JP2011113783A - Positive electrode active material for nonaqueous electrolyte battery, nonaqueous electrolyte battery, high-output electronic equipment, and automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive electrode active material for a nonaqueous electrolyte secondary battery with high energy density achieved and having high cycle characteristics, to provide a nonaqueous electrolyte secondary battery, to provide high-output electronic equipment using the battery, and to provide an automobile. <P>SOLUTION: A first positive electrode active material consisting of an olivine compound with an average particle diameter D1, and a second positive electrode active material consisting of an oxide with an average particle diameter D2 are used as a mixture, with an average particle diameter D1 of the olivine compound to be 8 μm or less, and a particle diameter ratio D2/D1 of the average particle diameter D2 of the olivine compound to the average particle diameter D1 of the oxide to be 1.5 or more. The first positive electrode active material is preferred to be secondary particles made by assembling a plurality of primary particles of the olivine compound, and preferably consists of secondary particles with an electron conductive substance intervened between primary particles. At this time, an average particle diameter of the primary particles is preferably to be 10 μm or more, and 600 μm or less, with an amount of mixed volume of the first positive electrode active material preferred to be 15 wt.% or more, and 70 wt.% or less, and an amount of mixed volume of the second positive electrode active material to be 30 wt.% or more, and 85 wt.% or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a positive electrode using a lithium composite oxide as a positive electrode active material and a non-aqueous electrolyte battery.

In recent years, with the widespread use of portable devices such as video cameras, mobile phones, and notebook computers, there is an increasing demand for secondary batteries that are small, lightweight, and high capacity as power sources. As a positive electrode active material constituting the secondary battery to meet such a demand, other lithium cobalt oxide (LiCoO _2), lithium nickel oxide having the same space group R3m / layered structure as lithium cobaltate (LiCoO ₂₎ (LiNiO ₂ ), Lithium manganate (LiMn ₂ O ₄ ) having a positive spinel structure and having a space group Fd3m has been put into practical use.

  In such lithium nickelate, the discharge capacity of lithium cobaltate is about 150 mAh / g, whereas a discharge capacity of about 180 to 200 mAh / g is obtained. In addition, since nickel (Ni), which is a raw material of lithium nickelate, is cheaper than cobalt (Co), lithium nickelate is superior to lithium cobaltate in terms of cost. Furthermore, nickel has better raw material supply stability than cobalt. For this reason, lithium nickelate is superior in terms of supply stability of raw materials.

  However, although the positive electrode active material using lithium nickelate has the advantages of large theoretical capacity and high discharge potential, the crystal structure of lithium nickelate collapses as the charge / discharge cycle is repeated. End up. As a result, in the battery using lithium nickelate as the positive electrode active material, problems such as a decrease in discharge capacity and deterioration in thermal stability have occurred.

Therefore, a lithium battery using a phosphate compound of a transition metal such as iron (Fe), manganese (Mn), cobalt (Co) and nickel (Ni) as a positive electrode active material has been proposed. This positive electrode active material has an olivine type crystal structure. As the phosphate compound having an olivine type crystal structure, for example, lithium iron phosphate using iron (Fe), which is a resource-rich and inexpensive metal ( LiFePO ₄ ). For example, as shown in Patent Document 1 below, a lithium battery using lithium iron phosphate (LiFePO ₄ ) as a positive electrode active material has been proposed.

  When these olivine compounds are used as a positive electrode active material of a secondary battery, they have excellent cycle characteristics because of little change in crystal structure accompanying charge / discharge. In addition, since oxygen atoms in the crystal are stably present due to covalent bonds with phosphorus (P), there is a merit that the possibility of oxygen release is small and the safety is excellent even when the battery is exposed to a high temperature environment. .

However, while the olivine compound has the advantages as described above, it has a drawback of low energy density. That is, the discharge capacity per weight is generally about 150 mAh / g for lithium cobaltate and about 180 to 200 mAh / g for lithium nickelate, which are generally used for lithium ion secondary batteries. On the other hand, the discharge capacity per weight of the olivine compound is at most equivalent to that of lithium cobaltate even if it has a high charge / discharge capacity. Furthermore, the true density of the material is 5.1 g / cm ³ for lithium cobaltate and 4.8 g / cm ³ for lithium nickelate, whereas the true density of the olivine compound is about 3.5 g / cm ³ . About 30% lower.

  For this reason, when an olivine compound is used alone as the positive electrode active material, the energy density per volume of the battery is lowered. In addition, since the olivine compound has a drawback of low electronic conductivity, when the olivine compound is used alone, there is a problem that load characteristics are inferior to lithium cobaltate and lithium nickelate.

In order to solve such problems, Patent Document 2 describes LiFePO ₄ or LiFe _0.4 Mn _0.6 PO ₄ and LiMO ₂ (where M is at least one of Co and Ni) or LiMn ₂ O _4. It is described that a positive electrode active material mixed with is used.

JP-A-9-134724 Japanese Patent No. 3959929

  In the above-mentioned Patent Document 2, it is proposed to construct a lithium-ion battery that is lower in cost than conventional ones, while minimizing discontinuous voltage changes during overdischarge and charge / discharge, and to ensure stable charge / discharge characteristics. Has been. However, no specific means for increasing the energy density is shown.

  Therefore, in view of the above-described problems, the present invention realizes a high energy density and has a high cycle characteristic, a positive electrode active material for a nonaqueous electrolyte secondary battery, a nonaqueous electrolyte secondary battery, and the same The purpose is to provide high-power electronic devices and automobiles.

In order to solve the above-described problem, the first invention includes a first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and an average particle diameter D2 represented by chemical formula 2. A second positive electrode active material,
The average particle diameter D1 is 8 μm or less,
This is a positive electrode active material for a non-aqueous electrolyte battery having a particle size ratio D2 / D1 between the average particle size D1 and the average particle size D2 of 1.5 or more.
(Chemical formula 1)
Li _a Mn _b Fe _c M _d PO ₄
(Where, 0 ≦ a ≦ 2, b + c + d ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 1, manganese (Mg), nickel (Ni), cobalt (Co), aluminum (At least one selected from (Al), tungsten (W), niobium (Nb), titanium (Ti), silicon (Si), chromium (Cr), copper (Cu), zinc (Zn)).
(Chemical formula 2)
Li _v M _w M ′ _x M ″ _y O _z
(Where 0 <v <2, w + x + y ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 <z <3, and M, M ′ and M ″ are Ni (Nickel), Co (cobalt), Fe (iron), Mn (manganese), Cu (copper), Zn (zinc), Al (aluminum), Cr (chromium), V (vanadium), Ti (titanium), Mg (At least one selected from (magnesium) and Zr (zirconium).)

  The first positive electrode active material described above is preferably composed of secondary particles formed by aggregating a plurality of primary particles whose average composition is represented by chemical formula 1, and an electron conductive material is preferably interposed between the primary particles. Moreover, it is preferable that the average particle diameter of a primary particle is as small as 10 micrometers or more and 600 micrometers or less. Furthermore, the mixing amount of the first positive electrode active material is preferably 15% by weight or more and 70% by weight or less, and the mixing amount of the second positive electrode active material is preferably 30% by weight or more and 85% by weight or less.

According to a second aspect of the present invention, there is provided a first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and a second positive electrode active material having an average particle diameter D2 represented by chemical formula 2. Including
The average particle diameter D1 is 8 μm or less,
A positive electrode including a positive electrode active material having a particle size ratio D2 / D1 between the average particle size D1 and the average particle size D2 of 1.5 or more;
A negative electrode,
A non-aqueous electrolyte battery comprising a non-aqueous electrolyte.

According to a third aspect of the present invention, there is provided a first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and a second positive electrode active material having an average particle diameter D2 represented by chemical formula 2. Including
The average particle diameter D1 is 8 μm or less,
A positive electrode including a positive electrode active material having a particle size ratio D2 / D1 between the average particle size D1 and the average particle size D2 of 1.5 or more;
A negative electrode,
A high-power electronic device using a non-aqueous electrolyte battery including a non-aqueous electrolyte.

According to a fourth aspect of the present invention, there is provided a first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and a second positive electrode active material having an average composition D2 represented by chemical formula 2. Including
The average particle diameter D1 is 8 μm or less,
A positive electrode including a positive electrode active material having a particle size ratio D2 / D1 between the average particle size D1 and the average particle size D2 of 1.5 or more;
A negative electrode,
An automobile using a non-aqueous electrolyte battery including a non-aqueous electrolyte.

  In the present invention, the first positive electrode active material having high stability and the second positive electrode active material having large discharge capacity are mixed, and the average particle diameter of the first positive electrode active material slightly inferior in electronic conductivity is reduced. Thus, the volume density of the positive electrode active material can be improved by suppressing the decrease in the electronic conductivity in the first positive electrode active material and adjusting the particle size ratio D2 / D1.

  According to the present invention, it is possible to improve the energy density, obtain a high discharge capacity, increase the stability of the positive electrode active material, and obtain excellent cycle characteristics.

It is a schematic sectional drawing of the 1st example of the nonaqueous electrolyte secondary battery using the positive electrode active material by one Embodiment of this invention. It is the schematic of the 2nd example of the nonaqueous electrolyte secondary battery using the positive electrode active material by one Embodiment of this invention. FIG. 3 is an enlarged cross section of a part of the battery element shown in FIG. 2. 3 is a graph showing the measurement results of discharge capacity in Example 1. 3 is a graph showing a measurement result of a capacity retention rate in Example 1.

Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, it is not limited to the embodiment. The description will be given in the following order.
1. First Embodiment (First Example of Nonaqueous Electrolyte Battery)
2. Second embodiment (second example of nonaqueous electrolyte battery)

1. First Embodiment (First Example of Nonaqueous Electrolyte Battery)

[Configuration of non-aqueous electrolyte battery]
FIG. 1 shows a cross-sectional structure of a nonaqueous electrolyte battery using a positive electrode active material manufactured by a method according to an embodiment of the present invention.

  This non-aqueous electrolyte battery is a so-called coin-type battery. A disc-shaped positive electrode 2 accommodated in a positive electrode can 5 and a disc-shaped negative electrode 3 accommodated in a negative electrode can 6 are separated by a separator 4. Are stacked. The separator 4 is impregnated with a non-aqueous electrolyte that is a liquid electrolyte, and the peripheral portions of the positive electrode can 5 and the negative electrode can 6 are sealed by caulking through a gasket 7. The gasket 7 is for preventing leakage of the non-aqueous electrolyte filled in the positive electrode can 5 and the negative electrode can 6, and is incorporated in and integrated with the negative electrode can 5. When a solid electrolyte or gel electrolyte is used together with the nonaqueous electrolyte or instead of the nonaqueous electrolyte, a solid electrolyte layer or a gel electrolyte layer is formed on the positive electrode 2 and the negative electrode 3.

[Exterior can]
The positive electrode can 5 and the negative electrode can 6 are made of, for example, a metal such as stainless steel or aluminum (Al). The positive electrode can 5 accommodates the positive electrode 2, and also functions as a positive electrode side external terminal of the nonaqueous electrolyte battery 1. The negative electrode can 6 accommodates the negative electrode 3, and also serves as a negative electrode-side external terminal of the nonaqueous electrolyte battery 1.

[Positive electrode]
The positive electrode 2 includes, for example, a positive electrode current collector 2A and a positive electrode active material layer 2B provided on the positive electrode current collector 2A. The positive electrode current collector 2A is made of, for example, a metal foil such as an aluminum (Al) foil. The positive electrode active material layer 2B contains a positive electrode active material, and may contain a conductive agent such as carbon black or graphite and a binder such as polyvinylidene fluoride (PVdF) as necessary.

  As the positive electrode active material, a first positive electrode active material having an olivine type crystal structure represented by the following (Chemical Formula 1) and a second positive electrode active material having a layered structure or a spinel structure represented by the following (Chemical Formula 2) Are mixed and used.

(Chemical formula 1)
Li _a Mn _b Fe _c M _d PO ₄
(Where, 0 ≦ a ≦ 2, b + c + d ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 1, manganese (Mg), nickel (Ni), cobalt (Co), aluminum (At least one selected from (Al), tungsten (W), niobium (Nb), titanium (Ti), silicon (Si), chromium (Cr), copper (Cu), zinc (Zn)).

(Chemical formula 2)
Li _v M _w M ′ _x M ″ _y O _z
(Where 0 <v <2, w + x + y ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 <z <3, and M, M ′ and M ″ are Ni (Nickel), Co (cobalt), Fe (iron), Mn (manganese), Cu (copper), Zn (zinc), Al (aluminum), Cr (chromium), V (vanadium), Ti (titanium), Mg (At least one selected from (magnesium) and Zr (zirconium).)

  In addition, the 1st positive electrode active material which has an olivine type crystal structure shown by (Chemical Formula 1) makes primary particles of the olivine compound into secondary particles. Moreover, it is preferable that the primary particles before the secondary particles are coated with an electron conductive material such as a carbon material for the purpose of improving the electron conductivity on the particle surface. The configuration of the first positive electrode active material will be described later.

  Moreover, in this invention, the average particle diameter D1 of the 1st positive electrode active material which has the olivine type crystal structure shown by (Chemical Formula 1), and the 2nd positive electrode which has the layered structure or spinel structure shown by (Chemical Formula 2). The particle size ratio D2 / D1 with respect to the average particle size D2 of the active material is 1.5 or more.

[Characteristics of first positive electrode active material and second positive electrode active material]
Is represented by the general formula _{Li v M w M 'x M} ''y O z, a second cathode active material having a layered or spinel structure has a characteristic that the discharge capacity per weight of active material is large . On the other hand, when used as a positive electrode active material of a secondary battery, the stability in a charged state is lowered. This is because the stability of the octahedral crystal structure around the transition metal produced during charging is low and the reactivity with the electrolyte is high.

In contrast, the first positive electrode active material represented by the general formula Li _a Mn _b Fe _c M _d PO ₄ and having an olivine type crystal structure is charged when used as the positive electrode active material of the secondary battery. Since the crystal structure change due to the discharge is small, the cycle characteristics are excellent. In addition, since oxygen atoms in the crystal are stably present due to covalent bond with phosphorus (P), there is an advantage that the possibility of oxygen release is small and the safety is excellent even when the battery is exposed to a high temperature environment. is there. Furthermore, since the olivine compound is a material based on iron (Fe) or manganese (Mn), which are more resource-rich and cheaper than cobalt (Co), an inexpensive non-aqueous electrolyte battery can be realized.

  On the other hand, when the first positive electrode active material is used alone as the positive electrode active material, the energy density per volume is low and the increase in capacity cannot be satisfied. The discharge capacity per weight of the olivine compound is at most equivalent to that of lithium cobaltate even if it has a high charge / discharge capacity. Furthermore, the true density of the olivine compound is about 30% lower than that of lithium cobaltate and lithium nickelate. In addition, the olivine compound has a problem of high resistance and low electron conductivity.

  Therefore, a nonaqueous electrolyte battery excellent in cycle characteristics and energy density can be configured by mixing the first positive electrode active material and the second positive electrode active material as the positive electrode active material. Since the above-mentioned oxide has high electronic conductivity, the low conductivity of the olivine compound itself is compensated by mixing the oxide and the olivine compound.

  At this time, in order to improve the electronic conductivity of the first positive electrode active material, the average particle size is reduced. Specifically, primary particles of the olivine compound are converted into secondary particles to form a first positive electrode active material, and the average particle diameter D1 of the first positive electrode active material (secondary particles of the olivine compound) is the second positive electrode active material. It becomes smaller than the substance (D2 / D1 ≧ 1.5). As a result, the olivine compound is mixed in the gap between the oxides, the volume density of the positive electrode active material is improved, and the discharge capacity per volume is improved.

  Here, in order to improve the volume density of two types of positive electrode active materials, the average particle diameter of one positive electrode active material should just be small with respect to the other average particle diameter. However, in the present invention, in view of the characteristics of the olivine compound and the oxide as positive electrode active materials, the olivine compound is controlled to be smaller than the particle size of the oxide.

  The average particle size of the primary particles of the olivine compound is preferably, for example, from 10 nm to 600 nm. Moreover, it is preferable that the average particle diameter of the 1st positive electrode active material which is a secondary particle of an olivine compound is 8 micrometers or less, for example. The average particle diameter of the first positive electrode active material can be adjusted by conditions for granulating secondary particles, classification of secondary particles after granulation, and the like.

  The reason why the olivine compound is used as secondary particles is to obtain electronic conductivity and reduce the amount of binder used. When the particles are made smaller, the specific surface area becomes larger. For example, when particles having an average particle diameter of 10 nm or more and 600 nm or less are used as the positive electrode active material, a large amount of binder is required. For this reason, energy density can be remarkably improved without increasing the usage-amount of a binder by using as a 1st positive electrode active material the secondary particle which interposed the electroconductive substance between primary particles. .

  On the other hand, since the oxide has high electron conductivity, sufficient battery characteristics can be obtained even when the average particle diameter D2 is slightly large. The average particle size of the oxide is preferably about 20 μm or less in a region where the particle size ratio D2 / D1 satisfies the condition of 1.5 or more.

  Moreover, in order to improve the electronic conductivity of the surface of the first positive electrode active material, it is preferable to coat and deposit a carbon material on the primary particle surface of the olivine compound. By making the first positive electrode active material a secondary particle in which a plurality of primary particles are aggregated and an electron conductive material is interposed between the primary particles, the electron conductivity can be improved.

  The secondary particles of the olivine compound can be granulated by, for example, a spray drying method. In addition, when the surface of the primary particles is coated / attached with the carbonaceous material, the secondary particles are granulated by dispersing the carbonaceous material and the primary particles together in the dispersion medium when the secondary particles are granulated. Thus, secondary particles in which a plurality of primary particles coated with a carbonaceous material are collected can be obtained.

  Here, in the present invention, the above-mentioned “average particle diameter D1” and “average particle diameter D2” indicate the median diameters (D50) of the first positive electrode active material and the second positive electrode active material, respectively. Note that it is preferable that 95% by volume or more of the first positive electrode active material is present in a range of 0.3 to 2.5 times the average particle diameter D1. Further, it is preferable that 95% by volume or more of the second positive electrode active material is present in a range of 0.3 to 2.5 times the average particle diameter D2.

In the present invention, the mixing amount of the first positive electrode active material Li _a Mn _b Fe _c M _d PO ₄ is in the range of 15 wt% to 70 wt%, and the second positive electrode active material Li _v M _w M ′ _x The mixing amount of M ″ _y O _z is preferably 30% by weight or more and 85% by weight or less. That is, the weight mixing ratio of the first positive electrode active material and the second positive electrode active material is preferably in the range of 15:85 to 70:30. When the mixing amount of the first positive electrode active material is too small, the stability of the whole positive electrode active material is lowered, and the cycle characteristics are lowered. On the other hand, when the mixing amount of the second positive electrode active material is too small, the discharge capacity is lowered.

  As the binder, for example, polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE) can be used. As the conductive agent, carbon materials such as fibrous carbon and carbon black can be used.

[Negative electrode]
The negative electrode 3 includes, for example, a negative electrode current collector 3A and a negative electrode active material layer 4B provided on the negative electrode current collector 3A. The negative electrode current collector 3A is made of, for example, a metal foil such as a copper (Cu) foil.

  The negative electrode active material layer 4B is selected from, for example, a negative electrode material capable of inserting and extracting lithium, metal lithium, a metal or semiconductor capable of forming an alloy or compound with lithium, or an alloy or compound thereof as the negative electrode active material. Any one or two or more types are contained, and are configured with a binder such as polyvinylidene fluoride as necessary.

  Examples of the negative electrode material capable of inserting and extracting lithium include carbonaceous materials, metal compounds, tin, tin alloys, silicon, silicon alloys, and conductive polymers, and any one or more of these are mixed. Used. When the positive electrode active material according to one embodiment of the present invention is used, a carbonaceous material is preferably used as the negative electrode material.

  Examples of the carbonaceous material include non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbon, pitch coke, needle coke, petroleum coke, and other cokes, graphite, glassy carbon, phenolic resin, and furan resin. And the like, and carbonized organic polymer compound fired bodies, carbon fibers, activated carbon, carbon blacks and the like. If the carbonaceous material has insufficient electronic conductivity for the purpose of current collection, it is also preferable to add a conductive agent.

  Examples of the metal lithium, lithium alloy or compound include, for example, the chemical formula DsEtLiu (wherein D is at least one of a metal element and a semiconductor element capable of forming an alloy or compound with lithium, and E is a metal element other than lithium and D) And at least one kind of semiconductor element, and values of s, t, and u are s> 0, t ≧ 0, and u ≧ 0, respectively.

  Among the materials represented by the chemical formula DsEtLiu, the metal element or semiconductor element capable of forming an alloy or compound with lithium is particularly preferably a group 4B metal element or semiconductor element, particularly preferably silicon (Si) or tin (Sn). And most preferably silicon (Si). Oxides such as iron oxide, ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, tin oxide, etc. that dope and dedoped lithium with a relatively low potential, and other nitrides can also be used.

The negative electrode active material may be a titanium-containing oxide such as a titanium-containing metal composite oxide or a titanium-based oxide. Examples of titanium-containing metal composite oxides include titanium-based oxides that do not contain lithium during lithium oxide synthesis, lithium-titanium oxides, and lithium-titanium composite oxides in which some of the constituent elements of lithium-titanium oxide are replaced with different elements. And so on. Examples of the lithium titanium oxide include lithium titanate having a spinel structure (for example, Li _{4 + x} Ti ₅ O ₁₂ (x is 0 ≦ x ≦ 3)), ramsteride type lithium titanate (for example, Li _{2 + y} Ti ₃ O ₇ (where y is 0 ≦ y ≦ 3), etc. These lithium titanates occlude lithium ions at a potential of about 1.5 V with respect to the electrode potential of lithium, and aluminum foil or aluminum This is preferable because it is an electrochemically very stable material with respect to the current collector of the alloy foil.

[Separator]
The separator 4 separates the positive electrode 2 and the negative electrode 3 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. As the material of the separator 4, those that have been used in conventional batteries can be used. Among them, a polyolefin fine material that has an excellent short-circuit prevention effect and can improve battery safety due to a shutdown effect. It is particularly preferred to use a porous film. For example, a microporous film made of polyethylene or polypropylene resin is preferable.

  Further, as the material of the separator 4, a material obtained by laminating or mixing polyethylene having a lower shutdown temperature and polypropylene having excellent oxidation resistance can be used. A separator made of such a material is more preferable in terms of achieving both shutdown performance and float characteristics. In the case where a solid electrolyte or a gel electrolyte is used as the electrolyte, the separator 4 is not necessarily required.

[Non-aqueous electrolyte]
The nonaqueous electrolytic solution is obtained by dissolving an electrolyte salt in a nonaqueous solvent, and exhibits ion conductivity when the electrolyte salt is ionized. The electrolytic solution is impregnated in the separator 4. The separator 4 is not particularly limited, and a conventional non-aqueous solvent electrolyte or the like is used.

Examples of the electrolyte salt include lithium hexafluorophosphate (LiPF ₆ ), bis (pentafluoroethanesulfonyl) imide lithium (Li (C ₂ F ₅ SO ₂ ) ₂ N), lithium perchlorate (LiClO ₄ ), Lithium hexafluoroarsenate (LiAsF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium trifluoromethanesulfonate (LiSO ₃ CF ₃ ), lithium bis (trifluoromethanesulfonyl) imide (Li (CF ₃ SO ₂ ) ₂ N), tris (trifluoromethanesulfonyl) methyllithium (LiC (SO ₂ CF ₃ ) ₃ ), lithium chloride (LiCl), lithium bromide (LiBr), LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , _{LiCF 3 SO 3, LiN (SO} 2 CF 3) 2, LiAlCl 4, LiSiF 6, difluoro [oxalato O, O '] lithium borate, or the like of lithium bis (oxalato) borate. Among these, LiPF ₆ is particularly preferable because it can obtain high ionic conductivity and improve cycle characteristics. As the electrolyte salt, any one selected from the above may be used alone, or a plurality of kinds may be mixed and used.

  Examples of the non-aqueous solvent for dissolving the electrolyte salt include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-fluoro-1,3-dioxolan-2-one, γ -Butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, methyl acetate, methyl propionate, ethyl propionate, acetonitrile , Glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, nitromethane, nitroethane, sulfolane, dimethyl sulfoxide Room temperature molten salts such as trimethyl phosphate, triethyl phosphate, ethylene sulfite, bistrifluoromethylsulfonylimide, and trimethylhexylammonium. Among them, ethylene carbonate, propylene carbonate, vinylene carbonate, 4-fluoro-1,3-dioxolan-2-one, dimethyl carbonate, ethyl methyl carbonate or ethylene sulfite has excellent charge / discharge capacity characteristics and charge / discharge cycle characteristics. This is preferable. Any one of the solvents may be used alone, or a plurality of the solvents may be mixed and used.

  In this nonaqueous electrolyte battery, when discharged, for example, lithium ions are released from the negative electrode 3 or lithium metal is eluted as lithium ions, and reacts with the positive electrode active material layer 2B through the electrolytic solution. When charging is performed, for example, lithium ions are separated from the positive electrode active material layer 2B, and are inserted into the negative electrode 3 through the electrolytic solution or deposited as lithium metal.

(1-2) Manufacturing Method of Nonaqueous Electrolyte Battery Next, a manufacturing method of the nonaqueous electrolyte battery according to the first example will be described.

[Production method of positive electrode]
The positive electrode 2 is produced as described below. First, the synthesis of the first positive electrode active material of the present invention will be described.

The first positive electrode active material is an olivine compound Li _a Mn _b Fe _c M _d PO ₄ (where 0 ≦ a ≦ 2, b + c + d ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 1, and M is manganese (Mg), nickel (Ni), cobalt (Co), aluminum (Al), tungsten (W), niobium (Nb), titanium (Ti), silicon (Si) , Chromium (Cr), copper (Cu), zinc (Zn)) is a secondary particle obtained by aggregating a plurality of primary particles, and it is preferable that an electron conductive substance is interposed between the primary particles.

First, in a solvent containing water as a main component, Li source, Mn source, Fe source, M source (M is manganese (Mg), nickel (Ni), cobalt (Co), aluminum (Al), tungsten (W), Niobium (Nb), Titanium (Ti), Silicon (Si), Chromium (Cr), Copper (Cu), Zinc (Zn)), PO ₄ source, and electron conductive material or precursor of this electron conductive material The body is added, and then the solution or suspension is made into secondary particles by spray drying or the like to form dry particles.

  Next, the dried particles are heat-treated at 350 to 1150 ° C, preferably 350 to 1100 ° C. By the heat treatment, the first positive electrode active material of the present invention is formed.

  As a solvent containing water as a main component, pure water, water-alcohol solution, water-ketone solution, or water-ether solution can be used. However, pure water is preferable from the viewpoint of ease of use and safety. preferable.

  The raw material of the electrode material is not particularly limited. Examples of the Li source include lithium inorganic acid salts such as lithium chloride, lithium bromide, lithium carbonate, lithium nitrate, lithium sulfate, lithium phosphate, and lithium hydroxide, lithium acetate, Lithium organic acid compounds such as lithium organic acid salts such as lithium oxalate or lithium alkoxides such as lithium ethoxide are used.

  Examples of the Fe source include iron (II) oxalate dihydrate, iron (II) phosphate octahydrate, iron (II) chloride hydrate, iron (II) sulfate heptahydrate, iron acetate ( II) Tetrahydrate, iron (III) phosphate hydrate, etc. are used.

  As the Mn source, for example, a salt such as manganese chloride (II), manganese acetate (II), manganese phosphate (II) trihydrate and the like is used.

Examples of the PO ₄ source include phosphoric acids such as orthophosphoric acid and metaphosphoric acid, and phosphoric acids such as diammonium hydrogen phosphate ((NH ₄ ) ₂ HPO ₄ ) and ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ). An ammonium hydrogen salt is used.

  Although it does not specifically limit as M source, For example, if it is aluminum (Al), salts, such as aluminum hydroxide and aluminum alkoxide, will be mentioned.

  Examples of the electron conductive material include carbon (C), gold (Au), platinum (Pt), silver (Ag), titanium (Ti), V (vanadium), Sn (tin), Nb (niobium), and Zr. (Zirconium), Mo (molybdenum), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir) or a compound containing one or more elements selected from the group of these oxides Among these, carbon is most preferable from the viewpoints of chemical stability, safety, production cost, and the like. Other than carbon, noble metals such as gold (Au), platinum (Pt), silver (Ag), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir) are preferable, and among these, silver (Ag) ) Is more preferable.

  As carbon, simple carbon is used. As the carbon simple substance, for example, carbon black, acetylene black, graphite and the like can be used, and carbon black and acetylene black are particularly preferable.

  As the precursor of the electron conductive substance, a substance that becomes an electron conductive substance upon heating is used, and among these substances, organic compounds, metal salts, metal alkoxides, metal complexes, and the like are preferably used. The organic compound is not particularly limited as long as it does not volatilize when heated. For example, polyethylene glycol, polypropylene glycol, polyethyleneimine, polyvinyl alcohol, ethyl polyacrylate, methyl polyacrylate, polyvinyl butyral, polyvinyl Polymer compounds such as pyrrolidone, sugars such as sugar alcohol, sugar ester, cellulose, water-soluble organic surfactants such as polyglycerol, polyglycerol ester, sorbitan ester, polyoxyethylene sorbitan, phosphate ester, phosphate ester salt, etc. Are preferably used.

  In addition, in order to use carbon as an electron conductive substance, when an organic compound is blended as a precursor of an electron conductive substance in the above-described solution or suspension, an organic compound soluble in a solvent is used. It is preferable. As a result, not only other components but also carbon is uniformly dispersed and mixed in the solution at the molecular level, and when the secondary particles are produced, carbon can be present more uniformly in the secondary particles.

  In the spray-drying (spray-drying) method, primary particles coated with an electron-conducting substance are instantaneously dispersed by dispersing in a solvent together with the carbonaceous material covering the primary particles and spraying in a high-temperature atmosphere. Aggregated secondary particles can be formed. The average particle diameter of the first positive electrode active material can be changed by adjusting the concentration of the solvent in which the primary particles are dispersed, adjusting other granulation conditions, and classifying the secondary particles.

  Next, the first positive electrode active material composed of the olivine compound secondary particles as described above and the second positive electrode active material composed of the oxide are weighed so as to have a predetermined weight mixing ratio. , Mix. At this time, the particle size ratio D2 / D1 between the average particle diameter D1 of the first positive electrode active material and the average particle diameter D2 of the second positive electrode active material is adjusted to be 1.5 or more. Then, a mixed positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP). A positive electrode mixture slurry is obtained.

  Subsequently, after applying the positive electrode mixture slurry to the positive electrode current collector 2A and removing the solvent, the positive electrode active material layer 2B is formed by compression molding with a roll press or the like, and the positive electrode 2 is produced by punching into a pellet shape. To do.

[Production method of negative electrode]
The negative electrode 3 is produced as described below. First, for example, a negative electrode active material and a binder are mixed to prepare a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a negative electrode mixture slurry. Next, after applying this negative electrode mixture slurry to the negative electrode current collector 3A and removing the solvent, the negative electrode active material layer 4B is formed by compression molding using a roll press or the like, and the negative electrode 3 is formed by punching into a pellet. Make it.

  Moreover, the negative electrode active material layer 4B may be formed by, for example, a vapor phase method, a liquid phase method, or a firing method, or a combination of two or more thereof. As the vapor phase method, for example, a physical deposition method or a chemical deposition method can be used. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal CVD (Chemical Vapor Deposition), or the like. A chemical vapor deposition method) or a plasma CVD method can be used. As the liquid phase method, a known method such as electrolytic plating or electroless plating can be used. A known method can also be used for the firing method, and for example, an atmosphere firing method, a reaction firing method, or a hot press firing method can be used.

[Assembly of non-aqueous electrolyte battery]
Subsequently, the negative electrode 3 and the separator 4 are accommodated in this order in the central portion of the negative electrode can 6, and an electrolytic solution is injected from above the separator 4. Subsequently, the positive electrode can 5 containing the positive electrode 2 is placed on the negative electrode can 6 and caulked through the gasket 7 to fix the positive electrode can 5 and the negative electrode can 6. Thus, the nonaqueous electrolyte battery 1 as shown in FIG. 1 is formed.

  The nonaqueous electrolyte battery produced in the first embodiment is composed of a first positive electrode active material made of olivine compound formed into secondary particles and an oxide, and has an average particle diameter larger than that of the first positive electrode active material. A second positive electrode active material having a large size is mixed and used for the positive electrode. Thereby, both high energy density and cycle characteristics can be achieved. In addition, the nonaqueous electrolyte battery of the present invention having such performances can be used for portable devices that consume a large amount of power due to high functionality, automobiles, electric bicycles, motorcycles that require a large current for driving. It can be suitably used for power supply applications such as high-power electronic devices such as electric tools.

2. Second embodiment (second example of nonaqueous electrolyte battery)
In the second embodiment, a nonaqueous electrolyte battery covered with a laminate film will be described.

[Configuration of non-aqueous electrolyte battery]
FIG. 2 shows the structure of a nonaqueous electrolyte battery using a positive electrode active material according to an embodiment of the present invention. As shown in FIG. 2, the nonaqueous electrolyte battery is sealed by housing the battery element 10 in an exterior material 19 made of a moisture-proof laminate film and welding the periphery of the battery element 10. The battery element 10 is provided with a positive electrode terminal 15 and a negative electrode terminal 16, and these leads are sandwiched between outer packaging materials 19 and pulled out to the outside. An adhesive film 17 is coated on both surfaces of the positive electrode terminal 15 and the negative electrode terminal 16 in order to improve the adhesion to the exterior material 19.

  The exterior material 19 has, for example, a laminated structure in which an adhesive layer, a metal layer, and a surface protective layer are sequentially laminated. The adhesive layer is made of a polymer film. Examples of the material constituting the polymer film include polypropylene (PP), polyethylene (PE), unstretched polypropylene (CPP), linear low density polyethylene (LLDPE), and low density. A polyethylene (LDPE) is mentioned. The metal layer is made of a metal foil, and an example of a material constituting the metal foil is aluminum (Al). Moreover, as a material which comprises metal foil, it is also possible to use metals other than aluminum (Al), for example. Examples of the material constituting the surface protective layer include nylon (Ny) and polyethylene terephthalate (PET). The surface on the adhesive layer side is a storage surface on the side where the battery element 10 is stored.

  For example, as shown in FIG. 3, the battery element 10 includes a strip-shaped negative electrode 12 having a gel electrolyte layer 13 provided on both sides, a separator 14, and a strip-shaped positive electrode 11 having a gel electrolyte layer 13 provided on both sides, This is a wound battery element 10 that is laminated with a separator 14 and wound in the longitudinal direction.

  The positive electrode 11 includes a strip-shaped positive electrode current collector 11A and a positive electrode active material layer 11B formed on both surfaces of the positive electrode current collector 11A. The positive electrode active material layer 11B can be formed in the same manner as in the first embodiment.

  One end of the positive electrode 11 in the longitudinal direction is provided with a positive electrode terminal 15 connected by, for example, spot welding or ultrasonic welding. As a material of the positive electrode terminal 15, for example, a metal such as aluminum can be used.

  The negative electrode 12 includes a strip-shaped negative electrode current collector 12A and a negative electrode active material layer 12B formed on both surfaces of the negative electrode current collector 12A. The negative electrode active material layer 12B can be formed in the same manner as in the first embodiment.

  Further, similarly to the positive electrode 11, a negative electrode terminal 16 connected by, for example, spot welding or ultrasonic welding is also provided at one end portion of the negative electrode 12 in the longitudinal direction. As the material of the negative electrode terminal 16, for example, copper (Cu), nickel (Ni), or the like can be used.

  The positive electrode current collector 11A, the positive electrode active material layer 11B, the negative electrode current collector 12A, and the negative electrode active material layer 12B are the same as in the first example.

  The gel electrolyte layer 13 includes an electrolytic solution and a polymer compound serving as a holding body that holds the electrolytic solution, and has a so-called gel shape. The gel electrolyte layer 13 is preferable because it can obtain high ionic conductivity and prevent battery leakage. The configuration of the electrolytic solution (that is, the liquid solvent and the electrolyte salt) is the same as that in the first example.

  Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, and polysiloxane. , Polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene or polycarbonate. In particular, from the viewpoint of electrochemical stability, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene, or polyethylene oxide is preferable.

[Method for producing non-aqueous electrolyte battery]
Next, a method for manufacturing the nonaqueous electrolyte battery according to the second example will be described. First, a precursor solution containing a solvent, an electrolyte salt, a polymer compound, and a mixed solvent is applied to each of the positive electrode 11 and the negative electrode 12, and the mixed solvent is volatilized to form the gel electrolyte layer 13. In addition, the positive electrode terminal 15 is attached to the end of the positive electrode current collector 11A in advance by welding, and the negative electrode terminal 16 is attached to the end of the negative electrode current collector 12A by welding.

  Next, the positive electrode 11 and the negative electrode 12 on which the gel electrolyte layer 13 is formed are laminated through a separator 14 to form a laminated body, and then the laminated body is wound in the longitudinal direction to form a wound battery element. 10 is formed.

  Next, a recess 18 is formed by deep-drawing the exterior material 19 made of a laminate film, the battery element 10 is inserted into the recess 18, and an unprocessed portion of the exterior material 19 is folded back to the upper portion of the recess 18. The outer peripheral part of is thermally welded and sealed. As described above, the nonaqueous electrolyte battery according to the second example is manufactured.

  Hereinafter, the present invention will be described in more detail based on specific experimental results. Below, the positive electrode active material to which this invention was applied was produced, the battery was produced using the obtained positive electrode active material, and the characteristic was evaluated. In addition, this invention is not limited to the following examples, In the range which does not deviate from the summary of this invention, it can change suitably.

In the following examples, Li _a Mn _b Fe _c M _d PO ₄ olivine compound formed into secondary particles and Li _v M _w M ′ _x M ″ _y O _z oxide composed of primary particles are mixed. The characteristics of the secondary battery used as the positive electrode active material were evaluated.

[Example 1]
<Sample 1-1> to <Sample 1-6>
[Production of positive electrode]
As the positive electrode active material, a material in which an olivine compound LiFePO ₄ having an average particle diameter D1 of 0.58 μm and a layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ having an average particle diameter D2 of 13.2 μm was used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 22.8.

  In addition, the olivine compound used was a secondary particle in which a plurality of primary particles (primary particle diameter: 150 nm) were aggregated and an electron conductive substance was interposed between the primary particles. The above-mentioned average particle diameter D1 of the olivine compound is the average particle diameter of the secondary particles. The layered oxide is a primary particle.

The weight mixing ratio of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ (olivine compound: layered oxide) is 70:30 for the sample 1-1, 60:40 for the sample 1-2, Sample 1-3 was 40:60, Sample 1-4 was 20:80, Sample 1-5 was 75:25, and Sample 1-6 was 10:90.

  90.8 parts by mass of the positive electrode active material as described above, 4.2 parts by mass of graphite as a conductive agent, and 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder are mixed to prepare a positive electrode mixture. did. This positive electrode mixture was dispersed in N-methyl-2-pyrrolidone as a solvent to obtain a paste-like positive electrode mixture slurry. Next, the positive electrode mixture slurry was uniformly applied to one surface of a positive electrode current collector made of a strip-shaped aluminum foil having a thickness of 15 μm, dried, and compression-molded with a roll press to form a positive electrode active material layer. Finally, the positive electrode current collector on which the positive electrode active material layer was formed was punched into a disc shape having a predetermined size to form a pellet-shaped positive electrode.

[Production of negative electrode]
A negative electrode mixture was prepared by mixing 95 parts by mass of pulverized graphite powder as a negative electrode active material and 5 parts by mass of polyvinylidene fluoride as a binder. This negative electrode mixture was dispersed in N-methyl-2-pyrrolidone as a solvent to obtain a paste-like negative electrode mixture slurry. Next, the negative electrode mixture slurry was uniformly applied to one surface of a negative electrode current collector made of a copper foil having a thickness of 15 μm, dried, and compression molded with a roll press to form a negative electrode active material layer. Finally, the negative electrode current collector on which the negative electrode active material layer was formed was punched into a disk shape having a predetermined size to form a pellet-shaped negative electrode.

[Preparation of electrolyte]
As an electrolytic solution, a mixed solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed at a volume ratio of 2: 2: 6, and lithium hexafluorophosphate as an electrolyte salt ( The one containing LiPF ₆ ) was used. The concentration of lithium hexafluorophosphate (LiPF ₆ ) in the electrolyte was 1 mol / dm ³ .

[Separator]
As the separator, a polyethylene porous film having a thickness of 23 μm was used.

[Production of test battery]
The produced pellet-like positive electrode and negative electrode were laminated with a positive electrode active material layer and a negative electrode active material layer facing each other through a separator, and were accommodated in the exterior cup and the exterior can and caulked via a gasket. As a result, a test battery composed of a coin-type nonaqueous electrolyte battery having a diameter of 20 mm and a height of 1.6 mm was produced.

<Sample 1-7> to <Sample 1-12>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 2.0 μm was used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 6.6.

  In addition, the olivine compound is composed of a plurality of primary particles (primary particle diameter: 150 nm), and secondary particles in which an electron conductive substance is interposed between the primary particles are used. The average particle diameter D1 of the olivine compound is as follows: Average particle size of secondary particles. The secondary particles of the olivine compound were granulated by a spray drying method. The average particle diameter D1 of the olivine compound is obtained by dispersing the primary particles of the olivine compound in the dispersion medium, adjusting the conditions for granulating the secondary particles by spray drying, and classifying the secondary particles after granulation. It changed by. The layered oxide is a primary particle.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ is 70:30 for the sample 1-7 and 60:60 for the sample 1-8. 40, Sample 1-9 is 40:60, Sample 1-10 is 20:80, Sample 1-11 is 75:25, and Sample 1-12 is 10:90. Similarly, a test secondary battery was produced.

<Sample 1-13> to <Sample 1-18>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 5.9 μm was used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution analyzer was 2.2.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ is 70:30 for the sample 1-13 and 60:60 for the sample 1-14. 40, Sample 1-15 is 40:60, Sample 1-16 is 20:80, Sample 1-17 is 75:25, and Sample 1-18 is 10:90. Similarly, a test secondary battery was produced.

<Sample 1-19> to <Sample 1-24>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 13 μm was used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 1.0.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ is 70:30 for the sample 1-19 and 60:60 for the sample 1-20. 40, Sample 1-21 is 40:60, Sample 1-22 is 20:80, Sample 1-23 is 75:25, Sample 1-24 is 10:90, and Sample 1-1 Similarly, a test secondary battery was produced.

[Test battery evaluation]
(A) Discharge capacity When the battery for testing of each Example and Comparative Example was charged at a constant current in a constant temperature bath at 25 ° C. under a current density of 15 mA / g and the battery voltage reached 4.2V. Switched to constant voltage charging. Then, constant current discharge was performed until the battery voltage became 2.0 V under a current density of 150 mA / g, and the battery capacity at the time of discharge was measured.

In addition, discharge capacity was made into the discharge capacity per positive electrode volume, and calculated | required by following Formula.
Discharge capacity per volume [mAh / cc] = discharge capacity [mAh / g] at a current value of 150 mA / g × positive electrode volume density [g / cc]

  The current value at the time of measuring the discharge capacity was set to 150 mA / g because there was no great difference in the discharge capacity per active material at a current value of 150 mA / g in the range of the particle diameter of the positive electrode active material used in Example 1. This is because it becomes easier to evaluate the difference in battery performance depending on the volume density of the positive electrode.

(B) Charging / discharging cycle characteristics The test batteries of each Example and Comparative Example were charged at a constant current in a constant temperature bath of 60 ° C under a current density of 15 mA / g, and the battery voltage was 4.2V. It switched to constant voltage charge at the time. Then, constant current discharge was performed until the battery voltage became 2.0 V under the condition of a current density of 150 mA / g, and the battery capacity at the time of the first discharge (initial discharge capacity) was measured.

Charging / discharging under the above-mentioned conditions was repeated 100 cycles, and the capacity retention rate at the 100th cycle was determined by the following equation.
Capacity maintenance ratio [%] = (discharge capacity at 100th cycle / initial discharge capacity) × 100

  Table 1 below shows the results of Example 1.

  4 is a graph of the evaluation results of the discharge capacity of Example 1, and FIG. 5 is a graph of the evaluation results of the charge / discharge cycle characteristics of Example 1. Note that the graphs of FIGS. 4 and 5 show the particle size when the mixing ratio of the olivine compound and the layered oxide is the same (for example, Sample 1-1, 1-7, 1-13, Sample 1-19). It was set as the graph which shows how discharge capacity and a capacity | capacitance maintenance factor change with ratio.

  In FIG. 4, reference numeral 21 indicates a measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 70:30. Reference numeral 22 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 60:40. Reference numeral 23 indicates a measurement result of a discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 40:60. Reference numeral 24 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 20:80. Reference numeral 25 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 75:25. Reference numeral 26 indicates a measurement result of a discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 10:90.

  In FIG. 5, reference numeral 31 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 70:30. Reference numeral 32 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 60:40. Reference numeral 33 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 40:60. Reference numeral 34 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 20:80. Reference numeral 35 indicates the measurement result of the discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 75:25. Reference numeral 36 indicates a measurement result of a discharge capacity of a sample having a weight mixing ratio (olivine compound: layered oxide) of 10:90.

  As can be seen from the graphs of Table 1 and FIGS. 4 and 5, the discharge capacity per volume is remarkably improved for each mixture ratio having a large mixed particle size ratio. When the weight mixing ratio of the olivine compound and the layered oxide is the same, if the mixed particle size ratio is a predetermined value, specifically, 2.2 or more in Example 1, the particle size is larger between the larger particles. Small particles enter, the volume density is remarkably improved, and the discharge capacity per volume is remarkably improved.

  In Example 1, an olivine compound having a small particle size and high electronic conductivity is present around an oxide having a large particle size and high electron conductivity, but has a higher stability than the oxide. As a result, the discharge capacity per volume is improved, and the cycle characteristics are as excellent as 80% or more in 100 cycles.

  On the other hand, when the mixed particle size ratio is too small, that is, in a region where the particle size between the oxide and the olivine compound is not greatly different, the discharge capacity per volume decreases regardless of the mixed weight ratio, and which mixed weight ratio region Also, the capacity retention rate is as low as less than 80%.

  In addition, when the particle size ratio is 2.2 or more, a particularly remarkable effect is achieved particularly in view of the compatibility between the discharge capacity and the capacity retention ratio in the region where the mixing weight ratio of the olivine compound and the oxide is 20:80 to 70:30. It can be seen that When the mixing weight ratio of the olivine compound is too large, the capacity retention rate is remarkably increased, but the discharge capacity is lowered. This is because the stability is high, but many olivine compounds are inferior to oxides in terms of energy density. Moreover, when the mixing weight ratio of the oxide is too large, the capacity retention rate is lowered although the discharge capacity is increased. This is because the property that the cycle characteristics are good disappears because the amount of the olivine compound having a unique property that the change in crystal structure accompanying charge / discharge is small is small.

[Example 2]
In Example 2, test batteries are produced and evaluated by changing the materials of the olivine compound and the oxide.
<Sample 2-1> to <Sample 2-6>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 0.6 μm and a layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 22.

  In addition, the olivine compound used was a secondary particle in which a plurality of primary particles (primary particle diameter: 150 nm) were aggregated and an electron conductive substance was interposed between the primary particles. The above-mentioned average particle diameter D1 of the olivine compound is the average particle diameter of the secondary particles. The layered oxide is a primary particle.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ was measured in 70-1, Sample 2- Sample 2 except 60:40, sample 2-3 40:60, sample 2-4 20:80, sample 2-5 75:25, sample 2-6 10:90 A test secondary battery was produced in the same manner as in 1-1.

<Sample 2-7> to <Sample 2-12>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 2.9 μm and a layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 4.6.

The weight mixing ratio of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ (olivine compound: layered oxide) was changed to 70:30 for the sample 2-7, sample 2 Sample 8 except sample 8 is set to 60:40, sample 2-9 is set to 40:60, sample 2-10 is set to 20:80, sample 2-11 is set to 75:25, and sample 2-12 is set to 10:90. A test secondary battery was produced in the same manner as in 2-1.

<Sample 2-13> to <Sample 2-18>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 6.5 μm and a layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 2.0.

The weight mixing ratio of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ (olivine compound: layered oxide) was changed to 70:30 for the sample 2-13 and the sample 2− 14: 60:40, Sample 2-15: 40:60, Sample 2-16: 20:80, Sample 2-17: 75:25, Sample 2-18: 10:90 A test secondary battery was produced in the same manner as in 2-1.

<Sample 2-19> to <Sample 2-24>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 13.5 μm and a layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 0.98.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.8 Co _0.15 Al _0.05 O ₂ was changed from 70-30 to Sample 2-19 for the sample 2-19. Except for setting 20: 60:40, Sample 2-21: 40:60, Sample 2-22: 20:80, Sample 2-23: 75:25, Sample 2-24: 10:90 A test secondary battery was produced in the same manner as in 2-1.

[Test battery evaluation]
(A) Discharge capacity About the test battery of each Example and the comparative example, the battery capacity at the time of discharge was measured like Example 1, and the discharge capacity per volume was calculated | required by following Formula.
Discharge capacity [mAh / cc] = discharge capacity [mAh / g] at a current value of 150 mA / g × positive electrode volume density [g / cc]

(B) Charging / Discharging Cycle Characteristics For the test batteries of each Example and Comparative Example, the capacity retention rate at the 100th cycle was determined by the following formula, as in Example 1.
Capacity maintenance ratio [%] = (discharge capacity at 100th cycle / initial discharge capacity) × 100

  Table 2 below shows the results of Example 2.

[Example 3]
In Example 3, a test battery is produced and evaluated by changing the materials of the olivine compound and the layered oxide.

<Sample 3-1> to <Sample 3-6>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 0.58 μm and a layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution analyzer was 28.4.

  In addition, the olivine compound used was a secondary particle in which a plurality of primary particles (primary particle diameter: 150 nm) were aggregated and an electron conductive substance was interposed between the primary particles. The above-mentioned average particle diameter D1 of the olivine compound is the average particle diameter of the secondary particles. The layered oxide is a primary particle.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 3-1 and 60:60 for the sample 3-2. 40, Sample 3-3 is 40:60, Sample 3-4 is 20:80, Sample 3-5 is 75:25, and Sample 3-6 is 10:90. Similarly, a test secondary battery was produced.

<Sample 3-7> to <Sample 3-12>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 2.0 μm and a layered oxide LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 8.3.

And the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 3-7 and 60:60 for the sample 3-8. 40, Sample 3-9 is 40:60, Sample 3-10 is 20:80, Sample 3-11 is 75:25, and Sample 3-12 is 10:90. Similarly, a test secondary battery was produced.

<Sample 3-13> to <Sample 3-18>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 5.9 μm and a layered oxide LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 2.8.

And the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 3-13 and 60:60 for the sample 3-14. 40, Sample 3-15 is 40:60, Sample 3-16 is 20:80, Sample 3-17 is 75:25, and Sample 3-18 is 10:90. Similarly, a test secondary battery was produced.

<Sample 3-19> to <Sample 3-24>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 13 μm and a layered oxide LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 1.3.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 3-19 and 60:60 for the sample 3-20. 40, Sample 3-21 is 40:60, Sample 3-22 is 20:80, Sample 3-23 is 75:25, and Sample 3-24 is 10:90. Similarly, a test secondary battery was produced.

[Test battery evaluation]
(A) Discharge capacity About the test battery of each Example and the comparative example, the battery capacity at the time of discharge was measured like Example 1, and the discharge capacity per volume was calculated | required by following Formula.
Discharge capacity [mAh / cc] = discharge capacity [mAh / g] at a current value of 150 mA / g × positive electrode volume density [g / cc]

(B) Charging / Discharging Cycle Characteristics For the test batteries of each Example and Comparative Example, the capacity retention rate at the 100th cycle was determined by the following formula, as in Example 1.
Capacity maintenance ratio [%] = (discharge capacity at 100th cycle / initial discharge capacity) × 100

  Table 3 below shows the results of Example 3.

[Example 4]
In Example 4, a test battery is produced and evaluated by changing the materials of the olivine compound and the layered oxide.

<Sample 4-1> to <Sample 4-6>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 0.6 μm and a layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 27.5.

  In addition, the olivine compound used was a secondary particle in which a plurality of primary particles (primary particle diameter: 150 nm) were aggregated and an electron conductive substance was interposed between the primary particles. The above-mentioned average particle diameter D1 of the olivine compound is the average particle diameter of the secondary particles. The layered oxide is a primary particle.

The weight mixing ratio of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ (olivine compound: layered oxide) was changed to 70:30 for the sample 4-1, and the sample 4- Sample 2 except 60:40, sample 4-3 40:60, sample 4-4 20:80, sample 4-5 75:25, sample 4-6 10:90 A test secondary battery was produced in the same manner as in 1-1.

<Sample 4-7> to <Sample 4-12>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 2.9 μm and a layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 8.3.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ was measured as follows: Sample 4-7 was 70:30, Sample 4- Sample 8 except sample 8 is 40:60, sample 4-9 is 40:60, sample 4-10 is 20:80, sample 4-11 is 75:25, sample 4-12 is 10:90 A test secondary battery was produced in the same manner as in 4-1.

<Sample 4-13> to <Sample 4-18>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 6.5 μm and a layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 2.8.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is set to 70:30, Sample 4-13 14: 60:40, Sample 4-15: 40:60, Sample 4-16: 20:80, Sample 4-17: 75:25, Sample 4-18: 10:90 A test secondary battery was produced in the same manner as in 4-1.

<Sample 4-19> to <Sample 4-24>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 13.5 μm and a layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ having an average particle diameter D2 of 16.5 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 1.3.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is set to 70:30 for the sample 4-19 and the sample 4− Except for 20: 60:40, Sample 4-21: 40:60, Sample 4-22: 20:80, Sample 4-23: 75:25, Sample 4-24: 10:90 A test secondary battery was produced in the same manner as in 4-1.

[Test battery evaluation]
(A) Discharge capacity About the test battery of each Example and the comparative example, the battery capacity at the time of discharge was measured like Example 1, and the discharge capacity per volume was calculated | required by following Formula.
Discharge capacity [mAh / cc] = discharge capacity [mAh / g] at a current value of 150 mA / g × positive electrode volume density [g / cc]

(B) Charging / Discharging Cycle Characteristics For the test batteries of each example and comparative example, the capacity retention rate at the 100th cycle was determined by the following equation in the same manner as in Example 1.
Capacity maintenance ratio [%] = (discharge capacity at 100th cycle / initial discharge capacity) × 100

  Table 4 below shows the results of Example 4.

[Example 5]
Also in Example 5, a test battery is produced and evaluated by changing the materials of the olivine compound and the layered oxide.

<Sample 5-1> to <Sample 5-6>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 0.58 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 19.

  In addition, the olivine compound used was a secondary particle in which a plurality of primary particles (primary particle diameter: 150 nm) were aggregated and an electron conductive substance was interposed between the primary particles. The above-mentioned average particle diameter D1 of the olivine compound is the average particle diameter of the secondary particles. The layered oxide is a primary particle.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ is 70:30 for the sample 5-1 and 60:60 for the sample 5-2. 40, Sample 5-3 is 40:60, Sample 5-4 is 20:80, Sample 5-5 is 75:25, and Sample 5-6 is 10:90. Similarly, a test secondary battery was produced.

<Sample 5-7> to <Sample 5-12>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 2.0 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 5.5.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ is 70:30 for the sample 5-7 and 60:60 for the sample 5-8. 40, Sample 5-9 is 40:60, Sample 5-10 is 20:80, Sample 5-11 is 75:25, and Sample 5-12 is 10:90. Similarly, a test secondary battery was produced.

<Sample 5-13> to <Sample 5-18>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 5.9 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 1.9.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ is 70:30 for the sample 5-13 and 60:60 for the sample 5-14. 40, Sample 5-15 is 40:60, Sample 5-16 is 20:80, Sample 5-17 is 75:25, and Sample 5-18 is 10:90. Similarly, a test secondary battery was produced.

<Sample 5-19> to <Sample 5-24>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 13 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 0.84.

Then, the weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ is 70:30 for the sample 5-19 and 60:60 for the sample 5-20. 40, Sample 5-21 is 40:60, Sample 5-22 is 20:80, Sample 5-23 is 75:25, and Sample 5-24 is 10:90. Similarly, a test secondary battery was produced.

[Test battery evaluation]
(A) Discharge capacity About the test battery of each Example and the comparative example, the battery capacity at the time of discharge was measured like Example 1, and the discharge capacity per volume was calculated | required by following Formula.
Discharge capacity [mAh / cc] = discharge capacity [mAh / g] at a current value of 150 mA / g × positive electrode volume density [g / cc]

(B) Charging / Discharging Cycle Characteristics For the test batteries of each example and comparative example, the capacity retention rate at the 100th cycle was determined by the following equation in the same manner as in Example 1.
Capacity maintenance ratio [%] = (discharge capacity at 100th cycle / initial discharge capacity) × 100

  Table 5 below shows the results of Example 5.

[Example 6]
Also in Example 6, a test battery is produced and evaluated by changing the materials of the olivine compound and the layered oxide.

<Sample 6-1> to <Sample 6-6>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 0.6 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 18.3.

  In addition, the olivine compound used was a secondary particle in which a plurality of primary particles (primary particle diameter: 150 nm) were aggregated and an electron conductive substance was interposed between the primary particles. The above-mentioned average particle diameter D1 of the olivine compound is the average particle diameter of the secondary particles. The layered oxide is a primary particle.

The weight mixing ratio of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (olivine compound: layered oxide) was changed to 70:30 for sample 6-1 and 6- Sample 2 except 60:40, sample 6-3 40:60, sample 6-4 20:80, sample 6-5 75:25, sample 6-6 10:90 A test secondary battery was produced in the same manner as in 1-1.

<Sample 6-7> to <Sample 6-12>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 2.9 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 3.8.

The weight mixing ratio of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (olivine compound: layered oxide) was changed to 70:30 for the sample 6-7, Sample 8 except sample 8 is set to 60:40, sample 6-9 is set to 40:60, sample 6-10 is set to 20:80, sample 6-11 is set to 75:25, and sample 6-12 is set to 10:90. A test secondary battery was produced in the same manner as in Example 6-1.

<Sample 6-13> to <Sample 6-18>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 6.5 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 1.7.

Then, the weight mixing ratio of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (olivine compound: layered oxide) is 70:30 in the sample 6-13, sample 6-6 14: 60:40, Sample 6-15: 40:60, Sample 6-16: 20:80, Sample 6-17: 75:25, Sample 6-18: 10:90 A test secondary battery was produced in the same manner as in Example 6-1.

<Sample 6-19> to <Sample 6-24>
As the positive electrode active material, an olivine compound LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D1 of 13.5 μm and a layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ having an average particle diameter D2 of 11 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 0.81.

Then, the weight mixing ratio of the olivine compound LiMn _0.75 Fe _0.25 PO ₄ and the layered oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (olivine compound: layered oxide) was measured for the sample 6-19 for 70:30, the sample 6-6 Except for 20: 60:40, Sample 6-21: 40:60, Sample 6-22: 20:80, Sample 6-23: 75:25, Sample 6-24: 10:90 A test secondary battery was produced in the same manner as in Example 6-1.

[Test battery evaluation]
(A) Discharge capacity About the test battery of each Example and the comparative example, the battery capacity at the time of discharge was measured like Example 1, and the discharge capacity per volume was calculated | required by following Formula.
Discharge capacity [mAh / cc] = discharge capacity [mAh / g] at a current value of 150 mA / g × positive electrode volume density [g / cc]

(B) Charging / Discharging Cycle Characteristics For the test batteries of each example and comparative example, the capacity retention rate at the 100th cycle was determined by the following equation in the same manner as in Example 1.
Capacity maintenance ratio [%] = (discharge capacity at 100th cycle / initial discharge capacity) × 100

  Table 6 below shows the results of Example 6.

  As shown in Tables 2 to 6, even when the materials of the olivine compound and the layered oxide were changed, the same effect as in Example 1 was obtained.

  For example, in Example 2, when the particle size ratio was 2.1 or more, a battery having both a discharge capacity and a capacity retention rate could be obtained. In addition, when the particle size ratio is 2.1 or more, the mixing weight ratio of the olivine compound and the layered oxide is particularly remarkable from the viewpoint of coexistence of the discharge capacity and the capacity retention ratio in the region of 20:80 to 70:30. It was found that a good effect can be obtained.

  Similarly, in Example 3, the particle size ratio is 2.8 or more, in Example 4, the particle size ratio is 2.5 or more, in Example 5, the particle size ratio is 1.9 or more, and in Example 6, the particle size ratio is 1.7 or more. Thus, a battery having both a discharge capacity and a capacity retention rate could be obtained. Further, whatever the material and particle size ratio, the mixing weight ratio of the olivine compound and the layered oxide is particularly in the range of 20:80 to 70:30, particularly from the viewpoint of coexistence of the discharge capacity and the capacity retention rate. It turned out that a remarkable effect is acquired.

[Example 7]
In Example 7, a test battery is prepared and evaluated using an olivine compound composed of primary particles.

<Sample 7-1> to <Sample 7-4>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 0.55 μm and a layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 24.

  The olivine compound is a primary particle, and primary particles in which an electron conductive material is provided on the particle surface are used. The average particle diameter D1 of the above-mentioned olivine compound is the average particle diameter of the primary particles. Similarly, the layered oxide is also a primary particle.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 7-1 and 60:60 for the sample 7-2. A test secondary battery was fabricated in the same manner as Sample 1-1 except that 40, Sample 7-3 was 40:60, and Sample 7-4 was 20:80.

<Sample 7-5> to <Sample 7-8>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 2.5 μm and a layered oxide LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 5.3.

  The olivine compound is a primary particle, and the average particle diameter D1 of the olivine compound is the average particle diameter of the primary particles.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 7-5 and 60:60 for the sample 7-6. 40, Sample 7-7 was 40:60, and Sample 7-8 was 20:80. A test secondary battery was fabricated in the same manner as Sample 7-1.

<Sample 7-9> to <Sample 7-12>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 6.3 μm and a layered oxide LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 2.1.

  The olivine compound is a primary particle, and the average particle diameter D1 of the olivine compound is the average particle diameter of the primary particles.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 7-9 and 60:60 for the sample 7-10. A test secondary battery was produced in the same manner as Sample 7-1 except that 40, Sample 7-11 was 40:60, and Sample 7-12 was 20:80.

<Sample 7-13> to <Sample 7-16>
As the positive electrode active material, an olivine compound LiFePO ₄ having an average particle diameter D1 of 13.5 μm and a layered oxide LiMn _0.75 Fe _0.25 PO ₄ having an average particle diameter D2 of 13.2 μm were used. At this time, the ratio (D2 / D1) of the average particle diameter D1 of the olivine compound and the average particle diameter D2 of the layered oxide measured by a laser diffraction particle size distribution meter was 1.0.

  The olivine compound is a primary particle, and the average particle diameter D1 of the olivine compound is the average particle diameter of the primary particles.

The weight mixing ratio (olivine compound: layered oxide) of the olivine compound LiFePO ₄ and the layered oxide LiCo _0.98 Al _0.01 Mg _0.01 O ₂ is 70:30 for the sample 7-1 and 60:60 for the sample 7-2. 40, Sample 7-3 was made 40:60, and Sample 7-4 was made 20:80. A test secondary battery was fabricated in the same manner as Sample 7-1.

[Test battery evaluation]
(A) Discharge capacity About the test battery of each Example and the comparative example, the battery capacity at the time of discharge was measured like Example 1, and the discharge capacity per volume was calculated | required by following Formula.
Discharge capacity [mAh / cc] = discharge capacity [mAh / g] at a current value of 150 mA / g × positive electrode volume density [g / cc]

(B) Charging / Discharging Cycle Characteristics For the test batteries of each example and comparative example, the capacity retention rate at the 100th cycle was determined by the following equation in the same manner as in Example 1.
Capacity maintenance ratio [%] = (discharge capacity at 100th cycle / initial discharge capacity) × 100

  Table 7 below shows the results of Example 7.

  In Example 7, the olivine compound and the layered oxide in Examples 1 to 7 were mixed with each other in a weight ratio (olivine compound: layered oxidation) that exhibited particularly remarkable battery characteristics at any particle size ratio D2 / D1. Thing) It is made to mix in the range of 20: 80-70: 30. However, as can be seen from Table 7, even in the case of a positive electrode active material in which an olivine compound and a layered oxide are mixed, the discharge capacity and cycle characteristics can be obtained by using an olivine compound consisting of primary particles as a part of the positive electrode active material. It has been found that the decrease in is remarkable.

  For example, the sample 1-1 and the sample 7-1 are compared. Sample 1-1 and Sample 7-1 have an average particle diameter D1 of the olivine compound that is substantially the same as 0.58 μm and 0.55 μm. Moreover, the weight mixing ratio of the olivine compound and the layered oxide is the same as 70:30.

  In Sample 7-1 using primary particles as the olivine compound, the discharge capacity was reduced compared to Sample 1-1 using secondary particles as the olivine compound, and the capacity retention rate was significantly reduced. Moreover, even when other samples having a close particle size ratio D2 / D1 were compared, the same deterioration in battery characteristics was observed. Thus, it was found that the battery characteristics higher when the secondary particles, which are aggregates of primary particles, are used as the olivine compound than the primary particles.

  As described above, in the positive electrode active material which is excellent in stability as the positive electrode active material and is mixed with the olivine compound composed of secondary particles and the oxide composed of primary particles having a large theoretical capacity per positive electrode volume, By adjusting the particle size ratio of the compound to the oxide, high battery characteristics can be obtained.

  In the non-aqueous electrolyte battery according to the present invention, the shape of the battery is not particularly limited. In addition to the coin type and the laminate film type described above, various shapes such as a cylindrical type, a square type, and a button type are available. Can be configured.

  Moreover, the manufacturing method of the negative electrode and the positive electrode is not limited to the above description, and a known method can be used. For example, a method of adding a known binder, a conductive material, etc. to a material and adding a solvent, a method of adding a known binder, etc. to a material and applying it by heating, a material alone or a conductive material, Various methods such as a method of producing a molded body electrode by mixing with a binder and performing a process such as molding can be used.

  More specifically, it is mixed with a binder, an organic solvent or the like as described above to form a slurry, and then applied to the current collector and dried, or the presence or absence of the binder. Alternatively, a method of producing an electrode having strength by pressure molding while applying heat to the active material can be used.

  As a battery assembly method, a known method such as a stacking method in which electrodes and separators are sequentially stacked as described above, or a winding method in which a winding is wound around a core via a separator between positive and negative electrodes can be used. The present invention is also effective when a square battery is manufactured by a winding method.

DESCRIPTION OF SYMBOLS 1 .... Nonaqueous electrolyte battery 2 .... Positive electrode 2A ... Positive electrode collector 2B ... Positive electrode mixture layer 3 .... Negative electrode 3A ... Negative electrode collector 3B ... Negative electrode Mixture layer 4 ... Separator
5 .... Positive electrode can 6 .... Negative electrode can 7 .... Gasket 10 .... Battery element 11 ... Positive electrode 11A ... Positive current collector 11B ... Positive mix layer 12 ... Negative electrode 12A ... Negative electrode current collector 12B ... Negative electrode mixture layer 13 ... Gel electrolyte layer 14 ... Separator 15 ... Positive electrode lead 16 ... Negative electrode lead 17 ... Resin piece 18 ... Recess 19 ... Exterior materials

Claims (8)

A first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and a second positive electrode active material having an average particle diameter D2 represented by chemical formula 2;
The average particle diameter D1 is 8 μm or less,
A positive electrode active material for a nonaqueous electrolyte battery, wherein a particle diameter ratio D2 / D1 between the average particle diameter D1 and the average particle diameter D2 is 1.5 or more.
(Chemical formula 1)
Li _a Mn _b Fe _c M _d PO ₄
(Where, 0 ≦ a ≦ 2, b + c + d ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 1, manganese (Mg), nickel (Ni), cobalt (Co), aluminum (At least one selected from (Al), tungsten (W), niobium (Nb), titanium (Ti), silicon (Si), chromium (Cr), copper (Cu), zinc (Zn)).
(Chemical formula 2)
Li _v M _w M ′ _x M ″ _y O _z
(Where 0 <v <2, w + x + y ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 <z <3, and M, M ′ and M ″ are Ni (Nickel), Co (cobalt), Fe (iron), Mn (manganese), Cu (copper), Zn (zinc), Al (aluminum), Cr (chromium), V (vanadium), Ti (titanium), Mg (At least one selected from (magnesium) and Zr (zirconium).) 2. The positive electrode active material for a nonaqueous electrolyte battery according to claim 1, wherein the first positive electrode active material is a secondary particle formed by aggregating a plurality of primary particles having an average composition represented by Chemical Formula 1. 3. The positive electrode active material for a non-aqueous electrolyte battery according to claim 2, wherein the first positive electrode active material comprises secondary particles in which an electron conductive material is interposed between primary particles. 4. The positive electrode active material for a non-aqueous electrolyte battery according to claim 3, wherein an average particle diameter of the primary particles of the first positive electrode active material is 10 μm or more and 600 μm or less. The mixing amount of the first positive electrode active material is 15 wt% or more and 70 wt% or less,
The positive electrode active material for a non-aqueous electrolyte battery according to claim 4, wherein a mixing amount of the second positive electrode active material is 30 wt% or more and 85 wt% or less. A first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and a second positive electrode active material having an average particle diameter D2 represented by chemical formula 2;
The average particle diameter D1 is 8 μm or less,
A positive electrode including a positive electrode active material in which a particle size ratio D2 / D1 between the average particle size D1 and the average particle size D2 is 1.5 or more;
A negative electrode,
A nonaqueous electrolyte battery comprising a nonaqueous electrolyte.
(Chemical formula 1)
Li _a Mn _b Fe _c M _d PO ₄
(Where, 0 ≦ a ≦ 2, b + c + d ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 1, manganese (Mg), nickel (Ni), cobalt (Co), aluminum (At least one selected from (Al), tungsten (W), niobium (Nb), titanium (Ti), silicon (Si), chromium (Cr), copper (Cu), zinc (Zn)).
(Chemical formula 2)
Li _v M _w M ′ _x M ″ _y O _z
(Where 0 <v <2, w + x + y ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 <z <3, and M, M ′ and M ″ are Ni (Nickel), Co (cobalt), Fe (iron), Mn (manganese), Cu (copper), Zn (zinc), Al (aluminum), Cr (chromium), V (vanadium), Ti (titanium), Mg (At least one selected from (magnesium) and Zr (zirconium).) A first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and a second positive electrode active material having an average particle diameter D2 represented by chemical formula 2;
The average particle diameter D1 is 8 μm or less,
A positive electrode including a positive electrode active material in which a particle size ratio D2 / D1 between the average particle size D1 and the average particle size D2 is 1.5 or more;
A negative electrode,
A high-power electronic device using a non-aqueous electrolyte battery comprising a non-aqueous electrolyte.
(Chemical formula 1)
Li _a Mn _b Fe _c M _d PO ₄
(Where, 0 ≦ a ≦ 2, b + c + d ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 1, manganese (Mg), nickel (Ni), cobalt (Co), aluminum (At least one selected from (Al), tungsten (W), niobium (Nb), titanium (Ti), silicon (Si), chromium (Cr), copper (Cu), zinc (Zn)).
(Chemical formula 2)
Li _v M _w M ′ _x M ″ _y O _z
(Where 0 <v <2, w + x + y ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 <z <3, and M, M ′ and M ″ are Ni (Nickel), Co (cobalt), Fe (iron), Mn (manganese), Cu (copper), Zn (zinc), Al (aluminum), Cr (chromium), V (vanadium), Ti (titanium), Mg (At least one selected from (magnesium) and Zr (zirconium).) A first positive electrode active material having an average particle diameter D1 represented by chemical formula 1 and a second positive electrode active material having an average particle diameter D2 represented by chemical formula 2;
The average particle diameter D1 is 8 μm or less,
A positive electrode including a positive electrode active material in which a particle size ratio D2 / D1 between the average particle size D1 and the average particle size D2 is 1.5 or more;
A negative electrode,
An automobile using a non-aqueous electrolyte battery comprising a non-aqueous electrolyte.
(Chemical formula 1)
Li _a Mn _b Fe _c M _d PO ₄
(Where, 0 ≦ a ≦ 2, b + c + d ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 1, manganese (Mg), nickel (Ni), cobalt (Co), aluminum (At least one selected from (Al), tungsten (W), niobium (Nb), titanium (Ti), silicon (Si), chromium (Cr), copper (Cu), zinc (Zn)).
(Chemical formula 2)
Li _v M _w M ′ _x M ″ _y O _z
(Where 0 <v <2, w + x + y ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 <z <3, and M, M ′ and M ″ are Ni (Nickel), Co (cobalt), Fe (iron), Mn (manganese), Cu (copper), Zn (zinc), Al (aluminum), Cr (chromium), V (vanadium), Ti (titanium), Mg (At least one selected from (magnesium) and Zr (zirconium).)

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