JP5314258B2 - Olivine-type lithium iron phosphate compound and method for producing the same, and positive electrode active material and non-aqueous electrolyte battery using olivine-type lithium iron phosphate compound - Google Patents

Description

Detailed Description of the Invention

  The present invention relates to an olivine-type positive electrode active material that is a low-cost, high-safety, and excellent battery property for high-speed charge / discharge, a method for producing the same, and a non-aqueous electrolyte having a positive electrode including the same It relates to batteries.

  Currently, lithium secondary batteries are widely used as power sources for electronic devices such as mobile phones, video cameras, and notebook computers. In addition, due to environmental conservation problems and energy problems, development of large-sized lithium secondary batteries that are inexpensive and highly safe for electric vehicles and nighttime electric power is being promoted.

Conventionally, a layered rock salt type LiCoO ₂ has been mainly used as a positive electrode active material of a lithium secondary battery. LiCoO ₂ is excellent in charge / discharge cycle characteristics, but the resource amount of cobalt as a raw material is small, and the cost is also expensive. Therefore, layered rock salt type LiNiO ₂ and spinel type LiMn ₂ O ₄ have been studied as alternative positive electrode active materials, but LiNiO ₂ has a problem in the safety of the charged state, and LiMn ₂ O ₄ is in a high temperature range. There is a problem with chemical stability. New cathode materials combining these elements have been proposed for small batteries, but new alternative materials are expected as positive electrode active materials for large batteries, which are more demanding in terms of cost and safety. It has been rare.

In recent years, LiFePO ₄ , which is an olivine-type positive electrode active material, has been actively developed as a material excellent in cost, safety, and reliability. This olivine-type LiFePO ₄ has been attracting attention because it has extremely high safety and stability and is low in cost, but has a problem of low electronic conductivity as a problem for practical use. As methods for improving this, mainly fine particle formation for increasing the reaction surface area, carbon coating for imparting conductivity, and the like are well known (for example, Non-Patent Document 1). It has been reported that battery characteristics can be improved particularly by nano-sized uniform particles in micronization (Non-patent Documents 2 and 3). In addition, regarding the addition of carbon, there are numerous reports on various carbon materials (for example, Patent Document 3 and Non-Patent Document 4).

  Further, many patents for different metal substitution have been proposed, but metals that clearly show the effect are limited to specific metals such as Mn and Mg, and the effect is not exhibited unless the substitution amount is large (for example, Patent Document 4). ~ 6). Further, as described in Non-Patent Document 8, there is a metal that shows an effect of improving conductivity by a small amount of substitution, but the capacity is low even at a low rate, and the capacity at a high rate is unknown.

  Further, as a method for producing olivine type lithium iron phosphate, a solid phase method using iron oxalate or iron acetate as a starting material (Patent Document 1, Non-Patent Document 5) has been generally used. In recent years, a solid-phase method using iron phosphate as a raw material (Patent Document 2), a sol-gel method for obtaining finer particles, a hydrothermal method (Non-Patent Documents 6 and 7), and the like have been reported. However, in any of the methods, the raw materials are expensive, facilities for preventing the oxidation of divalent iron are necessary, and it is difficult to obtain a target product having uniform and good crystallinity. As for the method of doping the substitution element, it is difficult to control the crystal form if the substitution element is added to the sol-gel method or the hydrothermal method, and a uniform phase can be obtained by mixing the substitution element by a general solid phase method. There was no problem. Therefore, in any method, it is difficult to industrially produce uniform finely substituted metal-containing particles with inexpensive raw materials and simple production equipment, and olivine type lithium iron phosphate having practical battery characteristics is reduced. There is a need for a manufacturing method that can be realized at low cost.

Japanese Patent No. 3484003 Japanese Patent No. 3319258 JP 2001-15111 A JP 2004-79276 A Special table 2003-520405 gazette JP 2006-73259 A A. Yamada; Electrochemistry 71, No. 3, 717-722 (2003) A.Singhal, G.Skandan, G.Amatucci, F.Badway, N.Ye, A.Manthiram, H.Ye, J.J.Xu, Journal of Power Sources 129, 38-44 (2004) K. Striebel, J. Shim, V. Srinivasan, and J. Newman, J. Electrochem. Soc., 152, No. 4, A554-A670 (2005) N. Ravet, Y. Choinard, J. F. Magnan, S. Besner, M. Gauthier, M. Armand, Journal of Power Sources 97-98, 503-507 (2001) A.K.Padhi, K.S.Nanjundaswamy, and J.B.Goodenough, J.Electrochem.Soc., 144, No.4, 1188-1194 (1997) S.Yang, P.Y.Zavalji, M.S.Whittingham, Electrochemistry Communication 3, 505-508 (2001) J. Yang and J. J. Xu, Electrochemical and Solid-State Letters, 7 (12) A515-A518 (2004) F. Croce, A. D’ Epifanio, J. Hassoun, A. Deptula, T. Olczac, and B. Scrosati, Electrochemical and Solid-State Letters, 5 (3) A47-A50 (2002)

  The present invention relates to a positive electrode active material that is excellent in cost, safety, reliability, high capacity, and capable of producing a non-electrolyte battery capable of high-speed charge / discharge, a method for producing the same, and a non-aqueous electrolyte using the same. An object is to provide a battery.

In order to produce a positive electrode active material having such excellent characteristics as described above, the present inventors diligently studied, and as a result, completed the present invention.
That is, the present invention provides the following.

[1] The average particle size is 500 nm or less, and the following general formula:
_{Li x Fe y Ti p M q} PO 4
(Wherein 0 <x <2, 0 <y <1.5, p / y = 0.001 to 0.2, q / p = 0 to 10, M is Co, Ni, Mn, (At least one metal selected from the group consisting of Zn, Cu, Mg, and Al)
An olivine type lithium iron phosphate compound represented by:

[2] The average particle diameter is 500 nm or less, the variation coefficient of the particle size distribution is 0.5 or less, the BET value is 10 to 50 m ² / g, and the X-ray diffraction peak corresponding to the crystal plane of 111 planes The olivine-type lithium iron phosphate compound according to [1], wherein the crystallite diameter (D ₁₁₁ ) determined from the half-value width according to Scherrer's formula is 20.0 to 80.0 nm.

[3] The olivine-type lithium iron phosphate compound according to [1], which has a carbon content of 0.1 to 10%.
[4] Production of olivine-type lithium iron phosphate compound according to [1], wherein an iron source containing substituted metal-containing iron oxide particles having an average particle diameter of 500 nm or less, a lithium source, and a phosphorus source are mixed and calcined. Method.

[5] The method according to [4], wherein the iron source includes iron oxide particles doped with a substitution metal and / or iron oxide particles wet-treated with a substitution metal.
[6] The method according to [4], wherein the substitution metal is at least one metal element selected from the group consisting of Ti, Co, Ni, Mn, Zn, Cu, Mg, and Al.

[7] The method according to [4], wherein the iron oxide particles are obtained by reacting an iron salt and an alkali.
[8] The method of [4], wherein the iron oxide particles are magnetite.

[9] The method according to [4], wherein the alkali is an alkali hydroxide and / or an alkali carbonate.
[10] The method according to [4], wherein an iron source, a lithium source, and a phosphorus source, and carbon or / and a carbon precursor containing substituted metal-containing iron oxide particles having an average particle diameter of 500 nm or less are mixed and calcined. .

[11] The method according to any one of [4] to [10], wherein the firing is performed in an inert gas atmosphere or a reducing atmosphere.
[12] The method according to [11], wherein the firing is performed in an N ₂ atmosphere.

[13] A positive electrode active material comprising the olivine type lithium iron phosphate compound of [1] to [3] or the olivine type lithium iron phosphate compound obtained by any of the methods of [4] to [12].
[14] A nonaqueous electrolyte battery having a positive electrode including the positive electrode active material according to [13].

  [15] At least one metal salt selected from the group consisting of iron salt, Ti, and Co, Ni, Mn, Zn, Cu, Mg, and Al is reacted with an alkali, or the reaction mixture is subjected to an oxygen-containing atmosphere. A metal compound obtained by heating to a temperature of 30-90 ° C.

  [16] A metal compound obtained by attaching Ti and at least one metal salt selected from the group consisting of Co, Ni, Mn, Zn, Cu, Mg, and Al to the surface of the iron oxide particles.

  [17] A method of using the metal compound of [15] or [16] for producing an olivine type lithium iron phosphate compound.

[Olivine-type lithium iron phosphate compound]
The olivine-type lithium iron phosphate compound of the present invention has an average particle size of 500 nm or less, and has the following general formula:
_{Li x Fe y Ti p M q} PO 4
(Wherein 0 <x <2, 0 <y <1.5, p / y = 0.001 to 0.2, q / p = 0 to 10, M is Co, Ni, Mn, (At least one metal selected from the group consisting of Zn, Cu, Mg, and Al)
It is the olivine type lithium iron phosphate compound represented by these.

  The present invention is to provide an olivine-type lithium iron phosphate compound having a high capacity and capable of high-speed charging / discharging. Therefore, at least part of Fe is substituted with Ti, and particles having an average particle diameter of 500 nm or less are obtained. suggest. The conductivity is improved by substitution of Ti, and high capacity and high rate characteristics are made possible by using fine particles.

  The substitution amount can be arbitrarily set within the range of p / y = 0.001 to 0.2 and q / p = 0 to 10, but preferably p / y = 0.01 to 0.1, in particular 0.01 to 0.05, preferably q / p = 0 to 5. On the other hand, the molar ratio y of Fe can be arbitrarily set within the range of 0 <y <1.5, but usually 0.8 <y <1.2. The substitution metal must use Ti, and is at least one metal selected from the group consisting of Co, Ni, Mn, Zn, Cu, Mg, and Al.

  The combination of the substitutional metals Ti and M is not particularly limited, but Ti alone has a sufficient effect, but it is possible to further improve the characteristics by combining Ti-Co, Ti-Mn, Ti-Mg, and the like. is there. Further, Ti and a plurality of types of M can be combined, such as Ti— (Co + Ni), Ti— (Mg + Al).

  Ti has a good anti-sintering effect and can further promote the refinement of particles, but further, by substituting Fe of the olivine-type lithium iron phosphate compound in combination with the metal element M, It is also possible to improve the crystallinity of the compound and facilitate Fe redox (oxidation-reduction reaction).

  In order to satisfy both high capacity and high rate characteristics at the same time, the particle size of the olivine-type lithium iron phosphate compound needs to be 500 nm or less, preferably 10 to 200 nm.

It is preferable that BET value is 10 to 50 m ² / g, more preferably from 10 to 30 m ² / _g, preferably _{D 111} is 20.0～80.0Nm, more preferably 30. It is preferably 0 to 50.0 nm, and the coefficient of variation of the particle size distribution is preferably 0.5 or less, and more preferably 0.4 or less.

  The olivine-type lithium iron phosphate compound of the present invention may have various substances such as conductive substances on the particle surface. A typical conductive material is carbon.

[Method for producing olivine-type lithium iron phosphate compound]
ADVANTAGE OF THE INVENTION According to this invention, an iron source, a lithium source, and a phosphorus source are mixed and baked, The manufacturing method of the olivine type lithium iron phosphate compound characterized by the above-mentioned is provided. In this method, it is important that the iron source contains iron oxide particles containing a substitution element.

  The iron oxide particles are fine and can be prepared with precisely controlled particle size distribution. The present inventors pay attention to this point, and by including iron oxide particles containing a substitution element as an iron source, an olivine-type lithium iron phosphate compound having a very fine particle and a controlled particle size distribution is obtained. As a result, the present inventors succeeded in producing a non-aqueous electrolyte battery having excellent performance by using a positive electrode active material containing an olivine type lithium iron phosphate compound having a fine particle size distribution and a good particle size distribution.

(Iron source)
The iron source used in the present invention includes iron oxide particles. The iron oxide particles preferably have an average particle size of 500 nm or less, more preferably 300 nm or less, particularly 3 to 100 nm. From the iron oxide particles having an average particle diameter of about 5 nm, the olivine-type lithium iron phosphate compound having an average particle diameter of about 5 to 50 nm is used. From the iron oxide particles having an average particle diameter of about 300 nm, the olivine-type iron phosphate having about 100 to 500 nm is prepared. A lithium compound is obtained. The iron oxide particles also preferably have a coefficient of variation [= (standard deviation / average particle diameter)] of a particle diameter of 0.50 or less, and preferably have a BET specific surface area value of 10 to 150 m ² / g.

Examples of the iron oxide include iron monoxide (FeO), triiron tetroxide (Fe ₃ O ₄ ) such as magnetite, and diiron trioxide (Fe ₂ O ₃ ) such as hematite. Among these, triiron tetroxide (Fe ₃ O ₄ ) is particularly preferable. Since triiron tetroxide (Fe ₃ O ₄ ) can be prepared by a wet method, with relatively inexpensive materials and equipment, as fine particles and with a precisely controlled particle size distribution, the olivine type of the present invention Useful for producing lithium iron phosphate. In comparison with such diiron trioxide (Fe 2 _{O 3),} the oxygen content is low, reducing easily, can be obtained to prevent it particles sintered during firing. In addition, since fine particles can be obtained from fine Fe ₂ O ₃ or the like, it can be used to produce the olivine-type lithium iron phosphate of the present invention.

For example, iron oxide is produced by reacting an iron salt with an alkali and mixing, for example, an iron salt and an aqueous alkali solution, particularly an alkali hydroxide and / or an alkali carbonate, to produce iron hydroxide. Fe ₃ O ₄ obtained by heating (oxidation synthesis) a reaction product containing iron to a temperature of 30 to 90 ° C. in an oxygen-containing atmosphere (for example, atmospheric pressure) is preferable.

Examples of iron salts include iron sulfate, iron acetate, and iron chloride.
Examples of the alkali hydroxide include sodium hydroxide, potassium hydroxide, and aqueous ammonia. Examples of the alkali carbonate include sodium carbonate, potassium carbonate, and ammonium carbonate. Even if an alkali metal is used as the alkali, most of the alkali metal produced as a by-product of the neutralization reaction can be removed by washing with water, but an ammonium salt should be used to extremely reduce the alkali metal contamination. Is appropriate. In addition, fine particles can be obtained only with alkali hydroxide, but it is effective to use them mixed with alkali carbonate in order to obtain finer particles. In order to obtain fine single-phase iron oxide particles, a neutralization rate of 0.8 to 3.0 (where the neutralization rate is the alkali source used for neutralization relative to the molar equivalent of the acid source before neutralization) For example, when 20 mol of NaOH is used for 10 mol of MnSO ₄ , the neutralization rate is 20 / (10 × 2) = 1.0.) Temperature 30 to 90 ° C. It is appropriate to carry out the above oxidation synthesis within the range of

The iron source contains a metal other than iron as a replacement metal. Examples of the substitution metal include those described above.
The introduction of the substitution metal into the iron source uses, for example, iron oxide particles doped with a substitution metal (doping method) and / or iron oxide particles obtained by wet-treating the substitution metal (wet surface treatment method) as iron oxide particles. This can be achieved.

  The dope method (solid solution method) is a step of reacting an iron salt and a substituted metal salt with an alkali, particularly an alkali hydroxide and / or an alkali carbonate under heating in the step of preparing iron oxide particles by the above-described oxidation synthesis. The substituted metal-containing oxide is obtained, or the salt of the substituted metal is reacted with an alkali, particularly an alkali hydroxide and / or an alkali carbonate, together with an iron salt to obtain a hydroxide, and the hydroxide-containing mixture is obtained as 30 It is a method for producing a metal oxide by heating to a temperature of ˜90 ° C. and blowing an oxygen-containing gas into this mixture. In this case, as a doping method, it is possible to mix the solution of the substituted metal salt with the iron salt solution from the beginning. An inclined doping method is also effective. By using the obtained raw material by this method, uniform and fine substituted olivine type lithium iron phosphate particles can be obtained.

  The wet surface treatment method is a method in which a substitution metal salt is attached to the surface of iron oxide particles by mixing a solution of the substitution metal salt with a liquid containing iron oxide particles obtained by the above-described oxidation synthesis. As the surface treatment method, the substitution metal solution is added at a constant rate while stirring the suspension of iron oxide particles after completion of oxidation. The rate of addition is not limited, but is preferably about 0.5 to 3 hours. Here, the pH of the suspension is preferably 5 or more. In addition, in the case of an element that does not easily adhere to the particle surface alone, it is also effective to add a plurality of metal elements in a mixture. For example, the inventors have confirmed that Fe and Ti and Co and Ti are mixed and added to uniformly adhere to the surface of the oxidized particles.

  Examples of the metal salt used in the above method include sulfates, hydrochlorides, or organic acid salts such as acetates. From the viewpoint of preventing impurities from remaining in the obtained positive electrode active material, it is preferable to use an organic acid salt such as acetate, a sulfate, or the like.

  Either method is very reactive, easy to perform, uniform and fine substitution compared to the method in which the substitution metal is mixed together when mixing the iron source with the phosphorus source and the lithium source. It is possible to obtain olivine type lithium iron phosphate particles.

(Lithium source and phosphorus source)
A lithium source and a phosphorus source are mixed with the above iron source and fired to obtain olivine type lithium iron phosphate.

  Examples of the lithium source include lithium carbonate, lithium hydroxide, and lithium phosphate. Examples of the phosphorus source include phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lithium dihydrogen phosphate, and lithium phosphate. .

(Mixing process)
The mixing method is not particularly limited, and may be wet mixing or dry mixing. As an apparatus, it is appropriate to use a planetary ball mill, a jet mill, a magnetic stirrer, or the like.

(Baking process)
In the firing step, by supplying thermal energy to the mixture of raw materials, the mixture is converted into a thermodynamically stable olivine-type lithium iron phosphate compound, and impurities are vaporized and removed. This is a process for producing fine particles.

  Firing is performed in an inert gas atmosphere or a reducing atmosphere. Examples of the inert gas include nitrogen, helium, neon, and argon. Examples of the reducing atmosphere include hydrogen, lower alcohols, for example, reducing compounds such as methanol and ethanol, mixtures of reducing compounds and inert gases, and the like. When a mixture of a reducing compound and an inert gas is used, the mixing ratio (volume ratio) of the reducing compound and the inert gas is not particularly limited.

  The firing temperature is preferably 400 to 800 ° C. It is possible to obtain sufficient crystallinity even by one-step firing. In addition, the crystallinity can be further improved by performing a two-stage firing process including a temporary firing process and a main firing process. The pre-baking is usually performed at a temperature of 200 to 400 ° C., and the main baking is usually performed at a temperature of 400 to 800 ° C., preferably 500 to 800 ° C., more preferably 500 to 750 ° C.

  Further, before firing, various conductive materials (for example, carbon) or precursors thereof are mixed and fired in an inert gas atmosphere or a reducing atmosphere, so that the surface of the olivine type lithium iron phosphate particles is so treated. It is possible to obtain a very fine positive electrode active material in which a conductive material is present. In particular, when a carbon source is mixed, single-phase olivine-type lithium iron phosphate can be obtained by using, for example, nitrogen gas alone without using a reducing gas.

Examples of the conductive substance include carbon. In particular, carbon is advantageous in terms of easy availability and handling.
The amount of carbon source added is not limited, but it goes without saying that the carbon content remaining after firing does not become excessive as the positive electrode, preferably 20% by weight or less, particularly 1 to 20%, based on the weight of the positive electrode active material. It is desirable to add in the range of wt%, more preferably 1 to 10 wt%.

  The carbon source includes at least one of carbon particles and a carbon precursor that changes into conductive carbon by firing. When a carbon precursor is used as the carbon source, the particle surface can be coated flat with carbon, and a positive electrode active material having a relatively low surface area can be produced.

Known carbon particles can be used without limitation, and examples thereof include carbon black such as acetylene black; fullerene; carbon nanotubes and the like.
Examples of the carbon precursor include saccharides such as polyvinyl alcohol, polyolefins, polyacrylonitrile, cellulose, starch, glucose and granulated sugar, and natural organic polymer compounds (particularly water-soluble compounds); acrylonitrile, divinylbenzene, Examples thereof include polymerizable monomers such as vinyl acetate (particularly unsaturated organic compounds having a carbon-carbon double bond).

  The carbon source may be added to the raw material at any stage of the baking process, for example, may be added before the preliminary baking, or may be added after the preliminary baking and before the main baking. It may be added before and at both stages. Further, by adding a carbon source, it is possible to obtain an olivine single phase even when firing with only an inert gas.

[Positive electrode active material]
The positive electrode active material of the present invention needs to contain olivine-type lithium iron phosphate as a main component, but as a component other than olivine-type lithium iron phosphate, it should contain a conductive material such as carbon. Can do. The blending ratio of other components needs to be 30% or less of the positive electrode active material.

The average particle diameter of the positive electrode active material is preferably 500 nm or less, more preferably 10 to 200 nm. In the case of an olivine-type positive electrode active material with low conductivity, if the average particle size is too large, sufficient capacity cannot be obtained. The positive electrode active material preferably has a coefficient of variation in particle size of 0.50 or less, particularly 0.40 or less, and preferably has a BET specific surface area value of 10 to 50 m ² / g.

[Nonaqueous electrolyte battery]
(Battery structure)
An example of a nonaqueous electrolyte battery using the positive electrode active material of the present invention will be described with reference to the accompanying drawings.
FIG. 28 is a cross-sectional view schematically showing the battery. In this figure, a non-aqueous electrolyte battery 1 generally includes a negative electrode member 2 that functions as an external negative electrode of the battery, a positive electrode member 3 that functions as an external positive electrode of the battery, a negative electrode current collector 4, a negative electrode active material between the two members. The material layer 5, the separator 8, the positive electrode active material layer 7, and the positive electrode current collector 6 are provided in this order. The negative electrode member 2 has a substantially cylindrical shape, and is configured to accommodate the negative electrode current collector 4 and the negative electrode active material 5 therein. On the other hand, the positive electrode member 3 also has a substantially cylindrical shape, and is configured to accommodate the positive electrode current collector 6 and the positive electrode active material layer 7 therein. The dimensions of the positive electrode member 3 and the separator 8 in the radial direction are set slightly larger than those of the negative electrode member 2 so that the peripheral end portions of the negative electrode member 2 and the peripheral end portions of the separator 8 and the positive electrode member 3 overlap each other. It has become. The space inside the battery is filled with a non-aqueous electrolyte 9, and a sealing material 10 is applied to the overlapping portions of the peripheral ends of the negative electrode member 2, the separator 8, and the positive electrode member 3 to keep the inside of the battery airtight. Yes.

  The negative electrode comprises a negative electrode member 2 as an external negative electrode, and a negative electrode current collector 4 in contact therewith and a negative electrode active material layer 5 on the negative electrode current collector. As the negative electrode current collector, for example, nickel foil, copper foil or the like is used. As the negative electrode active material layer, a layer capable of doping / de-doping lithium is used. Specifically, metallic lithium, lithium alloy, conductive polymer doped with lithium, layered compound (carbon material, metal oxide, etc. ) Etc. As the binder contained in the negative electrode active material layer, a known resin material or the like that is usually used as a binder for the negative electrode active material layer of this type of non-aqueous electrolyte battery can be used. In particular, since the metal lithium foil can be used not only as the negative electrode active material but also as the negative electrode current collector, the battery structure can be simplified by using the metal lithium foil for the negative electrode.

  The positive electrode comprises a positive electrode member 3 as an external positive electrode, and a positive electrode current collector 6 in contact therewith, and a positive electrode active material layer 7 on the positive electrode current collector. The positive electrode active material of the present invention described above is used as the positive electrode active material. For example, an aluminum foil or the like is used as the positive electrode current collector. As the binder contained in the positive electrode active material layer, it is usually used as a binder for the positive electrode active material layer of this type of non-aqueous electrolyte battery such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and the like. A known resin material or the like can be used. A conductive material can be blended in the positive electrode active material layer in order to improve conductivity. Examples of the conductive material include graphite and acetylene black.

  The separator 8 separates the positive electrode and the negative electrode, and a known material that is usually used as a separator for this type of non-aqueous electrolyte battery can be used. For example, a polymer film such as polypropylene, polyethylene carbonate, etc. A porous membrane or the like is used. In addition, it is desirable that the thickness of the separator is as thin as possible from the relationship between lithium ion conductivity and energy density. Specifically, the thickness of the separator is preferably 50 μm or less, for example.

As the sealing material 10, a known resin material or the like that is normally used as a sealing material for the positive electrode active material layer of this type of non-aqueous electrolyte battery can be used.
As the non-aqueous electrolyte, not only a liquid electrolyte but also various forms such as a solid electrolyte and a gel electrolyte containing a solvent can be used. As the liquid electrolyte, a solution in which an electrolyte is dissolved in an aprotic nonaqueous solvent is used. Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate, and dipropyl carbonate, γ-butyllactone, sulfolane, 1, Examples include 2-dimethoxyethane, 1,2-diethoxyethane, 2-methyltetrahydrofuran, 3-methyl-1,3-dioxolane, methyl propionate, and methyl butyrate. In particular, from the viewpoint of voltage stability, it is preferable to use cyclic carbonates such as ethylene carbonate, propylene carbonate, and vinylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and dipropyl carbonate. Moreover, such a non-aqueous solvent may be used individually by 1 type, and may be used in mixture of 2 or more types. As the electrolyte, for example, lithium salts such as LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , and LiN (CF ₃ SO ₂ ) ₂ can be used. Among these lithium salts, it is preferable to use LiPF ₆ or LiBF ₄ . Examples of the solid electrolyte include inorganic solid electrolytes such as lithium nitride and lithium iodide; organic polymer electrolytes such as poly (ethylene oxide), poly (methacrylate), and poly (acrylate). Furthermore, the material for forming the gel electrolyte can be used without particular limitation as long as it is a material capable of gelling by absorbing the liquid electrolyte. For example, poly (vinylidene fluoride), vinylidene fluoride / Examples thereof include fluorine-containing polymers such as hexafluoropropylene copolymers.

(Battery manufacturing method)
The nonaqueous electrolyte battery using the positive electrode active material of the present invention is manufactured as follows, for example.
First, the negative electrode manufacturing method will be described. A negative electrode active material and a binder are dispersed in a solvent to prepare a slurry. The obtained slurry is uniformly applied on a current collector and dried to form a negative electrode active material layer. The obtained laminate including the negative electrode current collector and the negative electrode active material layer is accommodated in the negative electrode member so that the negative electrode current collector and the inner surface of the negative electrode member are in contact with each other to form a negative electrode. Further, as described above, the metal lithium foil can be used as it is as the negative electrode active material and the negative electrode active material.

  Next, the manufacturing method of a positive electrode is demonstrated. A positive electrode active material, a conductive material, and a binder of the present invention are dispersed in a solvent to prepare a slurry. The slurry is uniformly applied on the current collector and dried to form a positive electrode active material layer. The obtained laminate of the positive electrode current collector and the positive electrode active material layer is accommodated in the positive electrode member so that the positive electrode current collector and the inner surface of the positive electrode member are in contact with each other, thereby forming a positive electrode.

When a nonaqueous electrolyte is used, it is prepared by dissolving an electrolyte salt in a nonaqueous solvent.
The negative electrode and the positive electrode manufactured as described above are overlapped so that a separator is interposed between the negative electrode active material layer and the positive electrode active material layer, filled with a nonaqueous electrolyte, and the inside of the battery is sealed with a sealing material. By doing so, a non-aqueous electrolyte battery is completed.

  The shape of the nonaqueous electrolyte battery of the present invention is not particularly limited, and can be a cylindrical shape, a square shape, a coin shape, a button shape, or the like, and various types such as a thin shape and a large size are available. Can be sized. The present invention can be applied to both a primary battery and a secondary battery.

[Example]
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.
In the following examples, analysis of iron oxide, positive electrode active material, and nonaqueous electrolyte battery was performed by the following method.

(X-ray diffraction)
X-ray diffraction measurement was performed using CoKα Rigaku RINT 2200V (manufactured by Rigaku Corporation). In this specification, D ₁₁₁ is the following Scherrer formula from the half-value width of the diffraction peak corresponding to the crystal plane of the 111 plane:
L = Kλ / (βcosθ)
(In the formula, L is a crystallite diameter, K is a constant (= 0.9), λ is an X-ray wavelength, β is a half-value width, and θ is a reflection angle.)
The crystallite diameter determined according to

(Specific surface area)
The specific surface area measurement was performed using a fully automatic surface area measuring device Multisorb 12 (manufactured by Yuasa Ionics Co., Ltd.) according to the BET method.

(Metal composition analysis)
The metal composition analysis was measured by ICP emission spectroscopic analysis (ICP emission spectroscopic analyzer SPS1500VR Seiko Instruments Inc.) and calculated by the molar ratio with respect to Fe.

(Carbon content)
The carbon content was measured using CARBON ANALYZER (HORIBA EMIA-221V).

(Particle size)
For the particle size, 200 particles observed randomly with TEM (transmission electron microscope H-7600 manufactured by Hitachi) or SEM (scanning electron microscope DS130 manufactured by Topcon Electron Beam Service Co., Ltd.) were randomly selected. The average particle size and standard deviation of the measured values were calculated, and this average value was taken as the particle size. The variation coefficient of the particle diameter is a value obtained by dividing the standard deviation thus obtained by the average particle diameter.

(1) Manufacture of Ti-doped iron oxide 40 L of an aqueous solution containing 55.2 mol of NaOH was charged into a 60 L reaction vessel, and the gas was replaced with nitrogen gas, and kept at 80 ° C. To this, 20 L of an aqueous solution containing 6 mol of FeSO ₄ , 6 mol of Fe ₂ (SO ₄ ) ₃ and 0.36 mol of Ti (SO ₄ ) _{2 was} added while stirring with nitrogen, and mixed at 80 ° C. for 3 hours. . The obtained suspension was filtered, washed and dried to obtain fine particle Ti-doped iron oxide.

The specific surface area of the obtained sample was measured by the BET method. The BET value of the obtained sample was 87.9 m ² / g.
A TEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The average particle size of the obtained sample was 10 nm.
X-ray diffraction measurement was performed on the obtained particles. FIG. 2 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be a magnetite single phase.

(2) Method for producing LiFe _0.98 Ti _0.02 PO _{4 Using} the iron oxide obtained in (1) above as a raw material, olivine-type lithium iron phosphate was synthesized. Ti-doped iron oxide obtained in (1) 0.05 mol (0.15 mol as a metal content), Li ₂ CO ₃ 0.079 mol, (NH ₄ ) ₂ HPO ₄ 0.153 mol and glucose 4 g in an 80 mL planetary ball mill container Then, 20 mL of pure water was further added and mixed at 250 rpm for 12 hours. After drying at 120 ° C., the mixture was pulverized in an agate mortar and fired at 650 ° C. for 6 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.98 Ti _0.02 PO ₄ . The BET value of the obtained sample was 17.5 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 57 nm and a variation coefficient of 0.27.

X-ray diffraction measurement was performed on the obtained particles. FIG. 4 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

(3) Production of coin cell Using the positive electrode active material obtained in (2), a lithium secondary battery was produced. Using the obtained sample, polytetrafluoroethylene as the binder, and acetylene black as the conductive material, positive electrode active material: conductive material: binder = 70: 25 (total carbon content, ie, pre-treated carbon (As the amount of acetylene black added to the amount of glucose) Was used as a positive electrode pellet.

A coin cell was produced using the positive electrode pellet. As the counter electrode of the positive electrode pellet, a lithium foil having a diameter of 1.5 mm and a thickness of 0.15 mm was used. As the separator, a porous polyethylene sheet having a diameter of 22 mm and a thickness of 0.02 mm was used. As the nonaqueous electrolyte solution, a solution obtained by dissolving LiPF ₆ at a concentration of about 1 mol / liter in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1: 1 was used. These components were incorporated into a stainless steel positive electrode container and a negative electrode lid and sealed with a gasket to produce a coin-type measurement cell shown in FIG. 5 having a thickness of 2 mm and a diameter of 32 mm (2032 type). In addition, a series of battery assembly operations were performed in a dry box having a dew point of −90 ° C. or less equipped with an argon purification device.

  A charge / discharge test was conducted on the simple lithium secondary battery thus obtained. The charge / discharge test was conducted at 25 ° C. with a potential range of 2000 to 4500 mV, a rate of 0.2, 1, 5C, and C.I. CC. V performed. The initial charge / discharge characteristics at a rate of 0.2 C are shown in FIG. 6 (in the figure, “Chg” represents charge and “Dis” represents discharge). Table 2 shows the initial charge / discharge capacity at each rate.

(1) Manufacture of Ti and Mn doped iron oxide A 60 L reaction vessel was charged with 40 L of an aqueous solution containing 24 mol of NaOH and 12 mol of Na ₂ CO ₃ , nitrogen gas was passed through and replaced, and the temperature was maintained at 60 ° C. To this, 20 L of an aqueous solution containing 18 mol of FeSO _4, 0.9 mol of Fe ₂ (SO ₄ ) _3, 0.40 mol of Ti (SO ₄ ) _{2 and} 0.40 mol of MnSO ₄ was added while stirring with nitrogen. A suspension containing iron oxide particles was prepared and mixed at 60 ° C. for 60 minutes. Next, the air was aerated at 10 L / min while maintaining the temperature at 60 ° C., and an oxidation reaction was performed for 2 hours. The obtained suspension was filtered, washed and dried to obtain fine-particle iron oxide. The specific surface area of the sample was measured by the BET method. The BET value of the obtained sample was 29.5 m ² / g. A TEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The average particle size of the obtained sample was 65 nm.

(2) Production method of LiFe _0.96 Ti _0.02 Mn _0.02 PO _{4 Using} the iron oxide obtained in (1) above as a raw material, olivine-type lithium iron phosphate was synthesized. Ti and Mn doped iron oxide obtained in (1) 0.05 mol (0.15 mol as metal content), Li ₂ CO ₃ 0.080 mol, (NH ₄ ) ₂ HPO ₄ 0.15 mol and glucose 5 g in 80 mL planetary Into a ball mill container, 20 mL of pure water was further added and mixed at 250 rpm for 24 hours. After drying at 150 ° C., the mixture was pulverized in an agate mortar and fired at 650 ° C. for 12 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.96 Ti _0.02 Mn _0.02 PO ₄ . The BET value of the obtained sample was 21.5 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The average particle diameter of the obtained sample was 62 nm, and the coefficient of variation was 0.39.

X-ray diffraction measurement was performed on the obtained particles. FIG. 9 shows an X-ray diffraction pattern of the obtained particles.
From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

(1) Manufacture of Ti surface-treated iron oxide 40 L of an aqueous solution containing 52.8 mol of NaOH was charged into a 60 L reaction vessel, and the gas was replaced with nitrogen gas, and kept at 80 ° C. To this, 20 L of an aqueous solution containing 6 mol of FeSO ₄ and 6 mol of Fe ₂ (SO ₄ ) ₃ was added with nitrogen aeration and stirring, and mixed at 80 ° C. for 3 hours. The obtained suspension was filtered, washed and dried to obtain fine-particle iron oxide. The specific surface area of the sample was measured by the BET method. The BET value of the obtained sample was 74.2 m ² / g.

The obtained suspension after oxidation was mixed uniformly, and 6 L (1.8 mol as Fe) was charged into a 15 L reaction vessel. While mixing at room temperature, 1 L of an aqueous solution in which 0.018 mol of Ti (SO ₄ ) ₂ was dissolved was added dropwise over 1 hour. The obtained suspension was filtered, washed and dried to obtain fine-particle iron oxide. A TEM photograph of the obtained sample is shown in FIG.

(2) Method for producing LiFe _0.99 Ti _0.01 PO ₄ Olivine-type lithium iron phosphate was synthesized from the surface-treated iron oxide obtained in (1) above. (1) obtained in iron oxide 0.05 mol (0.15 mol as the metal _{component), Li 2 CO 3 0.079mol,} (NH 4) 2 placed HPO 4 0.162 mol and glucose 4g in 80mL planetary ball mill, Further, 20 mL of pure water was added and mixed at 250 rpm for 12 hours. After drying at 120 ° C., the mixture was pulverized in an agate mortar and fired at 650 ° C. for 12 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.99 Ti _0.01 PO ₄ . The obtained sample had a BET value of 15.3 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The average particle diameter of the obtained sample was 76 nm, and the coefficient of variation was 0.35.

X-ray diffraction measurement was performed on the obtained particles. FIG. 12 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

(1) Manufacture of Ti and Co surface-treated iron oxide A 60 L reaction vessel was charged with 40 L of an aqueous solution containing 23 mol of NaOH and 11 mol of Na ₂ CO ₃ , replaced with nitrogen gas, and maintained at 60 ° C. . To this, 20 L of an aqueous solution containing 18 mol of FeSO ₄ and 0.9 mol of Fe ₂ (SO ₄ ) ₃ was added with nitrogen aeration and stirring to obtain a suspension containing iron hydroxide particles at 60 ° C. Mix for 60 minutes. Next, the air was aerated at 10 L / min while maintaining the temperature at 60 ° C., and an oxidation reaction was performed for 2 hours. The obtained suspension was filtered, washed and dried to obtain fine-particle iron oxide. The specific surface area of the sample was measured by the BET method. The BET value of the obtained sample was 27.4 m ² / g.

The obtained suspension after oxidation was mixed uniformly, 6 L (1.8 mol as Fe) was charged into a 15 L reaction vessel, and 1 L of an aqueous solution in which 0.54 mol of Na ₂ CO ₃ was dissolved was added. , Mixed. While mixing at room temperature, 1 L of an aqueous solution in which 0.036 mol of Ti (SO ₄ ) ₂ and 0.018 mol of CoSO ₄ .7H ₂ O were dissolved was added dropwise over 1 hour. The obtained suspension was filtered, washed and dried to obtain fine-particle iron oxide.

_{(2) LiFe 0.97} Ti at _{0.02 Co 0.01} PO ₄ of the method for manufacturing the surface-treated iron oxide obtained in (1) was synthesized olivine type lithium iron phosphate as a raw material. Into an 80 mL planetary ball mill container, 0.05 mol of iron oxide obtained in (1) (0.15 mol as a metal content), 0.079 mol of Li ₂ CO ₃ , 0.15 mol of (NH ₄ ) ₂ HPO ₄ and 6 g of glucose are placed. Further, 20 mL of pure water was added and mixed at 250 rpm for 24 hours. After drying at 150 ° C., the mixture was pulverized in an agate mortar and fired at 700 ° C. for 4 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.97 Ti _0.02 Co _0.01 PO ₄ . The BET value of the obtained sample was 13.5 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 101 nm and a coefficient of variation of 0.39.

X-ray diffraction measurement was performed on the obtained particles. FIG. 14 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

(1) Production of Ti and Mn surface-treated iron oxide In the same manner as in Example 3, the obtained suspension after oxidation was mixed uniformly, and 6 L (1.8 mol as Fe) was mixed with 15 L. 1 L of an aqueous solution in which 0.54 mol of Na ₂ CO ₃ was dissolved was added and mixed. While mixing at room temperature, 1 L of an aqueous solution in which 0.018 mol of Ti (SO ₄ ) ₂ and 0.036 mol of MnSO ₄ were dissolved was added dropwise over 1 hour. The obtained suspension was filtered, washed and dried to obtain fine-particle iron oxide.

_{(2) LiFe 0.97} Ti at _{0.01 Mn 0.02} PO ₄ of the method for manufacturing the surface-treated iron oxide obtained in (1) was synthesized olivine type lithium iron phosphate as a raw material. The surface-treated iron oxide 0.05 mol (0.15 mol as a metal content) obtained in (1), Li ₂ CO ₃ 0.079 mol, (NH ₄ ) ₂ HPO ₄ 0.153 mol and glucose 4 g in 80 mL planetary Into a ball mill container, 20 mL of pure water was further added and mixed at 250 rpm for 6 hours. After drying at 120 ° C., the mixture was pulverized in an agate mortar and fired at 650 ° C. for 6 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.99 Ti _0.01 PO ₄ . The obtained sample had a BET value of 17.4 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 65 nm and a coefficient of variation of 0.34.

X-ray diffraction measurement was performed on the obtained particles. FIG. 16 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

(1) Production of Ti surface-treated iron oxide In the same manner as in Example 3, the obtained suspension after oxidation was mixed uniformly, and 6 L (1.8 mol as Fe) was reacted in 15 L. The container was charged and 1 L of an aqueous solution in which 0.54 mol of Na ₂ CO ₃ was dissolved was added and mixed. While mixing at room temperature, 1 L of an aqueous solution in which 0.178 mol of Ti (SO ₄ ) ₂ was dissolved was added dropwise over 1 hour. The obtained suspension was filtered, washed and dried to obtain surface-treated iron oxide.

(2) Method for producing LiFe _0.91 Ti _0.09 PO _{4 Using} the surface-treated iron oxide obtained in (1) above as a raw material, olivine-type lithium iron phosphate was synthesized. Put the iron oxide 0.05 mol (0.15 mol as a metal content) obtained in (1), Li ₂ CO ₃ 0.079 mol, (NH ₄ ) ₂ HPO ₄ 0.158 mol and glucose 5 g in an 80 mL planetary ball mill container, Further, 20 mL of pure water was added and mixed at 250 rpm for 24 hours. After drying at 120 ° C., the mixture was pulverized in an agate mortar and fired at 750 ° C. for 3 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.91 Ti _0.09 PO ₄ . The BET value of the obtained sample was 22.9 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 64 nm and a coefficient of variation of 0.39.

X-ray diffraction measurement was performed on the obtained particles. FIG. 18 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

(1) Production of Ti and Mn surface-treated iron oxide In the same manner as in Example 3, the obtained suspension after oxidation was mixed uniformly, and 6 L (1.8 mol as Fe) was mixed with 15 L. 1 L of an aqueous solution in which 0.54 mol of Na ₂ CO ₃ was dissolved was added and mixed. While mixing at room temperature, 1 L of an aqueous solution in which 0.0095 mol of Ti (SO ₄ ) _{2 and} 0.095 mol of MnSO ₄ were dissolved was added dropwise over 1 hour. The obtained suspension was filtered, washed and dried to obtain surface-treated iron oxide.

_{(2) LiFe 0.945} in _Ti 0.005 _{Mn 0.05} PO ₄ of the method for manufacturing the surface-treated iron oxide obtained in (1) was synthesized olivine type lithium iron phosphate as a raw material. Into an 80 mL planetary ball mill container, 0.05 mol of iron oxide obtained in (1) (0.15 mol as a metal content), 0.079 mol of Li ₂ CO ₃ , 0.153 mol of (NH ₄ ) ₂ HPO ₄ and 4 g of glucose are placed. Further, 20 mL of pure water was added and mixed at 250 rpm for 12 hours. After drying at 120 ° C., the _mixture was pulverized in an agate mortar and fired at 650 ° C. for 6 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.945 Ti _0.005 Mn _0.05 PO ₄ . The BET value of the obtained sample was 18.3 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 94 nm and a coefficient of variation of 0.38.

X-ray diffraction measurement was performed on the obtained particles. FIG. 20 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

Comparative Example 1

(1) Production of iron oxide 40 L of an aqueous solution containing 52.8 mol of NaOH was charged into a 60 L reaction vessel, and nitrogen gas was passed through to replace it, and the temperature was maintained at 80 ° C. To this, 20 L of an aqueous solution containing 6 mol of FeSO ₄ and 6 mol of Fe ₂ (SO ₄ ) ₃ was added with nitrogen aeration and stirring, and mixed at 80 ° C. for 3 hours. The obtained suspension was filtered, washed and dried to obtain fine particle magnetite (Fe ₃ O ₄ ). The specific surface area of the sample was measured by the BET method. The BET value of the obtained sample was 74.2 m ² / g. A TEM photograph of the obtained sample is shown in FIG.

(2) LiFePO ₄ in the manufacturing method described above: (1) iron oxide obtained in _(Fe 3 _{O 4)} was synthesized olivine type lithium iron phosphate as a raw material. Add 0.05 mol of iron oxide obtained in (1), 0.079 mol of Li ₂ CO ₃ , 0.15 mol of (NH ₄ ) ₂ HPO ₄ and 4 g of glucose into an 80 mL planetary ball mill container, and then add 20 mL of pure water. And mixed at 250 rpm for 12 hours. After drying at 120 ° C., the mixture was pulverized in an agate mortar and fired at 650 ° C. for 6 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFePO ₄ . The BET value of the obtained sample was 12.5 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 80 nm and a coefficient of variation of 0.32.

X-ray diffraction measurement was performed on the obtained particles. FIG. 23 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

(1) Production method of LiFe _0.95 Ti _0.05 PO ₄ 80 mL planetary ball mill container containing 0.1 mol of iron oxalate, 0.0053 mol of titanium isopropoxysite, 0.107 mol of hydrogen diammonium phosphate and 0.056 mol of lithium carbonate In addition, 30 mL of pure water was added and mixed at 250 rpm for 12 hours. After drying at 120 ° C., the mixture was pulverized in an agate mortar and baked at 650 ° C. for 6 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.95 Ti _0.05 PO ₄ . The obtained sample had a BET value of 6.6 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 125 nm and a coefficient of variation of 0.61.

X-ray diffraction measurement was performed on the obtained particles. FIG. 25 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

Comparative Example 2

(1) Production of Ti surface-treated iron oxide In the same manner as in Example 3, the obtained suspension after oxidation was mixed uniformly, and 6 L (1.8 mol as Fe) was reacted in 15 L. The container was charged and 1 L of an aqueous solution in which 0.54 mol of Na ₂ CO ₃ was dissolved was added and mixed. While mixing at room temperature, 1 L of an aqueous solution in which 0.45 mol of Ti (SO ₄ ) ₂ was dissolved was added dropwise over 1 hour. The obtained suspension was filtered, washed and dried to obtain fine-particle iron oxide.

₍₂₎ In LiFe _{0.8 Ti} 0.2 PO ₄ of the method for manufacturing the iron oxide obtained in (1) was synthesized olivine type lithium iron phosphate as a raw material. Add 0.05 mol of iron oxide obtained in (1), 0.079 mol of Li ₂ CO ₃ , 0.15 mol of (NH ₄ ) ₂ HPO ₄ and 4 g of glucose into an 80 mL planetary ball mill container, and then add 20 mL of pure water. And mixed at 250 rpm for 12 hours. After drying at 120 ° C., the mixture was pulverized in an agate mortar and fired at 650 ° C. for 6 hours in an N ₂ atmosphere to obtain a positive electrode active material LiFe _0.8 Ti _0.2 PO ₄ . The BET value of the obtained sample was 20.9 m ² / g. An SEM photograph of the obtained sample is shown in FIG. The particle diameter was calculated from an average value obtained by randomly measuring 200 particles from a TEM photograph. The obtained sample had an average particle size of 62 nm and a coefficient of variation of 0.48.

X-ray diffraction measurement was performed on the obtained particles. FIG. 27 shows an X-ray diffraction pattern of the obtained particles. From the X-ray diffraction pattern, it was confirmed to be an olivine type lithium iron phosphate single phase.
Table 1 shows the composition analysis result, BET value, _D111, and carbon content by ICP analysis.

  In the same manner as in Example 1, a coin cell was assembled and a charge / discharge test was performed. Table 2 shows the initial charge / discharge capacity.

  Examples of the nonaqueous electrolyte battery using the positive electrode active material of the present invention include lithium secondary batteries such as metal lithium batteries, lithium ion batteries, and lithium polymer batteries.

2 is a TEM photograph of iron oxide particles produced in Example 1. FIG. 2 is an X-ray diffraction diagram of iron oxide produced in Example 1. FIG. 2 is a SEM photograph of lithium iron phosphate produced in Example 1. 1 is an X-ray diffraction pattern of lithium iron phosphate produced in Example 1. FIG. It is the schematic of the coin battery used in the Example. 4 is a graph showing the results of a charge / discharge test for the coin battery produced in Example 1. FIG. 4 is a TEM photograph of iron oxide particles produced in Example 2. 2 is a SEM photograph of lithium iron phosphate produced in Example 2. 2 is an X-ray diffraction pattern of lithium iron phosphate produced in Example 2. FIG. 4 is a TEM photograph of post-surface-treated iron oxide particles produced in Example 3. 4 is a SEM photograph of lithium iron phosphate produced in Example 3. 4 is an X-ray diffraction pattern of lithium iron phosphate produced in Example 3. FIG. 4 is a SEM photograph of lithium iron phosphate produced in Example 4. 4 is an X-ray diffraction pattern of lithium iron phosphate produced in Example 4. FIG. 4 is a SEM photograph of lithium iron phosphate produced in Example 5. 6 is an X-ray diffraction pattern of lithium iron phosphate produced in Example 5. FIG. 4 is a SEM photograph of lithium iron phosphate produced in Example 6. 6 is an X-ray diffraction pattern of lithium iron phosphate produced in Example 6. FIG. 4 is a SEM photograph of lithium iron phosphate produced in Example 7. 6 is an X-ray diffraction pattern of lithium iron phosphate produced in Example 7. FIG. 4 is a TEM photograph of iron oxide particles produced in Comparative Example 1. 2 is a SEM photograph of lithium iron phosphate produced in Comparative Example 1. 2 is an X-ray diffraction pattern of lithium iron phosphate produced in Comparative Example 1. FIG. 4 is a SEM photograph of lithium iron phosphate produced in Comparative Example 8. 6 is an X-ray diffraction pattern of lithium iron phosphate produced in Comparative Example 8. FIG. 4 is a SEM photograph of lithium iron phosphate produced in Comparative Example 2. 3 is an X-ray diffraction pattern of lithium iron phosphate produced in Comparative Example 2. FIG. It is sectional drawing which shows the outline of a nonaqueous electrolyte battery.

Claims (15)

The average particle size is 500 nm or less, and the following general formula:
_{Li x Fe y Ti p M q} PO 4
(Wherein 0 <x <2, 0 <y <1.5, p / y = 0.001 to 0.2, q / p = 0 to 10, M is Co, Ni, Mn, (At least one metal selected from the group consisting of Zn, Cu, Mg, and Al)
An olivine-type lithium iron phosphate compound represented by:
Variation coefficient of particle size distribution is 0.5 or less, BET value is 10 to 50 m ² / g, was determined from the half value width of the X-ray diffraction peak corresponding to the crystal plane 111 plane according to Scherrer's formula crystals olivine type lithium iron phosphate compounds child diameter _{(D 111)} is characterized in that it is a 20.0～80.0Nm.   The olivine-type lithium iron phosphate compound according to claim 1, having a carbon content of 0.1 to 10%.   The method for producing an olivine-type lithium iron phosphate compound according to claim 1, wherein an iron source, a lithium source and a phosphorus source containing substituted metal-containing iron oxide particles having an average particle diameter of 500 nm or less are mixed and calcined.   4. The method of claim 3, wherein the iron source comprises iron oxide particles doped with a substitution metal and / or iron oxide particles wet-treated with a substitution metal.   The method according to claim 3, wherein the replacement metal is at least one metal element selected from the group consisting of Ti and Co, Ni, Mn, Zn, Cu, Mg, and Al.   The method according to claim 3, wherein the iron oxide particles are obtained by reacting an iron salt with an alkali.   The method of claim 3, wherein the iron oxide particles are magnetite. The method of claim 6 , wherein the alkali is an alkali hydroxide and / or an alkali carbonate.   The method according to claim 3, wherein an iron source, a lithium source and a phosphorus source containing carbon oxide and / or a carbon precursor containing substituted metal-containing iron oxide particles having an average particle diameter of 500 nm or less are mixed and calcined.   The method according to any one of claims 3 to 9, wherein the firing is performed in an inert gas atmosphere or a reducing atmosphere. Performing firing in _{an N 2} atmosphere, The method of claim 10.   A positive electrode active material comprising the olivine-type lithium iron phosphate compound according to claim 1 or 2 or the olivine-type lithium iron phosphate compound obtained by the method according to any one of claims 3 to 11.   The nonaqueous electrolyte battery which has a positive electrode containing the positive electrode active material of Claim 12.   An iron salt and Ti and at least one metal salt selected from the group consisting of Co, Ni, Mn, Zn, Cu, Mg and Al are reacted with an alkali or the reaction mixture is reacted under an oxygen-containing atmosphere. The method to manufacture the olivine type lithium iron phosphate compound of Claim 1 using the metal compound obtained by heating to the temperature of -90 degreeC.   Claims using a metal compound obtained by attaching a salt of at least one metal selected from the group consisting of Ti and Co, Ni, Mn, Zn, Cu, Mg and Al to the surface of the iron oxide particles. 1. A method for producing an olivine-type lithium iron phosphate compound.