lithium-based polyanion particles (B). Firmly supported on the surface. The carbon source (C') that becomes carbon (C) by firing is selected from cellulose nanofibers (C'-1), lignocellulose nanofibers (C'-2), and water-soluble carbon materials (C'-3). The carbon (C) to be mixed while applying compressive force and shear force includes a water-insoluble carbon material (C4).

The cellulose nanofiber (C'-1) as the carbon source (C') is a skeletal component that accounts for about 50% of all plant cell walls. Carbon (C1) derived from cellulose nanofiber (C'-1) has a periodic structure. Such cellulose nanofibers (C'-1) have a fiber diameter of 1 nm to 100 nm and have good dispersibility in water. In addition, since the cellulose molecular chains constituting the cellulose nanofibers (C'-1) have a periodic structure formed by carbon, the particles are carbonized and combined with the lithium-based polyanion particles (B). good electronic conductivity can be imparted by being firmly supported on the surface of the

The lignocellulose nanofiber (C'-2) as the carbon source (C') has even better dispersibility in water than the cellulose nanofiber (C'-1). The carbon (C2) obtained by carbonizing the lignocellulose nanofibers (C'-2) forms a complex three-dimensional structure having a periodic structure derived from cellulose nanofibers and a three-dimensional network structure derived from lignin. , can be effectively supported on the lithium-based polyanion particles (B). The fiber diameter of such lignocellulose nanofiber (C'-2) is 30 nm to 1000 nm.

The water-soluble carbon material (C'-3) as the carbon source (C') is 0.4 g or more in terms of carbon atoms of the water-soluble carbon material (C'-3) in 100 g of water at 25 ° C. Preferably, it means a carbon material that dissolves in an amount of 1.0 g or more, and is present as carbon on the surfaces of the lithium-based polyanion particles (B) by being carbonized. Examples of such water-soluble carbon materials (C'-3) include one or more selected from sugars, polyols, polyethers, and organic acids. More specifically, for example, monosaccharides such as glucose, fructose, galactose and mannose; disaccharides such as maltose, sucrose and cellobiose; polysaccharides such as starch and dextrin; ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol and butane. polyols and polyethers such as diols, propanediol, polyvinyl alcohol and glycerin; and organic acids such as citric acid, tartaric acid and ascorbic acid. Among these, glucose, fructose, sucrose, and dextrin are preferred, and glucose is more preferred, from the viewpoint of enhancing solubility and dispersibility in a solvent and effectively functioning as a carbon source.

In addition, carbon (C1) derived from cellulose nanofibers (C'-1), carbon (C2) derived from lignocellulose nanofibers (C'-2), or water-soluble The amount of carbon (C3) derived from the carbon material (C'-3) in terms of atoms (amount of carbon supported) is confirmed as the amount of carbon measured using a carbon/sulfur analyzer for the lithium-based polyanion particles (B). can do.

The water-insoluble carbon material (C4) supported on the lithium-based polyanion particles (B) as carbon (C) means that the amount dissolved in 100 g of water at 25 ° C. is 0 in terms of carbon atoms of the water-insoluble carbon material (C4). It is a water-insoluble carbon material weighing less than 4 g and has electrical conductivity per se without being calcined. Such water-insoluble carbon materials (C4) include one or more selected from graphite, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black. Among them, graphite is preferable from the viewpoint of reducing the amount of adsorbed water. Graphite may be either artificial graphite (flaky, massive, earthy, graphene) or natural graphite. The average particle size of the water-insoluble carbon material (C4) is preferably 0.5 μm to 20 μm, more preferably 1.0 μm to 15 μm, from the viewpoint of composite formation.

The lithium-based polyanion particles (B) represented by the formula (3) or (4) in which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface are lithium composite oxide particles. It may be composited with the primary particles, or may be directly composited with part of the lithium composite oxide secondary particles (A) formed by agglomeration of the primary particles that are the lithium composite oxide particles.

The average particle size of the positive electrode active material composite for lithium ion secondary batteries 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 diameter of the positive electrode active material composite is smaller than 2 μm, the tap density is lowered and sufficient peel strength cannot be imparted to the prepared electrode, which may deteriorate the cycle characteristics of the battery. On the other hand, when the average particle size is larger than 30 μm, it is difficult to uniformly coat the electrode, making it impossible to obtain a uniform electrode, which may reduce the discharge capacity of the battery.
The tap density of the positive electrode active material composite for lithium ion secondary batteries of the present invention is preferably 1.0 g/cm ³ to 2.0 g/cm ³ , more preferably 1.2 g/cm ³ to 2.0 g/cm 3 . 0 g/cm ³ . If the positive electrode active material composite has a tap density of less than 1.0 g/cm ³ , the cycle characteristics of the battery may deteriorate as described above.

The positive electrode active material composite for lithium ion secondary batteries of the present invention is prepared by the following steps (I) to (IV):
(I) a step of preparing a slurry containing a lithium compound, a metal compound containing at least an iron compound or a manganese compound, a phosphoric acid compound or a silicate compound, and then subjecting it to a hydrothermal reaction to obtain lithium-based polyanion primary particles;
(II) a step of preparing a slurry containing the obtained lithium-based polyanion primary particles and a raw material compound of the lithium-based solid electrolyte (D), followed by spray drying to obtain granules;
(III) a step of calcining the obtained granules to obtain a pre-granulated material (b) having a porosity of 45% by volume to 80% by volume, and (IV) the obtained pre-granulated material (b) and the lithium composite oxide secondary particles (A) are mixed while applying compressive force and shear force, and while disintegrating the pre-granulated material (b), the lithium-based A step of supporting a solid electrolyte (D) and carbon (C) and compounding the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B),
Either the slurry prepared in step (I) or the slurry prepared in step (II) is a slurry to which a carbon source (C') is further added, or A water-insoluble carbon material (C4) is added together with the particles (b) and the lithium composite oxide secondary particles (A), and the positive electrode active material for a lithium ion secondary battery is mixed while applying compressive force and shear force. It can be obtained by a method for producing a composite. In this way, by going through the step (III) of obtaining the pre-granulated material (b) having a high porosity composed of the lithium-based polyanion particles (B), the primary particles of the lithium-based polyanion are firmly agglomerated and obtained. Compared to the conventional manufacturing method using hard secondary particles, the pregranulated material (b) can be easily disintegrated and finely granulated in the subsequent step (IV) without applying an excessive load. Such pre-granulated material (b) separates and releases the lithium-based polyanion particles (B) while being finely granulated, and the lithium-based polyanion particles (B) are formed on the surfaces of the lithium composite oxide secondary particles (A). It is possible to support the with efficient and good contact.
When the carbon source (C') is used, it may be added to either the slurry prepared in step (I) or the slurry prepared in step (II). As the carbon source (C'), cellulose nanofibers (C'-1), lignocellulose nanofibers (C'-2), or water-soluble carbon materials (C'-3) may be used in the same manner as described above. .

The step (I) provided in the production method of the present invention includes subjecting a lithium compound, a metal compound containing at least an iron compound or a manganese compound, a phosphoric acid compound or a silicate compound to a hydrothermal reaction to obtain primary particles of a lithium-based polyanion. It is a process.
More specifically, the following steps (i)-(ii):
(i) mixing a mixture (b-1) containing a lithium compound with a phosphate compound or a silicate compound to obtain a precursor (b-2);
(ii) The obtained precursor (b-2) and a slurry (b-3) containing a metal compound containing at least an iron compound or a manganese compound are subjected to a hydrothermal reaction to subject the lithium-based polyanion primary particles (b- 4) obtaining
is preferably provided.
Here, in step (ii), a carbon source (C') may be added in preparing the slurry (b-3). In that case, the carbon source (C') should not be added to the slurry prepared in the subsequent step (II).

Step (i) is a step of mixing a mixture (b-1) containing a lithium compound with a phosphoric acid compound or a silicate compound to obtain a precursor (b-2).
Lithium compounds that can be used include lithium hydroxide (eg, LiOH, LiOH.H ₂ O), lithium carbonate, lithium sulfate, and lithium acetate. Among them, lithium hydroxide is preferred.
The content of the lithium compound in the mixture (b-1) is preferably 5 parts by mass to 50 parts by mass, more preferably 7 parts by mass to 45 parts by mass, relative to 100 parts by mass of water. More specifically, when the phosphoric acid compound is used in step (i), the content of the lithium compound in the mixture (b-1) is preferably 5 parts by mass to 50 parts by mass with respect to 100 parts by mass of water. and more preferably 10 parts by mass to 45 parts by mass. Further, when a silicate compound is used, the content of the lithium compound in the mixture (b-1) is preferably 5 parts by mass to 40 parts by mass, more preferably 7 parts by mass to 100 parts by mass of water. 35 parts by mass.

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

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

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

The silicic acid compound used in step (i) is not particularly limited as long as it is a reactive silica compound, and examples thereof include amorphous silica, Na ₄ SiO ₄ (eg, Na ₄ SiO ₄ ·H ₂ O), and the like. .

The mixture (b-1) after mixing the phosphoric acid compound or silicic acid compound preferably contains 2.0 mol to 4.0 mol of lithium per 1 mol of phosphoric acid or silicic acid, and 2.0 It is more preferable to contain mol to 3.1 mol, and the lithium compound and the phosphoric acid compound or silicic acid compound may be used so as to achieve such an amount. More specifically, when a phosphoric acid compound is used in step (i), the mixture (b-1) after mixing the phosphoric acid compound contains 2.7 mol to 3 mol of lithium per 1 mol of phosphoric acid. .3 mol, more preferably 2.8 mol to 3.1 mol, and when a silicic acid compound is used in step (i), the mixture after mixing the silicic acid compound (b- 1) preferably contains 2.0 mol to 4.0 mol, more preferably 2.0 mol to 3.0 mol, of lithium per 1 mol of silicic acid.

By purging nitrogen into the mixture (b-1) after mixing the phosphoric acid compound or the silicic acid compound, the reaction in the mixture (b-1) is completed, and the precursor of the lithium-based polyanion particles Body (b-2) is produced in mixture (b-1). When nitrogen is purged, the reaction can proceed with a reduced dissolved oxygen concentration in the mixture (b-1), and the resulting mixture (b-1) containing the precursor (b-2) ) is also effectively reduced, it is possible to suppress the oxidation of iron compounds, manganese compounds, etc. added in the next step. In the mixture (b-1) containing the precursor (b-2), the precursor (b-2) of the lithium-based polyanion particles exists as fine dispersed particles. Such a precursor (b-2) is obtained as trilithium phosphate (Li ₃ PO ₄ ), for example, when a phosphoric acid compound is used in step (i).

The pressure during nitrogen purging is preferably 0.1 MPa to 0.2 MPa, more preferably 0.1 MPa to 0.15 MPa. The temperature of the mixture (b-1) after mixing the phosphoric acid compound or silicic acid compound is preferably 20°C to 80°C, more preferably 20°C to 60°C. For example, when a phosphate compound is used in step (i), the reaction time is preferably 5 to 60 minutes, more preferably 15 to 45 minutes.
Further, when purging with nitrogen, it is preferable to stir the mixture (b-1) after mixing the phosphoric acid compound or the silicic acid compound from the viewpoint of making the reaction proceed well. The stirring speed at this time is preferably 200 rpm to 700 rpm, more preferably 250 rpm to 600 rpm.

In addition, from the viewpoint of more effectively suppressing oxidation on the surface of the dispersed particles of the precursor (b-2) and miniaturizing the dispersed particles, the mixture (b-1 ) is preferably 0.5 mg/L or less, more preferably 0.2 mg/L or less.

In the step (ii), the precursor (b-2) obtained in the step (i) and a slurry (b-3) containing a metal compound containing at least an iron compound or a manganese compound are subjected to a hydrothermal reaction. to obtain lithium-based polyanion primary particles (b-4). The precursor (b-2) obtained in the above step (i) is used as the mixture (b-1) as a precursor for lithium-based polyanion particles, and a metal compound containing at least an iron compound or a manganese compound is added thereto. It is preferable to add it and use it as a slurry (b-3). As a result, the target lithium-based polyanion primary particles (b-4) become extremely fine particles while simplifying the process.

Iron compounds that can be used include iron acetate, iron nitrate, iron sulfate, and the like. These may be used individually by 1 type, and may be used in combination of 2 or more types. Among them, iron sulfate is preferable from the viewpoint of improving the battery characteristics of the lithium-based polyanion particles (B).

Manganese compounds that can be used include manganese acetate, manganese nitrate, manganese sulfate, and the like. These may be used individually by 1 type, and may be used in combination of 2 or more types. Among them, manganese sulfate is preferable from the viewpoint of improving the battery characteristics of the lithium-based polyanion particles (B).

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

Furthermore, metal (M ³ or M ⁴ ) salts other than iron compounds and manganese compounds may be used as the metal compound, if necessary. M ³ or M ⁴ in the metal compound has the same definition as M ³ or M ⁴ in the above formulas (III) to (IV), and examples of such metal compounds include sulfates, halogen compounds, organic acid salts, and water A Japanese product or the like can be used. These may be used individually by 1 type, and may be used 2 or more types. Among them, it is more preferable to use a sulfate from the viewpoint of improving battery physical properties.
When these metal (M ³ or M ⁴ ) compounds are used, the total amount of iron compound, manganese compound and metal (M ³ or M ⁴ ) salt added is the same as the precursor (b- It is preferably 0.99 mol to 1.01 mol, more preferably 0.995 mol to 1.005 mol, per 1 mol of phosphoric acid or silicic acid in 2).

Here, when the carbon source (C') is further added to prepare the slurry (b-3), the amount of the carbon source (C') added is the precursor (b- 2) With respect to 100 parts by mass, it is preferably 0.01 to 15 parts by mass, more preferably 0.02 to 10 parts by mass, and still more preferably 0.03 to 5 parts by mass.

The amount of water used in the hydrothermal reaction is determined from the viewpoint of the solubility of the metal compound used, the ease of stirring, the efficiency of synthesis, etc., and the phosphoric acid or It is preferably 10 mol to 50 mol, more preferably 12.5 mol to 45 mol, per 1 mol of silicate ion. More specifically, when the ions contained in the slurry (b-3) are phosphate ions, the amount of water used in the hydrothermal reaction is preferably 10 mol to 30 mol, It is more preferably 12.5 mol to 25 mol. Further, when the ions contained in the slurry (b-3) are silicate ions, the amount of water used in the hydrothermal reaction is preferably 10 mol to 50 mol, more preferably 12 mol. .5 mol to 45 mol.

In step (ii), the order of addition of the iron compound, manganese compound and metal ⁽ M3 or ^M4 ) compound is not particularly limited. The same is true when adding the carbon source (C'). Moreover, while adding these metal compounds, you may add antioxidant as needed. Examples of such antioxidants include sodium sulfite (Na ₂ SO ₃ ), sodium hydrosulfite (Na ₂ S ₂ O ₄ ), aqueous ammonia, and the like. From the viewpoint of preventing suppression of the formation of the lithium-based polyanion primary particles (b-4) due to excessive addition, the amount of the antioxidant added is an iron compound, a manganese compound, and a metal used as necessary. It is preferably 0.01 mol to 1 mol, more preferably 0.03 mol to 0.5 mol, per 1 mol of the (M ³ or M ⁴ ) compound.

Lithium-based polyanion primary particles (b-4) in a slurry (b-3) obtained by adding an iron compound, a manganese compound, and optionally a metal (M ³ or M ⁴ ) compound and an antioxidant. The content is preferably 10% to 50% by mass, more preferably 15% to 45% by mass, still more preferably 20% to 40% by mass.

The hydrothermal reaction in step (ii) may be carried out at 100°C or higher, preferably from 130°C to 180°C. The hydrothermal reaction is preferably carried out in a pressure vessel, and when the reaction is carried out at 130°C to 180°C, the pressure at this time is preferably 0.3 MPa to 0.9 MPa, and the reaction is carried out at 140°C to 160°C. The pressure when carrying out is preferably 0.3 MPa to 0.6 MPa. The hydrothermal reaction time is preferably 6 minutes to 48 hours, more preferably 12 minutes to 24 hours.
The obtained lithium-based polyanion primary particles (b-4) are lithium-based polyanion particles represented by the above formulas (3) to (4), and the lithium-based polyanion primary particles (b-4 ) is washed with water and dried to isolate the lithium-based polyanion particles as primary particles. Freeze drying and vacuum drying are used as drying means.

The BET specific surface area of the resulting lithium-based polyanion primary particles (b-4) is preferably 5 m ² /g to 40 m ² /g, more preferably 5 m ² /g, from the viewpoint of effectively reducing the amount of adsorbed water. g to 20 m ² /g. If the BET specific surface area of the lithium-based polyanion primary particles (b-4) is less than 5 m ² /g, the lithium-based polyanion particles (B) may become too large. Also, if the BET specific surface area exceeds 40 m ² /g, the amount of water adsorbed by the positive electrode active material composite for a secondary battery increases, which may affect the battery characteristics.

In the step (II) provided in the production method of the present invention, a slurry containing the obtained lithium-based polyanion primary particles and a raw material compound of the lithium-based solid electrolyte (D) is prepared, and then spray-dried to obtain granules. It is a process. More specifically, after preparing the slurry (b-5) containing the lithium-based polyanion primary particles (b-4) obtained in step (I) and the raw material compound of the lithium-based solid electrolyte (D), the slurry ( b-5) is spray-dried to obtain granules (b-6) containing the lithium-based polyanion primary particles (b-4) and the raw material compound of the lithium-based solid electrolyte (D).
Here, a carbon source (C') may be added in preparing the slurry (b-5). In that case, the carbon source (C') should not be added to the slurry prepared in the step (I). Therefore, in any case, the slurry (b-5) to be finally subjected to spray drying contains the carbon source (C'), and the resulting granules (b-6) also contain the carbon source ( C') will be included. Then, by going through the next step (III) using such granules (b-6), carbon (C) is carried on the surfaces of the lithium-based polyanion particles (B).
In the production method of the present invention, when the carbon source (C') is not used in the steps (I) and (II), a water-insoluble carbon material (C4) may be used in the step (IV) described later. .

The content of the lithium-based polyanion primary particles (b-4) in the slurry (b-5) is preferably 10 parts by mass to 30 parts by mass, more preferably 15 parts by mass to 30 parts by mass, relative to 100 parts by mass of water. part by mass. A water-washed filter cake containing the above-described lithium-based polyanion primary particles (b-4) may be used so as to achieve such a content.

The raw material compound of the lithium-based solid electrolyte (D) that constitutes the granule (b-6) is fired in the next step (III) to form the lithium-based solid electrolyte (D). The raw material compound to be used is preferably one that dissolves in the slurry (b-5), and each element constituting the lithium-based solid electrolyte (D), specifically, water of titanium, lithium, aluminum, silicon, boron, and phosphorus. Examples include, but are not limited to, oxides, carbonates, sulfates, acetates, and the like.

When the surface of the lithium-based polyanion particles (B) is calcined in the next step (III) to support the lithium-based solid electrolyte (D) generated from the raw material compound, the slurry (b-5) has the above The total content of the raw material compounds of the lithium-based solid electrolyte (D) is 100% by mass of the total amount of the lithium-based polyanion particles (B) and the lithium-based solid electrolyte (D) and carbon (C) supported on the surface of the particles. On the other hand, it is desirable that the amount is 0.1% by mass to 11% by mass. Specifically, it is preferably 0.05 to 40 parts by mass, more preferably 0.05 to 20 parts by mass, relative to 100 parts by mass of water in the slurry (b-5).

When the carbon source (C') is added to the slurry (b-5) in step (II), the cellulose nanofibers (C'-1) and/or lignocellulose nanofibers (C' The content of -2) is the amount in terms of carbon atoms, relative to the total amount of 100% by mass of the lithium-based polyanion particles (B), the lithium-based solid electrolyte (D) supported on the surface of such particles, and carbon (C) , 0.1% to 12% by weight.

Specifically, for example, when cellulose nanofibers (C'-1) and/or lignocellulose nanofibers (C'-2) are used as the carbon source (C'), the amount of the carbon source (C') added is preferably 0.05 to 40 parts by mass, more preferably 0.05 to 15 parts by mass in terms of carbon atoms, per 100 parts by mass of water in the slurry (b-5). When the water-soluble carbon material (C'-3) is used as the carbon source (C'), the amount of the carbon source (C') added is carbon The atomic equivalent amount is preferably 0.05 to 35 parts by mass, more preferably 0.05 to 13 parts by mass.
Furthermore, when using cellulose nanofibers (C'-1) and/or lignocellulose nanofibers (C'-2) and a water-soluble carbon material (C'-3) as the carbon source (C'), the slurry ( The total content of these carbon sources (C′) in b-5) is the total amount of the lithium-based polyanion particles (B) and the lithium-based solid electrolyte (D) supported on the surface of the particles and carbon (C) 100 It may be 0.1% by mass to 12% by mass in terms of carbon atoms.

Finally, the obtained slurry (b-5) contains cellulose nanofibers (C'-1) and lignocellulose nanofibers (C') as carbon sources (C') together with lithium-based polyanion particles (B). -2) and/or a water-soluble carbon material (C'-3) will be included. In preparing such a slurry (b-5), from the viewpoint of uniformly dispersing the lithium-based polyanion particles (B) and the carbon source (C′), it is preferable to perform treatment using a disperser (homogenizer). Such dispersers include, for example, disaggregators, beaters, low-pressure homogenizers, high-pressure homogenizers, grinders, cutter mills, ball mills, jet mills, short-screw extruders, twin-screw extruders, ultrasonic stirrers, household juicer mixers, and the like. mentioned. Among them, an ultrasonic stirrer is preferable from the viewpoint of dispersion efficiency. The degree of dispersion uniformity of the slurry (b-5) can be quantitatively evaluated, for example, by light transmittance using a UV/visible light spectrometer or viscosity using an E-type viscometer. It can be easily evaluated by confirming that the degree of cloudiness is uniform. The time for treatment with a disperser is preferably 1 minute to 30 minutes, more preferably 2 minutes to 15 minutes.

When cellulose nanofibers (C′-1) and/or lignocellulose nanofibers (C′-2) are used as the carbon source (C′), the slurry (b-5) is composed of cellulose nanofibers still in an aggregated state. From the viewpoint of effectively removing fibers, wet classification is preferred. A sieve or a commercially available wet classifier can be used for wet classification. The opening of the sieve may vary depending on the fiber length of the cellulose nanofiber (C'-1) and/or lignocellulose nanofiber (C'-2) used, but from the viewpoint of work efficiency, it is around 150 μm. preferable.

As described above, the solid content concentration of the obtained slurry (b-5) is preferably 10% by mass to 35% by mass, more preferably 15% by mass to 30% by mass.

The resulting slurry (b-5) is then spray-dried to obtain granules (b-6). Such granules (b-6) are formed of lithium-based polyanion particles (B) carrying a lithium-based solid electrolyte (D) and carbon (C) on their surfaces through the next step (III). It becomes a preliminary granule (b). In the production method of the present invention, avoiding the use of robust secondary particles obtained by firmly aggregating the lithium-based polyanion primary particles (b-4), it is possible to easily disintegrate without applying an excessive load. Since the pre-granulated material (b) is used, the lithium-based polyanion particles (B) having carbon (C) supported on the surface, which constitutes the pre-granulated material (b), are subjected to excessive shearing force, etc. can be supported on the surface of the lithium composite oxide secondary particles (A) without the need for

The temperature of hot air during spray drying is preferably 110°C to 160°C, more preferably 120°C to 140°C. The ratio (G/S) of the hot air supply amount G (L/min) to the slurry (b-5) supply amount S (L/min) is preferably 500 to 10,000, more preferably 1,000 to 9,000.

The particle size of the granules (b-6) obtained in step (II) is preferably 5 μm to 14 μm, more preferably 5 μm to 12 μm, in terms of the _D50 value in the particle size distribution based on the laser diffraction/scattering method. be.
Here, the _D50 value in particle size distribution measurement is a value obtained by a volume-based particle size distribution based on a laser diffraction/scattering method, and the _D50 value means a particle size (median diameter) at a cumulative 50%. .

The step (IV) provided in the production method of the present invention includes firing the granules (b-6) obtained in the step (II) to obtain a pre-granulated product ( b) is obtained. Through the step (IV), the lithium-based solid electrolyte (D) and carbon (C) are supported more firmly on the surfaces of the lithium-based polyanion particles (B) constituting the pregranulated material (b), It is possible to form a pregranulated material (b) having a porosity adjusted to 45% to 80% by volume and having an appropriate degree of disintegration.

The firing temperature is selected from the viewpoint of effectively producing the lithium-based solid electrolyte (D), the viewpoint of effectively carbonizing the carbon source (C′), and the porosity of the pregranulated material (b) from 45% to 80% by volume. The temperature is preferably 500°C to 800°C, more preferably 600°C to 770°C, and particularly preferably 650°C to 750°C, from the viewpoint of adjusting the temperature to a suitable disintegration property. The firing time is preferably 10 minutes to 3 hours, more preferably 30 minutes to 1.5 hours.

The porosity of the pre-granulated product (b) composed of the lithium-based polyanion particles (B) on which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface is 45 vol. % to 80% by volume, preferably 50% to 80% by volume.

Further, the tap density of the pre-granulated material (b) composed of the lithium-based polyanion particles (B) on which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface is preferably less than 1.0 g/cm ³ . and more preferably 0.6 g/cm ³ to 0.9 g/cm ³ .

Furthermore, the average particle size of the pre-granulated product (b) composed of the lithium-based polyanion particles (B) on which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface is the particle size based on the laser diffraction/scattering method. The D ₅₀ value in the distribution is preferably between 5 μm and 15 μm, more preferably between 5 μm and 12 μm.

The collapse strength of the pre-granulated product (b) comprising the lithium-based polyanion particles (B) on which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface is preferably 1.8 KN/mm or less, More preferably, it is 1.75 KN/mm or less. The collapse strength indicates the ease with which the pre-granulated material (b) composed of the lithium-based polyanion particles (B) supporting the lithium-based solid electrolyte (D) and carbon (C) on the surfaces thereof collapses due to compression. , means the value obtained by the following formula (5).
Collapse strength (KN/mm) of pregranulated material (b) = 10/(t ₀ - t ₁₀ ) (5) t ₀ in formula (5) is a cylindrical container having a diameter of 20 mm. 3 g of the pre-granulated material (b) composed of the lithium-based solid electrolyte (D) and the lithium-based polyanion particles (B) supporting carbon (C) was added, and tapping by dropping from a height of 1 cm was repeated 10 times. Shows the layer thickness (mm) of the pre-granulated material (b) in the densely-packed state afterward, and t ₁₀ is the thickness when a load of 10 KN is applied from above to the pre-granulated material (b) in such a densely-packed state. The layer thickness (mm) of the pregranulated material (b) is shown.

In the step (IV) provided in the production method of the present invention, the pre-granulated material (b) obtained in the step (III) and the lithium composite oxide secondary particles (A) are compressed while applying a compressive force and a shear force. While mixing and collapsing the pre-granulated material (b), the lithium-based polyanion particles (B) carrying the lithium-based solid electrolyte (D) and carbon (C) on the surface (B) and the lithium composite oxide secondary particles ( A) is a step of combining. Through such a step, fine particles obtained by collapsing the pre-granulated material (b) are formed on the surface of the lithium composite oxide secondary particles (A), and the lithium-based solid electrolyte (D) and carbon are formed on the surface thereof. A positive electrode active material composite for a lithium ion secondary battery can be obtained in which the lithium-based polyanion particles (B) supporting (C) are supported so as to cover a dense and wide area.

In step (IV), before mixing while applying compressive force and shearing force, the mixture of secondary particles of lithium composite oxide (A) and the pre-granulated material (b) is sufficiently dry-mixed. preferable. The method of dry mixing is preferably mixing with a normal dry mixer such as a ball mill or V blender, and more preferably mixing with a planetary ball mill capable of rotating and revolving.

The process of mixing while applying compressive force and shear force (hereinafter also referred to as "combining") is preferably performed in a closed vessel equipped with an impeller, rotor tool, or the like. Examples of devices equipped with such a closed container include high-speed shear mills, blade type kneaders, high-speed mixers, etc. Specifically, for example, particle design device COMPOSI, mechano hybrid, high-performance fluidized mixer FM mixer (Japan (manufactured by Coke Kogyo Co., Ltd.) fine particle composite device Mechanofusion, Nobilta (manufactured by Hosokawa Micron Corporation), surface modification device Miraro, hybridization system (manufactured by Nara Machinery Co., Ltd.), and Eirich Intensive Mixer (manufactured by Nihon Eirich Co., Ltd.) are preferably used. be able to. As for the conditions for the compounding treatment, the temperature is preferably 5°C to 80°C, more preferably 10°C to 50°C. Moreover, although the atmosphere is not particularly limited, it is preferably an inert gas atmosphere or a reducing gas atmosphere.

More specifically, for example, when using Nobilta (manufactured by Hosokawa Micron Corporation), which is a dry particle compounding device equipped with an impeller, as a device for compounding, the number of rotations of the impeller is the same as the pregranulated material (b ) is efficiently collapsed, and the lithium-based polyanion particles (B) in which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface of the lithium composite oxide secondary particles (A) are good. From the viewpoint of obtaining the composite oxide supported so as to cover the surface, the speed is preferably 2000 rpm to 6000 rpm, more preferably 2000 rpm to 4000 rpm. The time for complexing is preferably 1 to 10 minutes, more preferably 1 to 7 minutes.
In addition, when an Eirich Intensive Mixer (manufactured by Japan Eirich Co., Ltd.), which is a high-speed stirring mixer equipped with a rotor tool, is used as a device for performing such compositing, the rotation speed of the rotor tool is preferably 2000 rpm to 8000 rpm. Yes, more preferably 2000 rpm to 6000 rpm. The time for complexing is preferably 1 to 10 minutes, more preferably 1 to 7 minutes.

In the step (IV), the time for the composite and/or the rotation speed of the impeller or the like depends on the amount of the mixture of the lithium composite oxide secondary particles (A) and the pregranulated material (b) put into the closed container. should be adjusted accordingly. 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, while the pre-granulated material (b) is well disintegrated, lithium composite oxidation is performed. It is possible to perform a process of compositing the secondary particles (A) and the lithium-based polyanion particles (B) on which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface, and the lithium composite On the surface of the oxide secondary particles (A), the lithium-based polyanion particles (B) in which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface are supported so as to be well composited and coated. It is possible to obtain a positive electrode active material composite for a lithium ion secondary battery.
For example, when the compounding is performed in a closed container equipped with an impeller rotating at a speed of 2000 rpm to 5000 rpm for 1 minute to 8 minutes, the amount of the mixture put into the closed container is Among them, it is preferably 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 containing the mixture.

The amount of lithium composite oxide secondary particles (A) to be combined in step (IV), and the amount of lithium-based solid electrolyte (D) and lithium-based polyanion particles (B) having carbon (C) supported on their surfaces. The amount and mass ratio (particles (A):particles (B)) is such that the lithium-based solid electrolyte (D) and carbon (C) are well supported on the surface of the lithium composite oxide secondary particles (A). From the viewpoint of supporting the lithium-based polyanion particles (B), the ratio is preferably 95:5 to 60:40, more preferably 92:8 to 65:35, and still more preferably 90:10 to 70:30. be. The amount of the pregranulated material (b) in the mixture may be adjusted so as to achieve such an amount.

In the production method of the present invention, in addition to the above method, a water-insoluble carbon material (C4) is used as carbon (C) in step (IV) without using any carbon source (C′) in the above step. good too. In this case, the lithium-based polyanion particles (B) obtained in step (III) have only the lithium-based solid electrolyte (D) supported on their surfaces, and in step (IV), the pre-granulated material (b) and The water-insoluble carbon material (C4) may be added to the lithium composite oxide secondary particles (A) and mixed while applying compressive force and shear force. When adding the water-insoluble carbon material (C4) in step (IV), the amount of lithium composite oxide secondary particles (A) and the lithium-based polyanion particles ( The mass ratio (particles (A): (particles (B) + water-insoluble carbon material (C4))) to the total amount of B) and the water-insoluble carbon material (C4) is preferably 95:5 to 60:40. , more preferably 92:8 to 65:35, still more preferably 90:10 to 70:30. The blending amounts of the pregranulated material (b) and the water-insoluble carbon material (C4) in the mixture may be adjusted so as to achieve such amounts.

In addition, on the surface of the lithium composite oxide secondary particles (A), the lithium-based solid electrolyte (D) and the lithium-based polyanion particles (B) supporting carbon (C) are composited and coated on the surface. The degree of loading is determined by the peak intensity ratio ((Ni2p _3/2 peak intensity) / (P2p peak intensity + C1s peak intensity)) by X-ray photoelectron spectroscopy (XPS), that is, the lithium composite oxide secondary Peak intensity of Ni2p _3/2 released from particles (A), P2p and C1s released from lithium-based polyanion particles (B) having lithium-based solid electrolyte (D) and carbon (C) supported on the surface. It can be confirmed by the value of the peak intensity ratio. Specifically, when the obtained positive electrode active material composite for a lithium ion secondary battery is irradiated with soft X-rays of several keV, from the site irradiated with such soft X-rays, Since photoelectrons with an energy value of are emitted, the peak intensity corresponding to trivalent Ni obtained by analyzing the peak of Ni2p _3/2 emitted from the lithium composite oxide secondary particles (A) and the surface By comparing the total peak intensity of P2p and C1s released from the lithium-based polyanion particles (B) on which the lithium-based solid electrolyte (D) and carbon (C) are supported, the positive electrode for lithium ion secondary batteries The area ratio of the material forming the surface of the active material composite, that is, the lithium-based polyanion particles (B) supporting the lithium-based solid electrolyte (D) and carbon (C) on the surface is the lithium composite oxide. The degree of support so as to cover the next particle (A) can be seen.

More specifically, the positive electrode active material composite for a lithium ion secondary battery produced according to the present invention has a peak intensity ratio by XPS from the viewpoint of ensuring excellent discharge characteristics and safety in the resulting secondary battery. ((Ni2p _3/2 peak intensity) / (P2p peak intensity + C1s peak intensity)) is usually 0.04 or less, preferably 0.03 or less, more preferably 0.02 or less. .

Furthermore, regarding the peak intensity ratio by XPS, by comparing the XPS peak intensity ratio before and after applying a certain shear force to the obtained positive electrode active material composite for lithium ion secondary batteries, the lithium composite oxide secondary The coating strength of the lithium-based polyanion particles (B) carrying the lithium-based solid electrolyte (D) and carbon (C) on the surfaces of the particles (A) can be evaluated.

Specifically, 2 g of the obtained positive electrode active material composite for a lithium ion secondary battery and 10 g of N-methyl-2-pyrrolidone were stirred and kneaded for 3 minutes at 2000 rpm using a high-speed mixer (Filmix 40L model manufactured by Primix). For the positive electrode active material composite for a lithium ion secondary battery obtained by drying the slurry obtained by hot air drying, the peak intensity ratio by XPS ((peak intensity of Ni2p _3/2 ) / ( After obtaining the peak intensity of P2p + peak intensity of C1s)), the ratio to the XPS peak intensity ratio before applying the shear force ((peak intensity ratio after applying shear force) / (before applying shear force (This ratio is hereinafter referred to as the "coating strength"). The smaller the value of this coating strength, the closer it is to 1, the more strongly the secondary particles of lithium composite oxide are coated with the lithium-based polyanion particles.

Lithium composite oxide secondary particles (A) used in step (IV) (NCM-based composite oxide secondary particles represented by the above formula (1) or NCA-based composite oxide secondary particles represented by the above formula (2) secondary particles) may be obtained by the following production method.
To obtain the NCM-based composite oxide secondary particles (A) represented by the above formula (2), mixed powder containing a lithium compound, a nickel compound, a cobalt compound and a manganese compound is fired. Specifically, it is preferable to first dissolve a nickel compound, a cobalt compound, and a manganese compound in water so as to obtain a desired composition of a lithium composite oxide to obtain an aqueous solution a. Examples of such nickel compounds, cobalt compounds and manganese compounds include sulfates, nitrates, carbonates, acetates, oxalates, oxides, hydroxides and halides of these metal elements. Specific examples include nickel sulfate, cobalt sulfate, manganese sulfate, nickel acetate, cobalt acetate, and manganese acetate, but are not limited to these.
In this step, if necessary, Mg, Ti, Nb, Fe, Cr, Mg, Ti, Nb, Fe, Cr, as a metal (M ¹ ) element substituting a part of the lithium composite oxide so as to obtain a desired composition of the lithium composite oxide. One or more elements selected from Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Ge may be mixed. .

Next, an alkaline solution is added to the aqueous solution a to form an aqueous solution b, and the dissolved metal components are coprecipitated by a neutralization reaction while stirring to form a metal composite hydroxide. The alkaline solution used here is preferably added dropwise in an amount sufficient to keep the aqueous solution b at pH 10-14. As such an alkaline solution, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, or the like can be used, and sodium hydroxide, sodium carbonate, or a mixed solution thereof is preferably used.

The temperature of the aqueous solution b during the neutralization reaction is preferably 30°C or higher, more preferably 30°C to 60°C. The stirring time of the aqueous solution b is preferably 30 minutes to 120 minutes, more preferably 30 minutes to 60 minutes. After stirring, the metal composite hydroxide may be recovered by filtering the aqueous solution b. The recovered metal composite hydroxide is preferably washed with water and then dried.

Next, the recovered metal composite hydroxide and the lithium compound are dry-mixed so as to obtain the composition of the NCM-based composite oxide, and the obtained mixed powder is fired in an oxygen atmosphere. Examples of the lithium compound used here include lithium hydroxide or its hydrate, lithium peroxide, lithium nitrate, and lithium carbonate. In the dry mixing of the metal composite hydroxide and the lithium compound, an ordinary dry mixer or mixing granulator such as a ball mill or V-blender can be used, and a planetary ball mill capable of rotating and revolving is more preferably used.

Firing of the mixed powder is preferably carried out in two steps (temporary firing and final firing). By performing the two-stage firing, in the temporary firing, after removing thermally decomposed components such as water molecules and carbon dioxide from the hydroxides and carbonates in the mixed powder, the main firing is performed, which is efficient. NCM-based composite oxide secondary particles (A) can be obtained. The conditions for calcination are not particularly limited, but the rate of temperature increase from room temperature is preferably 1° C./min to 20° C./min. Moreover, the firing atmosphere is preferably an air atmosphere or an oxygen atmosphere. The firing temperature is preferably 700°C to 1000°C, more preferably 650°C to 750°C. Furthermore, the firing time is preferably 3 to 20 hours, more preferably 4 to 6 hours.
After pulverizing the obtained calcined material with a mortar or the like, it is preferable to mix an appropriate amount of binder, granulate, and finally calcine. The fired product obtained after the main firing is the NCM-based composite oxide secondary particles (A).

The conditions for the main sintering are not particularly limited, but the heating rate is preferably 1° C./min to 20° C./min from room temperature again. Moreover, the firing atmosphere is preferably an air atmosphere or an oxygen atmosphere. The sintering temperature is 700° C. to 1200° C. from the viewpoint of controlling the average particle diameter of the primary particles of the NCM-based composite oxide that constitute the NCM-based composite oxide secondary particles (A) obtained after the main sintering to a desired value. °C, more preferably 700°C to 1000°C, even more preferably 750°C to 900°C. Further, the firing time is preferably 3 hours to 20 hours, more preferably 8 hours to 10 hours.
For such two-step firing, electric furnaces, rotary kilns, tubular furnaces, pusher furnaces, etc., in which the oxygen concentration in the gas atmosphere is adjusted to 20% by mass or more, such as an oxygen atmosphere, a dry air atmosphere that has been subjected to dehumidification and decarbonation treatment. etc. can be used.

To obtain the NCA-based composite oxide secondary particles (A) represented by the above formula (2), a mixed powder containing a lithium compound, a nickel compound, a cobalt compound and an aluminum compound is fired. Specifically, it is preferable to first dissolve a nickel compound, a cobalt compound, and an aluminum compound in water so as to obtain a desired composition of a lithium composite oxide to obtain an aqueous solution a'. Examples of such nickel compounds, cobalt compounds and aluminum compounds include sulfates, nitrates, carbonates, acetates, oxalates, oxides, hydroxides and halides of these metal elements. Specific examples include nickel sulfate, cobalt sulfate, aluminum sulfate, nickel acetate, cobalt acetate, and aluminum acetate, but are not limited to these.
In this process, if necessary, Mg, Ti, Nb, Fe, Cr, Mg, Ti, Nb, Fe, Cr, etc. are used as metal (M ² ) elements to substitute a part of the lithium metal composite oxide so as to obtain a further desired composition of the composite oxide. One or more elements selected from Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Ge may be mixed.

Next, an alkaline solution is added to the aqueous solution a′ to form an aqueous solution b′, and the dissolved metal components are coprecipitated by a neutralization reaction while stirring to generate a metal composite hydroxide. The alkaline solution used here is preferably added dropwise in an amount sufficient for the aqueous solution b' to maintain pH 10-14. As such an alkaline solution, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, or the like can be used. Among them, it is preferable to use ammonia, sodium hydroxide, sodium carbonate, or a mixed solution thereof.

The temperature of the aqueous solution b' during the neutralization reaction is preferably 40°C or higher, more preferably 40°C to 60°C. The stirring time of the aqueous solution b' is preferably 30 minutes to 120 minutes, more preferably 30 minutes to 60 minutes.
In order to obtain a useful positive electrode active material, an oxidizing agent such as sodium hypochlorite or hydrogen peroxide solution is added to the aqueous solution b' after the neutralization reaction from the viewpoint of forming a metal composite hydroxide with a high bulk density. You may

After stirring, the metal composite hydroxide may be recovered by filtering the aqueous solution b'. The recovered metal composite hydroxide is preferably calcined to form a metal composite oxide from the viewpoint of stabilizing the quality of the obtained lithium composite oxide and from the viewpoint of uniform and sufficient reaction with lithium.
The firing conditions for obtaining the metal composite oxide from the metal composite hydroxide are not particularly limited. temperature.

Next, the metal composite oxide obtained by the above firing and the lithium compound are dry-mixed so as to obtain the desired composition of the lithium composite oxide, and the mixed powder thus obtained is fired in an oxygen atmosphere. Examples of the lithium compound used here include lithium hydroxide or its hydrate, lithium peroxide, lithium nitrate, and lithium carbonate. For the dry mixing of the metal composite oxide and the lithium compound, an ordinary dry mixer such as a ball mill or V-blender, or a mixing granulator or the like can be used. In addition, for firing, an electric furnace, rotary kiln, tubular furnace, pusher furnace, etc., in which the oxygen concentration in the gas atmosphere is adjusted to 20% by mass or more, such as an oxygen atmosphere, a dry air atmosphere that has been subjected to dehumidification and decarbonation treatment. can be used.

The sintering conditions for the mixed powder are selected from the viewpoint of avoiding structural instability due to undeveloped crystals of the resulting lithium composite oxide, and the collapse of the layered structure of the lithium composite oxide to produce lithium ions. From the viewpoint of avoiding difficulty in insertion and desorption, the firing temperature is preferably 650°C to 850°C, more preferably 700°C to 800°C. The firing time is preferably 5 hours to 20 hours, more preferably 6 hours to 10 hours.

Firing of the mixed powder is preferably carried out in two steps (temporary firing and final firing). By adopting two-stage firing, in the temporary firing, after removing thermally decomposed components such as water molecules and carbon dioxide from hydroxides and carbonates in the mixed powder, main firing is performed, which is efficient. NCA-based composite oxide secondary particles (A) can be obtained. As the conditions for calcination, it is preferable that the calcination temperature is 400° C. to 600° C. and the calcination time is 1 hour or more. The resulting granules are subjected to main firing. As conditions for the main firing, it is preferable that the firing temperature is 650° C. to 850° C. and the firing time is 5 hours or longer.

Finally, the fired product obtained by the main firing is washed with water, filtered and dried to obtain NCA-based composite oxide secondary particles (A). The slurry concentration when washing the fired product obtained in the main firing with water is 200 g/L to 4000 g/L from the viewpoint of suppressing the detachment of lithium from the resulting NCA-based composite oxide secondary particles (A). L is preferred, and 500 g/L to 2000 g/L is more preferred.
In addition, from the viewpoint of avoiding the deposition of lithium carbonate on the NCA-based composite oxide secondary particles (A) due to the large amount of carbon dioxide contained in the water, the electrical conductivity of the water used for washing is It is preferably less than 10 μS/cm, more preferably 1 μS/cm or less.
Furthermore, drying is preferably carried out in two stages. The first stage of drying is performed at 90° C. or less until the water content (moisture content measured at a vaporization temperature of 300° C.) in the secondary particles of lithium composite oxide becomes 1% by mass or less. After that, it is preferable to carry out the second stage drying at 120° C. or higher.

A positive electrode active material composite for a lithium ion secondary battery of the present invention is applied as a positive electrode material, and a lithium ion secondary battery containing the positive electrode active material composite includes a positive electrode, a negative electrode, an electrolyte solution and a separator, or a positive electrode, a negative electrode and a solid electrolyte. It is not particularly limited as long as it has a configuration.

Here, as for the negative electrode, as long as it can absorb lithium ions during charging and release lithium ions during discharging, the material composition is not particularly limited, and a known material composition can be used. For example, lithium metal, graphite, silicon-based (Si, SiO _x ), lithium titanate, carbon materials such as amorphous carbon, and the like can be used. It is preferable to use an electrode made of an intercalate material capable of electrochemically intercalating and deintercalating lithium ions, particularly a carbon material. Furthermore, two or more of the above negative electrode materials may be used in combination, for example, a combination of graphite and silicon can be used.

The electrolytic solution is obtained by dissolving a supporting salt in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is generally used in electrolytes for lithium ion secondary batteries. Examples include carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, Lactones, oxolane compounds and the like can be used.

The type of supporting salt is not particularly limited, but inorganic salts selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , derivatives of the inorganic salts, LiSO ₃ CF ₃ , LiC(SO ₃ CF ₃ ) ₂ and LiN(SO ₃ CF ₃ ) ₂ , LiN(SO ₂ C ₂ F ₅ ) ₂ and LiN(SO ₂ CF ₃ )(SO ₂ C ₄ F ₉ ), and derivatives of said organic salts. is preferably at least one of

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

The solid electrolyte electrically insulates the positive electrode and the negative electrode, exhibits high lithium ion conductivity, and may be the same as or different from the lithium-based solid electrolyte (D). _{For example , La0.51Li0.34TiO2.94 , Li1.3Al0.3Ti1.7 ( PO4 ) 3 , Li7La3Zr2O12 , Li3PO4 - Li4SiO4 , 50Li4SiO4.50Li3BO3 , _ Li2.9PO3.3N0.46 , Li3.6Si0.6P0.4O4 , Li1.07Al0.69Ti1.46 ( PO4 ) 3 , Li1.5Al0.5Ge1.5 ( PO4 ) 3 , Li10GeP2S12 , Li3.25Ge _ _ 0.25P0.75S4 , 30Li2S.26B2S3.44LiI , 63Li2S.36SiS2.1Li3PO4 , 57Li2S.38SiS2.5Li4SiO4 , 70Li2S.30P2S5 , _ _ _ _ _ _ _ 50Li2S.50GeS2 , Li7P3S11 , and Li3.25P0.95S4 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 shape, a cylindrical shape, a square shape, or an irregular shape enclosed in a laminated outer package. .

EXAMPLES The present invention will be specifically described below 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 drop rate of 300 ml/min to obtain a slurry A1 containing a metal composite hydroxide having a pH of 11.
Next, the slurry A1 was filtered and dried to obtain a mixture A2 of metal composite hydroxides, and then 37 g of lithium carbonate was mixed with the mixture A2 in a ball mill to obtain a powder mixture A3.
The obtained powder mixture A3 is preliminarily fired at 800 ° C. for 5 hours in an air atmosphere, crushed, and then granulated, and then fired at 800 ° C. for 10 hours in an air atmosphere as main firing to produce a lithium composite oxide. 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)]
370 g of lithium carbonate, 950 g of nickel carbonate, 150 g of cobalt carbonate, 58 g of aluminum carbonate, 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, they were mixed in a ball mill to obtain a powder mixture A4. The obtained powder mixture A4 is preliminarily fired at 800 ° C. for 5 hours in an air atmosphere and crushed, and then fired as main firing at 800 ° C. for 24 hours in an air atmosphere to produce 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 lithium-based polyanion particles (B-1)]
1272 g of LiOH.H ₂ O and 4 L of water were mixed to obtain slurry B1. Next, 1153 g of an 85% phosphoric acid aqueous solution was added dropwise to the obtained slurry B1 at a rate of 35 mL/min while stirring for 3 minutes while maintaining the temperature at 25° C., followed by cellulose nanofibers (Wma-10002, manufactured by Sugino Machine Co., Ltd.). (fiber diameter: 4 to 20 nm) was added and stirred at a speed of 400 rpm for 12 hours to obtain slurry B2 containing Li ₃ PO ₄ .
The resulting slurry B2 was purged with nitrogen to adjust the dissolved oxygen concentration of the slurry B2 to 0.5 mg/L, and then 1688 g of MnSO ₄ .5H ₂ O and 834 g of FeSO ₄ .7H ₂ O were added to the total amount of the slurry B2. to obtain a slurry B3. The molar ratio of added MnSO ₄ and FeSO ₄ (manganese compound:iron compound) was 70:30.
Then, the obtained slurry B3 was put into an autoclave and hydrothermally reacted at 170° C. for 1 hour. The pressure inside the autoclave was 0.8 MPa. After the hydrothermal reaction, the crystals produced were filtered and then washed with 12 parts by mass of water per 1 part by mass of the crystals. The washed crystals were lyophilized at −50° C. for 12 hours to obtain complex B4.
1000 g of the obtained composite B4 was taken, and 3.59 g of LiNO ₃ , 4.5 g of Al(NO ₃ ) ₃ .9H ₂ O, 12.92 g of TiCl ₄ , 11.76 g of H ₃ PO ₄ and 1 L of water were added. Further, 43.71 g of 28% aqueous ammonia was added as a pH adjuster to obtain slurry B5. The resulting slurry B5 was dispersed for 1 minute with an ultrasonic stirrer (T25, manufactured by IKA) to uniformly color the entire slurry, and then a spray dryer (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.) was used. Granules B6 were obtained by spray drying.
The obtained granules B6 were sintered at 700° C. for 1 hour in an argon-hydrogen atmosphere (hydrogen concentration 3%) to obtain 1.0% by mass of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ and 2.0% by mass. Lithium-based polyanion particles (B-1) supporting cellulose nanofiber-derived carbon in mass % (LiMn _0.7 Fe _0.3 PO ₄ , amount of lithium-based solid electrolyte supported=1.0% by mass, amount of carbon supported=2 .0 mass %, average particle size: 100 nm).

[Production Example 4: Production of lithium-based polyanion particles (B-2)]
In the lithium-based polyanion particles (B-1) of Production Example 3, the amount of LiNO ₃ added to 1000 g of the composite B4 obtained was changed from 3.59 g to 17.95 g, and the amount of Al(NO ₃ ) _{3.9H 2} O was increased. The added amount was changed from _4.5 g to 22.5 g, the added amount of _TiCl4 was changed from 12.92 g to 64.6 g, the added amount of _H3PO4 was changed from 11.76 g to 58.8 g, and the pH adjuster 28 5.0 wt _{% Li1.3Al0.3Ti1.7 (PO4)3 and 2.0} wt% Lithium-based polyanion particles (B-2) (LiMn _0.7 Fe _0.3 PO ₄ , amount of lithium-based solid electrolyte supported=5.0% by mass, amount of carbon supported=2.0 mass %, average particle size: 100 nm).

[Production Example 5: Production of lithium-based polyanion particles (B-3)]
In the lithium-based polyanion particles (B-1) of Production Example 3, the amount of LiNO ₃ added to 1000 g of the composite B4 obtained was changed from 3.59 g to 35.9 g, and the amount of Al(NO ₃ ) _{3.9H 2} O was changed. The added amount was changed from _4.5 g to 45 g, the added amount of _TiCl4 was changed from 12.92 g to 129.2 g, the added amount of _H3PO4 was changed from 11.76 g to 117.6 g, and the pH adjuster 28% ammonia was added. 10.0 _% by mass of _{Li1.3Al0.3Ti1.7} (PO4) ₃ and 2.0% by mass of cellulose in the same manner as in Production Example ₃ except that the amount of water added was changed from _43.71 g to 437.1 g. Nanofiber-derived carbon-supported lithium-based polyanion particles (B-3) (LiMn _0.7 Fe _0.3 PO ₄ , amount of lithium-based solid electrolyte supported = 10.0 mass%, amount of carbon supported = 2.0 mass% , average particle size: 100 nm).

[Production Example 6: Production of lithium-based polyanion particles (B-4)]
In the lithium-based polyanion particles (B-1) of Production Example 3, the amount of LiNO ₃ added to 1000 g of the composite B4 obtained was changed from 3.59 g to 53.85 g, and the amount of Al(NO ₃ ) _{3.9H 2} O was increased. The added amount was changed from _4.5 g to 67.5 g, the added amount of _TiCl4 was changed from 12.92 g to 193.8 g, the added amount of _H3PO4 was changed from 11.76 g to 176.4 g, and the pH adjuster 28 15.0 wt _{% Li1.3Al0.3Ti1.7 (PO4)3 and 2.0} wt% Lithium-based polyanion particles (B-4) (LiMn _0.7 Fe _0.3 PO ₄ , supported amount of lithium-based solid electrolyte = 15.0 mass%, supported amount of carbon = 2.0 mass %, average particle size: 100 nm).

[Production Example 7: Production of lithium-based polyanion particles (B-5)]
In the lithium-based polyanion particles (B-1) of Production Example 3, the amount of LiNO ₃ added to 1000 g of the composite B4 obtained was changed from 3.59 g to 71.8 g, and the amount of Al(NO ₃ ) _{3.9H 2} O was changed. The added amount was changed from _4.5 g to 90 g, the added amount of _TiCl4 was changed from 12.92 g to 258.4 g, the added amount of _H3PO4 was changed from 11.76 g to 235.2 g, and the pH adjuster 28% ammonia was added. 20.0 _% by mass of _{Li1.3Al0.3Ti1.7} (PO4) ₃ and 2.0% by mass of cellulose in the same manner as in Production Example ₃ except that the amount of water added was changed from _43.71 g to 874.2 g. Nanofiber-derived carbon-supported lithium-based polyanion particles (B-5) (LiMn _0.7 Fe _0.3 PO ₄ , amount of lithium-based solid electrolyte supported = 20.0% by mass, amount of carbon supported = 2.0% by mass , average particle size: 100 nm).

[Production Example 8: Production of lithium-based polyanion particles (B-6)]
In the lithium-based polyanion particles (B-1) of Production Example 3, 2.0% by mass of carbon derived from cellulose nanofibers was added in the same manner as in Production Example 3, except that only 1 L of water was added to the resulting composite B4. Lithium-based polyanion particles (B-6) (LiMn _0.7 Fe _0.3 PO ₄ , supported amount of lithium-based solid electrolyte = 0.0 mass%, supported amount of carbon = 2.0 mass%, average particle size : 100 nm).

[Production Example 9: Production of lithium-based polyanion particles (B-7)]
In the lithium-based polyanion particles (B-1) of Production Example 3, the amount of cellulose nanofibers added to slurry B1 was changed from 5892 g to 35352 g, and only 1 L of water was added to composite B4 obtained. 3, lithium-based polyanion particles (B-7) (LiMn _0.7 Fe _0.3 PO ₄ , supported amount of lithium-based solid electrolyte=0.0% by mass) supporting only cellulose nanofiber-derived carbon. 0% by mass, amount of carbon supported=12.0% by mass, average particle size: 100 nm).

[Production Example 10: Production of lithium-based polyanion particles (C-1)]
428 g of LiOH·H ₂ O, 1397 g of Na ₄ SiO ₄ ·nH ₂ O, 2946 g of cellulose nanofiber (same as above), and 3.75 L of water were mixed to obtain slurry C1. Next, 793 g of MnSO ₄ .5H ₂ O, 392 g of FeSO ₄ .7H ₂ O, and 53 g of Zr(SO ₄ ) ₂ .4H ₂ O were added to the obtained slurry C1 and mixed to obtain a slurry C2. At this time, the molar ratio of FeSO ₄ , MnSO ₄ and Zr(SO ₄ ) ₂ added (iron compound:manganese compound:zirconium compound) was 28:66:3.
Next, the obtained slurry C2 was put into an autoclave and hydrothermally reacted at 170° C. for 3 hours. The pressure inside the autoclave was 0.4 MPa. After the hydrothermal reaction, the crystals produced were filtered and then washed with 12 parts by mass of water per 1 part by mass of the crystals. The washed crystals were lyophilized at −50° C. for 12 hours to obtain complex C3.
500 g of the obtained composite C3 was taken and mixed with 1.80 g of LiNO ₃ , 2.25 g of Al(NO ₃ ) ₃ .9H ₂ O, 6.46 g of TiCl ₄ , 5.88 g of H ₃ PO ₄ and 0.8 g of water. 5 L was added, and 21.86 g of 28% aqueous ammonia was added as a pH adjuster to obtain slurry C4. The resulting slurry C4 was dispersed for 1 minute with an ultrasonic stirrer (same as above) to uniformly color the whole, and then spray-dried using a spray dryer (same as above) to obtain granules C5. Obtained.
The resulting granules C5 were fired at 650° C. for 1 hour in an argon-hydrogen atmosphere (hydrogen concentration 3%) to obtain 1.0% by mass of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ and 2.0% by mass. Lithium-based polyanion particles (C-1) supporting cellulose nanofiber-derived carbon in an amount of 1% by mass (Li ₂ Mn _0.66 Fe _0.28 Zr _0.03 SiO ₄ , supported amount of lithium-based solid electrolyte = 1.0% by mass, supported amount = 2.0% by mass, average particle size: 50 nm).

[Production Example 11: Production of lithium-based polyanion particles (C-2)]
In the lithium-based polyanion particles (C-1) of Production Example 10, the amount of LiNO added to 500 g of the obtained composite C3 was changed from 1.80 g to 8.98 g, and the amount of Al _{(NO 3 ) 3.9H 2 O was increased} . The added amount was changed from 2.25 g to 11.25 g, the added amount of _TiCl4 was changed from 6.46 g to 32.3 g, the added amount of _H3PO4 was changed from _5.88 g to 29.4 g, and the pH adjuster 28 5.0 wt _{% Li1.3Al0.3Ti1.7 (PO4)3 and 2.0} wt% Lithium-based polyanion particles (C-2) (Li ₂ Mn _0.66 Fe _0.28 Zr _0.03 SiO ₄ , supported amount of lithium-based solid electrolyte = 5.0 mass%, supported amount of carbon = 2.0% by mass, average particle size: 50 nm).

[Production Example 12: Production of lithium-based polyanion particles (C-3)]
In the lithium-based polyanion particles (C-1) of Production Example 10, the amount of LiNO added to 500 g of the composite C3 obtained was changed from 1.80 g to 18.0 g, and the amount of Al _{(NO 3 ) 3.9H 2 O was increased} . The added amount was changed from 2.25 g to 22.5 g, the added amount of _TiCl4 was changed from 6.46 g to _64.6 g, the added amount of _H3PO4 was changed from 5.88 g to 58.8 g, and the pH adjuster 28 10.0 wt _{% Li1.3Al0.3Ti1.7 (PO4)3 and 2.0} wt% Lithium-based polyanion particles (C-3) (Li ₂ Mn _0.66 Fe _0.28 Zr _0.03 SiO ₄ , supported amount of lithium-based solid electrolyte = 10.0% by mass, supported amount of carbon derived from cellulose nanofibers) = 2.0% by mass, average particle size: 50 nm).

[Production Example 13: Production of lithium-based polyanion particles (C-4)]
In the lithium-based polyanion particles (C-1) of Production Example 10, the amount of LiNO added to 500 g of the composite C3 obtained was changed from 1.80 g to 26.9 g, and the amount of Al _{(NO 3 ) 3.9H 2 O was increased} . The added amount was changed from 2.25 g to 33.8 g, the added amount of TiCl ₄ was changed from 6.46 g to 96.9 g, the added amount of H ₃ PO ₄ was changed from 5.88 g to 88.2 g, and the pH adjuster 28 15.0 wt _{% Li1.3Al0.3Ti1.7 (PO4)3 and 2.0} wt% Lithium-based polyanion particles (C-4) (Li ₂ Mn _0.66 Fe _0.28 Zr _0.03 SiO ₄ , supported amount of lithium-based solid electrolyte = 15.0% by mass, supported amount of carbon derived from cellulose nanofibers) = 2.0% by mass, average particle size: 50 nm).

[Production Example 14: Production of lithium-based polyanion particles (C-5)]
In the lithium-based polyanion particles (C-1) of Production Example 10, the amount of LiNO added to 500 g of the composite C3 obtained was changed from 1.80 g to 35.9 g, and the amount of Al _{(NO 3 ) 3.9H 2 O was increased} . The added amount was changed from 2.25 g to 45.0 g, the added amount of _TiCl4 was changed from 6.46 g to _129.2 g, the added amount of _H3PO4 was changed from 5.88 g to 117.6 g, and the pH adjuster 28 20.0 wt _{% Li1.3Al0.3Ti1.7 (PO4)3 and 2.0} wt% Lithium-based polyanion particles (C-5) (Li ₂ Mn _0.66 Fe _0.28 Zr _0.03 SiO ₄ , supported amount of lithium-based solid electrolyte = 20.0% by mass, supported amount of carbon derived from cellulose nanofibers) = 2.0% by mass, average particle size: 50 nm).

[Production Example 15: Production of lithium-based polyanion particles (C-6)]
2.0% by mass of cellulose nanofiber-derived Lithium-based polyanion particles (C-6) (Li ₂ Mn _0.66 Fe _0.28 Zr _0.03 SiO ₄ , supported amount of lithium-based solid electrolyte = 0.0 mass%, supported amount of carbon = 2.0 mass %, average particle size: 50 nm).

[Production Example 16: Production of lithium-based polyanion particles (C-7)]
In the lithium-based polyanion particles (C-1) of Production Example 10, the content of cellulose nanofibers in the slurry C1 was changed from 2946 g to 17676 g, and only 1 L of water was added to the resulting composite C3. 10, lithium-based polyanion particles (C-7) (Li ₂ Mn _0.66 Fe _0.28 Zr _0.03 SiO ₄ , supporting only 12.0% by mass of cellulose nanofiber-derived carbon, supporting lithium-based solid electrolyte amount = 0.0% by mass, amount of carbon supported = 12.0% by mass, average particle diameter: 50 nm).

[Example 1: Secondary particles of lithium composite oxide (A-1) + lithium-based polyanion particles (B-1)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1 and 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were mixed with Mechanofusion (manufactured by Hosokawa Micron Corporation, AMS- Lab) for 10 minutes at 2600 rpm (20 m / sec), and the surface of the NCM-based composite oxide secondary particles (A) is treated with 1% by mass of lithium solid electrolyte and 2% by mass of carbon. Positive electrode active material composite for lithium ion secondary battery (P-1) supporting lithium-based polyanion particles (B) supported by (secondary particles (A): particles (B) = 60: 40 (mass ratio ), an average particle size of 13 μm, and a tap density of 1.4 g/cm ³ ).

[Example 2: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-2)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (B-2) obtained in Production Example 4. The surface of the system composite oxide secondary particles (A) is supported by lithium-based polyanion particles (B) in which 5% by mass of lithium solid electrolyte and 2% by mass of carbon are supported. Positive electrode active for lithium ion secondary batteries A substance composite (P-2) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 3: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-3)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (B-3) obtained in Production Example 5. Lithium-based polyanion particles (B) supporting 10% by mass of lithium solid electrolyte and 2% by mass of carbon on the surface of secondary composite oxide particles (A). Positive electrode active for lithium ion secondary batteries. A substance composite (P-3) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 4: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-1)]
Example 1 except that 300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1 were changed to 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2. In the same manner as above, the surfaces of the NCA-based composite oxide secondary particles (A) were coated with 1% by mass of lithium solid electrolyte and 2% by mass of carbon-supported lithium-based polyanion particles (B). A positive electrode active material composite (P-4) for a secondary battery (secondary particles (A): particles (B) = 60:40 (mass ratio), average particle diameter 13 µm, tap density 1.4 g/cm ³ ) was prepared. Obtained.

[Example 5: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-2)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (B-2) obtained in Production Example 4. A positive electrode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) supporting 5% by mass of a lithium solid electrolyte and 2% by mass of carbon ( P-5) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 6: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-3)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (B-3) obtained in Production Example 5. A positive electrode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) in which 10% by mass of a lithium solid electrolyte and 2% by mass of carbon are supported ( P-6) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 1: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-6)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (B-6) obtained in Production Example 8. A positive electrode active material composite for a lithium ion secondary battery in which the surface of the system composite oxide secondary particles (A) is supported by lithium-based polyanion particles (B) in which only 2% by mass of carbon is supported (P-7 ) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ).

[Comparative Example 2: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-7)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (B-7) obtained in Production Example 9. A positive electrode active material composite for a lithium ion secondary battery in which the surface of the system composite oxide secondary particles (A) is supported by lithium-based polyanion particles (B) in which only 12% by mass of carbon is supported (P-8 ) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ).

[Comparative Example 3: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-4)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (B-4) obtained in Production Example 6. Lithium-based polyanion particles (B) supporting 15% by mass of lithium solid electrolyte and 2% by mass of carbon are supported on the surface of secondary composite oxide particles (A). Positive electrode active for lithium ion secondary batteries. A substance composite (P-9) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 4: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-5)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (B-5) obtained in Production Example 7. Lithium-based polyanion particles (B) supporting 20% by mass of lithium solid electrolyte and 2% by mass of carbon on the surface of secondary composite oxide particles (A). Positive electrode active for lithium ion secondary batteries. A substance composite (P-10) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 5: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-6)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 An NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (B-6) obtained in Production Example 8. A positive electrode active material composite (P-11) (secondary Particles (A): Particles (B) = 60:40 (mass ratio), average particle diameter 13 µm, tap density 1.4 g/cm ³ ).

[Comparative Example 6: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-7)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (B-7) obtained in Production Example 9. The surface of the secondary particles (A) is a positive electrode active material composite (P-12) for a lithium ion secondary battery in which lithium-based polyanion particles (B) in which only 12% by mass of carbon is supported is supported (secondary Particles (A): Particles (B) = 60:40 (mass ratio), average particle diameter 13 µm, tap density 1.4 g/cm ³ ).

[Comparative Example 7: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-4)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (B-4) obtained in Production Example 6. A cathode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) supporting 15% by mass of a lithium solid electrolyte and 2% by mass of carbon ( P-13) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 8: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-5)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (B-5) obtained in Production Example 7. A positive electrode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) supporting 20% by mass of a lithium solid electrolyte and 2% by mass of carbon ( P-14) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 7: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-1)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (C-1) obtained in Production Example 10. Lithium-based polyanion particles (B) supporting 1% by mass of lithium solid electrolyte and 2% by mass of carbon on the surface of secondary composite oxide particles (A). Positive electrode active for lithium ion secondary batteries. A substance composite (S-1) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 8: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-2)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (C-2) obtained in Production Example 11. The surface of the system composite oxide secondary particles (A) is supported by lithium-based polyanion particles (B) in which 5% by mass of lithium solid electrolyte and 2% by mass of carbon are supported. Positive electrode active for lithium ion secondary batteries A substance composite (S-2) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 9: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-3)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (C-3) obtained in Production Example 12. Lithium-based polyanion particles (B) supporting 10% by mass of lithium solid electrolyte and 2% by mass of carbon on the surface of secondary composite oxide particles (A). Positive electrode active for lithium ion secondary batteries. A substance composite (S-3) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 10: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-1)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1 were changed to 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (C-1) obtained in Production Example 10. A positive electrode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) supporting 1% by mass of a lithium solid electrolyte and 2% by mass of carbon ( S-4) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 11: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-2)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (C-2) obtained in Production Example 11. A positive electrode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) supporting 5% by mass of a lithium solid electrolyte and 2% by mass of carbon ( S-5) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 12: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-3)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (C-3) obtained in Production Example 12. A positive electrode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) in which 10% by mass of a lithium solid electrolyte and 2% by mass of carbon are supported ( S-6) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 9: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-6)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (C-6) obtained in Production Example 15. A positive electrode active material composite for a lithium ion secondary battery in which the surface of the system composite oxide secondary particles (A) is supported by lithium-based polyanion particles (B) in which only 2% by mass of carbon is supported (S-7 ) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ).

[Comparative Example 10: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-7)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (C-7) obtained in Production Example 16. A positive electrode active material composite for a lithium ion secondary battery in which the surface of the system composite oxide secondary particles (A) is supported by lithium-based polyanion particles (B) in which only 12% by mass of carbon is supported (S-8 ) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ).

[Comparative Example 11: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-4)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (C-4) obtained in Production Example 13. Lithium-based polyanion particles (B) supporting 15% by mass of lithium solid electrolyte and 2% by mass of carbon on the surface of secondary composite oxide particles (A). Positive electrode active for lithium ion secondary batteries. A substance composite (S-9) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 12: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-5)]
NCM in the same manner as in Example 1, except that 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 200 g of the lithium-based polyanion particles (C-5) obtained in Production Example 14. Lithium-based polyanion particles (B) supporting 20% by mass of lithium solid electrolyte and 2% by mass of carbon on the surface of secondary composite oxide particles (A). Positive electrode active for lithium ion secondary batteries. A substance composite (S-10) (secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 13: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-6)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (C-6) obtained in Production Example 15. A positive electrode active material composite (S-11) (secondary Particles (A): Particles (B) = 60:40 (mass ratio), average particle diameter 13 µm, tap density 1.4 g/cm ³ ).

[Comparative Example 14: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-7)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (C-7) obtained in Production Example 16. The surface of the secondary particles (A) is coated with a lithium-based polyanion particle (B) in which only 12% by mass of carbon is supported. Particles (A): Particles (B) = 60:40 (mass ratio), average particle diameter 13 µm, tap density 1.4 g/cm ³ ).

[Comparative Example 15: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-4)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 An NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (C-4) obtained in Production Example 13. A cathode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) supporting 15% by mass of a lithium solid electrolyte and 2% by mass of carbon ( S-13) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Comparative Example 16: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-5)]
300 g of the lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2, and further in Production Example 3 NCA-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of the obtained lithium-based polyanion particles (B-1) were changed to 200 g of the lithium-based polyanion particles (C-5) obtained in Production Example 14. A positive electrode active material composite for a lithium ion secondary battery in which the surfaces of the secondary particles (A) are supported by lithium-based polyanion particles (B) supporting 20% by mass of a lithium solid electrolyte and 2% by mass of carbon ( S-14) (Secondary particles (A):particles (B)=60:40 (mass ratio), average particle diameter 13 μm, tap density 1.4 g/cm ³ ) was obtained.

[Example 101: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-1)]
In Example 4, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (B-1) obtained in Production Example 3 were changed to 50 g. In the same manner as in Example 4, except that the surface of the NCA-based composite oxide secondary particles (A) was coated with 1% by mass of lithium solid electrolyte and 2% by mass of carbon-supported lithium-based polyanion particles (B) Positive electrode active material composite for lithium ion secondary battery (P-101) (secondary particle (A): particle (B) = 90: 10 (mass ratio), average particle diameter 11.5 μm, tap density 1.6 g/cm ³ ).

[Example 102: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-2)]
In Example 5, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (B-2) obtained in Production Example 4 were changed to 50 g. In the same manner as in Example 5 except that the surfaces of the NCA-based composite oxide secondary particles (A) were coated with 5% by mass of lithium solid electrolyte and 2% by mass of carbon-supported lithium-based polyanion particles (B) Positive electrode active material composite for lithium ion secondary battery (P-102) (secondary particle (A): particle (B) = 90: 10 (mass ratio), average particle diameter 11.5 μm, tap density 1.6 g/cm ³ ).

[Example 103: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-3)]
In Example 6, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (B-3) obtained in Production Example 5 were changed to 50 g. In the same manner as in Example 6, except that the surface of the NCA-based composite oxide secondary particles (A) was coated with 10% by mass of lithium solid electrolyte and 2% by mass of carbon-supported lithium-based polyanion particles (B) Positive electrode active material composite for lithium ion secondary battery (P-103) (secondary particle (A): particle (B) = 90: 10 (mass ratio), average particle diameter 11.5 μm, tap density 1.6 g/cm ³ ).

[Comparative Example 101: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (B-6)]
In Comparative Example 5, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (B-6) obtained in Production Example 8 were changed to 50 g. In the same manner as in Comparative Example 5, except that the surfaces of the NCA-based composite oxide secondary particles (A) were coated with lithium-ion divalent particles supporting lithium-based polyanion particles (B) supporting only 2% by mass of carbon. Positive electrode active material composite for next battery (P-104) (secondary particles (A): particles (B) = 90:10 (mass ratio), average particle diameter 11.5 µm, tap density 1.6 g/cm ³ ) got

[Comparative Example 102: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (B-7)]
In Comparative Example 6, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (B-7) obtained in Production Example 9 were changed to 50 g. In the same manner as in Comparative Example 6, except that the surface of the NCA-based composite oxide secondary particles (A) was coated with lithium-ion divalent particles supporting only 12% by mass of carbon-supported lithium-based polyanion particles (B). Positive electrode active material composite for next battery (P-105) (secondary particles (A): particles (B) = 90:10 (mass ratio), average particle diameter 11.5 µm, tap density 1.6 g/cm ³ ) got

[Example 104: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-1)]
In Example 10, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (C-1) obtained in Production Example 10 were changed to 50 g. In the same manner as in Example 10, except that the surface of the NCA-based composite oxide secondary particles (A) was coated with 1% by mass of lithium solid electrolyte and 2% by mass of carbon-supported lithium-based polyanion particles (B) Positive electrode active material composite for lithium ion secondary battery (S-101) (secondary particle (A): particle (B) = 90: 10 (mass ratio), average particle diameter 11.5 μm, tap density 1.6 g/cm ³ ).

[Example 105: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-2)]
In Example 11, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (C-2) obtained in Production Example 11 were changed to 50 g. In the same manner as in Example 11, except that the surface of the NCA-based composite oxide secondary particles (A) was coated with 5% by mass of lithium solid electrolyte and 2% by mass of carbon-supported lithium-based polyanion particles (B) Positive electrode active material composite for lithium ion secondary batteries (S-102) (secondary particles (A): particles (B) = 90: 10 (mass ratio), average particle diameter 11.5 μm, tap density 1.6 g/cm ³ ).

[Example 106: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-3)]
In Example 12, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (C-3) obtained in Production Example 12 were changed to 50 g. In the same manner as in Example 12, except that the surface of the NCA-based composite oxide secondary particles (A) was coated with 10% by mass of lithium solid electrolyte and 2% by mass of carbon-supported lithium-based polyanion particles (B) Positive electrode active material composite for lithium ion secondary batteries (S-103) (secondary particles (A): particles (B) = 90: 10 (mass ratio), average particle diameter 11.5 μm, tap density 1.6 g/cm ³ ).

[Comparative Example 103: Lithium composite oxide secondary particles (A-2) + lithium-based polyanion particles (C-6)]
In Comparative Example 13, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (C-6) obtained in Production Example 15 were changed to 50 g. In the same manner as in Comparative Example 13, except that the surfaces of the NCA-based composite oxide secondary particles (A) were coated with lithium-based polyanion particles (B) supporting only 2% by mass of carbon, lithium ion divalent Positive electrode active material composite for next battery (S-104) (secondary particles (A): particles (B) = 90:10 (mass ratio), average particle diameter 11.5 µm, tap density 1.6 g/cm ³ ) got

[Comparative Example 104: Lithium composite oxide secondary particles (A-1) + lithium-based polyanion particles (C-7)]
In Comparative Example 14, 300 g of the lithium composite oxide secondary particles (A-2) obtained in Production Example 2 were changed to 450 g, and 200 g of the lithium-based polyanion particles (C-7) obtained in Production Example 16 were changed to 50 g. In the same manner as in Comparative Example 14, except that the surface of the NCA-based composite oxide secondary particles (A) was coated with lithium-ion divalent particles supporting only 12% by mass of carbon-supported lithium-based polyanion particles (B). Positive electrode active material composite for next battery (S-105) (secondary particles (A): particles (B) = 90:10 (mass ratio), average particle diameter 11.5 µm, tap density 1.6 g/cm ³ ) got

《Measurement of adsorbed water content》
For all the positive electrode active material composites for lithium ion secondary batteries obtained in Examples 1 to 12, 101 to 106 and Comparative Examples 1 to 16, 101 to 104, the temperature was 20 ° C. and the relative humidity was 50%. After standing for a day to adsorb moisture until equilibrium is reached, the temperature was raised to 150 ° C. and held for 20 minutes, and then the temperature was further raised to 250 ° C. and held for 20 minutes. The amount of volatilized water was measured with a Karl Fischer moisture meter (MKC-610, manufactured by Kyoto Electronics Industry Co., Ltd.) from the time when the temperature was stopped to the end point when the constant temperature condition at 250° C. was finished.
Tables 1 and 2 show the measurement results together with the evaluation results of the rate characteristics.

《Evaluation of rate characteristics》
Using all the positive electrode active material composites for lithium ion secondary batteries obtained in Examples 1 to 12, 101 to 106 and Comparative Examples 1 to 16, 101 to 104 as positive electrode materials, positive electrodes of lithium ion secondary batteries were used. made. Specifically, the obtained positive electrode active material composite for lithium ion secondary batteries, Ketjenblack, and polyvinylidene fluoride were mixed at a mass ratio of 90:5:5, and N-methyl-2 -Pyrrolidone was added and thoroughly kneaded 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. After that, it was punched into a disk shape of φ14 mm and pressed at 16 MPa for 2 minutes using a hand press to obtain a positive electrode.
Next, a coin-type secondary battery was constructed using the above positive electrode. A lithium foil punched into a diameter of φ15 mm was used as the negative electrode. The electrolytic solution used was obtained by dissolving LiPF ₆ at a concentration of 1 mol/L in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 3:7. A polymer porous film was used as the separator. These battery parts were incorporated and housed in an atmosphere with a dew point of -50°C or less by a conventional method 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 at a current of 34 mA / g and a voltage of 4.25 V, constant current discharging at a current of 34 mA / g and a final voltage of 3.0 V is performed, and the discharge capacity at a current density of 34 mA / g (0.2 C) is asked. Further, constant-current charging was performed under the same conditions, and constant-current discharging was performed at 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 conducted at 30°C.
The results are shown in Tables 1 and 2 together with the measurement results of the amount of adsorbed water.
Also, from the obtained discharge capacity, the discharge capacity ratio (%) was determined by the following formula (x). The results are shown in Tables 1-2.
Discharge capacity ratio (%) = (discharge capacity at 3C) /
(Discharge capacity at 0.2C) x 100 (x)

From the results in Tables 1 and 2, it can be seen that in the examples, the water adsorption amount was effectively reduced, and good discharge capacity and rate characteristics (discharge capacity ratio) were exhibited.
On the other hand, in Comparative Examples 1, 2, 5, 6, 9, 10, 13, 14, 101, 102, 103, and 104, the lithium-based polyanion particles (B) only support carbon (C). , it can be seen that the water adsorption amount is high in all of them, and at least one of the discharge capacity and the rate characteristics is lower than those of the examples. In Comparative Examples 3, 4, 7, 8, 11, 12, 15, and 16, the lithium-based polyanion particles (B) carried an excessive amount of the lithium solid electrolyte (D). is reduced to the same extent as in Examples, the electronic conductivity of the lithium-based polyanion particles (B) is lowered, resulting in a low discharge capacity.

Claims (7)

Formula (1) or (2) below:
_{LiNiaCobMncM1wO2 (} ¹ _{) _ _}
(In 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, one or more elements selected from Bi and Ge, where a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, 0≦w≦0.3 and 3a+3b+3c+(valence of M1)×w= ³ .)
_{LiNidCoeAlfM2xO2 (} ² _{) _ _}
(In formula ( ² ), M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and one or more elements selected from Ge, d, e, f, and x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ A number that satisfies ^x≤0.3 and 3d+3e+3f+(valence of M2)×x=3.)
On the surface of the lithium composite oxide secondary particles (A) made of lithium composite oxide particles represented by the following formula (3) or (4):
_{LigMnhFeiM3yPO4 (} ³ _{) _ _}
(In formula ( ³ ), M3 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. g, h, i, and y are 0 < g ≤ 1.2, 0.3 ≤ h ≤ 1, 0 ≤ i ≤ 0.7, and 0 ≤ y ≤ 0.3, and g + (valence of Mn) × h + (valence of Fe ) x i + (valence of M3) x y = ^3. )
_{LijMnkFe1M4zSiO4 (} ⁴ _{) _ _}
(In formula ( ⁴ ), M4 represents Co, Ni, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, Al, Zn, V or Gd. j, k, l and z satisfy 0 < j ≤ 2.4, 0 ≤ k ≤ 1.2, 0 ≤ l ≤ 1.2, 0 ≤ z ≤ 1.2, and k + l ≠ 0, and j + (Mn valence) x k + (valence of Fe) x l + (valence of M4) x z = ^4. )
The lithium-based polyanion particles (B) represented by are supported, and the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface of the lithium-based polyanion particles (B),
The mass ratio ((D):(C)) of the supported amount of the lithium-based solid electrolyte (D) and the supported amount of carbon (C) on the surfaces of the lithium-based polyanion particles (B) is 1:5 to 7:1. A positive electrode active material composite for a lithium ion secondary battery. The carbon (C) supported on the surface of the lithium-based polyanion particles (B) includes carbon derived from cellulose nanofibers (C1), carbon derived from lignocellulose nanofibers (C2), and carbon derived from water-soluble carbon materials (C3 ), and a water-insoluble carbon material (C4). The lithium ion secondary according to claim 1 or 2, wherein the lithium-based solid electrolyte (D) is 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 A positive electrode active material composite for batteries. The mass ratio of the content of the lithium composite oxide secondary particles (A) to the content of the lithium-based polyanion particles (B) in which the lithium-based solid electrolyte (D) and carbon (C) are supported on the surface (( The positive electrode active material composite for a lithium ion secondary battery according to any one of claims 1 to 3, wherein A):(B)) is 95:5 to 55:45. The following steps (I)-(IV):
(I) a step of preparing a slurry containing a lithium compound, a metal compound containing at least an iron compound or a manganese compound, a phosphoric acid compound or a silicate compound, and then subjecting it to a hydrothermal reaction to obtain lithium-based polyanion primary particles;
(II) After preparing a slurry having a solid content concentration of 10% by mass to 35% by mass containing the obtained lithium-based polyanion primary particles and the raw material compound of the lithium-based solid electrolyte (D), the hot air supply amount G ( L/min) to the slurry (b-5) supply amount S (L/min) ratio (G/S) of 500 to 10000 to obtain granules by spray drying;
(III) A step of calcining the obtained granules at 500° C. to 800° C. for 10 minutes to 3 hours to obtain a pre-granulated product (b) having a porosity of 45% to 80% by volume, and ( IV) The obtained preliminary granules (b) and the lithium composite oxide secondary particles (A) are mixed while applying a compressive force and a shearing force to disintegrate the preliminary granules (b), A step of supporting the lithium-based solid electrolyte (D) and carbon (C) on the surface of the lithium-based polyanion particles (B) and compounding the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B). with
Either the slurry prepared in step (I) or the slurry prepared in step (II) is a slurry to which a carbon source (C') is further added, or A water-insoluble carbon material (C4) is added together with the particles (b) and the lithium composite oxide secondary particles (A), and mixed while applying compressive force and shear force. 3. The method for producing the positive electrode active material composite for a lithium ion secondary battery according to 1. The method for producing a positive electrode active material composite for a lithium ion secondary battery according to claim _{5 ,} wherein the lithium-based solid electrolyte (D) is _{Li1.3Al0.3Ti1.7} ( _PO4 ) ₃ . 7. The method for producing a positive electrode active material composite for a lithium ion secondary battery according to claim 5 or 6, wherein the sintering in step (III) is performed in a reducing gas atmosphere or an inert gas atmosphere.