JP6357193B2 - Polyanionic positive electrode active material and method for producing the same - Google Patents

Description

  The present invention relates to a polyanionic positive electrode active material in which carbon derived from a carbon source and zinc oxide and / or aluminum oxide are supported on the particle surface of a polyanion material, and a method for producing the same.

Secondary batteries such as lithium ion secondary batteries and sodium ion secondary batteries used in portable electronic devices, hybrid vehicles, electric vehicles, and the like are often developed. Under these circumstances, lithium-containing olivine-type metal phosphates such as Li (Fe, Mn) PO ₄ are not greatly affected by resource constraints, and can exhibit high safety, resulting in high output. Therefore, it is an optimum positive electrode material for obtaining a large capacity lithium ion secondary battery. However, since these compounds are derived from a crystal structure and have low conductivity and low diffusibility of lithium ions, various developments have been made so far.

  For example, in Patent Document 1, an attempt is made to improve the performance of the obtained battery by making primary crystal particles ultrafine particles and shortening the lithium ion diffusion distance in the olivine-type positive electrode active material. In Patent Document 2, a conductive carbonaceous material is uniformly deposited on the particle surface of the positive electrode active material, and a regular electric field distribution is obtained on the particle surface to increase the output of the battery.

  On the other hand, when the particle surface of the positive electrode active material is coated with carbon, the amount of movement of lithium atoms between the inside and outside of the carbon film is limited, and conversely, it is difficult to improve the charge / discharge characteristics. Patent Document 3 discloses a method of coating carbon nanostructures such as carbon nanotubes and nanographene on the surface of positive electrode active material particles by plasma decomposition of an organic compound.

  On the other hand, as a technique for improving the physical properties of the battery by enhancing the binding property between the electrode active material and the conductive additive, Patent Document 4 contains these electrode active material, conductive additive, and cellulose fiber as an aqueous binder. An electrode slurry composition is disclosed, and this is applied onto an electrode current collector and dried to form an electrode active material layer.

Furthermore, since lithium is a rare valuable substance, sodium ion secondary batteries and the like are also attracting attention as alternatives to lithium ion secondary batteries.
For example, Patent Document 5 discloses a sodium secondary battery active material using marisite-type NaMnPO ₄ , and Patent Document 6 discloses a positive electrode active material containing sodium phosphate transition metal having an olivine structure. Substances are disclosed, and any literature shows that a high-performance sodium ion secondary battery can be obtained.

  By the way, since the charging reaction or discharging reaction of the battery is accompanied by heat generation, the temperature inside the secondary battery is inevitably higher than the temperature of the surrounding environment. When the secondary battery is repeatedly charged and discharged in such a high temperature environment, the volume of the active material particles changes due to the insertion and desorption of lithium accompanying the charge and discharge cycle, or the transition metal in the positive electrode active material to the electrolyte solution. It is also known that the deterioration of the cycle characteristics of the secondary battery accelerates due to the phenomenon that the elution of the battery becomes remarkable. Therefore, a secondary battery that exhibits excellent cycle characteristics even in a high temperature environment is desired, and various attempts are being made.

  For example, with respect to the latter phenomenon, Non-Patent Document 1 discloses that in lithium manganese phosphate doped with iron, manganese is easily eluted and is distributed in primary particles with a concentration gradient, whereby a manganese electrolyte is obtained. Is suppressed, and good cycle characteristics under high temperature environment are secured.

JP 2010-251302 A JP 2001-15111 A JP 2011-76931 A International Publication No. 2012/074040 JP 2008-260666 A JP 2011-34963 A

Liangtao Yang et al., Concentration-gradient LiMn0.8Fe0.2PO4cathode material for high performance lithium ion battery, Journal of Power Sources, 304, p.293-300 (2016)

  However, in the method described in Non-Patent Document 1, in order to create a concentration gradient in the manganese distribution in the lithium manganese phosphate oxide, the phosphorous manganese phosphate is once produced by a hydrothermal method, Manganese lithium oxide must be re-subjected to the hydrothermal method together with the raw materials for lithium iron phosphate, the manufacturing method is very complicated, and there is still room for improvement in cycle characteristics in a high-temperature environment. There is.

  Therefore, the subject of this invention is providing the polyanion positive electrode active material which can express the cycling characteristics outstanding also in high temperature environment, and its simple manufacturing method.

  Therefore, the present inventors have made various studies and as a result, the particle surface of the polyanion material (oxide) represented by a specific formula is densely filled with the interparticle voids of the packing structure formed by the polyanion positive electrode active material. In addition, a polyanion positive electrode active material in which carbon and a specific inorganic compound such as zinc oxide or aluminum oxide are supported can be used to obtain a secondary battery having excellent cycle characteristics at high temperatures, and a predetermined material. In the method for producing a polyanion positive electrode active material obtained by subjecting the mixed liquid added with hydrothermal reaction to a specific salt that generates a carbon source and a specific inorganic compound, such a polyanion positive electrode active material is obtained. It has also been found that it can be easily obtained, and the present invention has been completed.

That is, the present invention includes at least the following formula (A), (B) or (C) containing iron or manganese:
LiFe _a Mn _b M _c PO ₄ (A)
(In the formula (A), M represents Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd. A, b, and c are 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.2, and 2a + 2b + (M valence) × c = 2 and a number satisfying a + b ≠ 0 are shown.)
_{Li 2 Fe d Mn e N f} SiO 4 ··· (B)
(In the formula (B), N represents Ni, Co, Al, Zn, V, or Zr. D, e, and f are 0 ≦ d ≦ 1, 0 ≦ e ≦ 1, and 0 ≦ f <1, 2d + 2e +. (The valence of N) × f = 2 is satisfied, and d + e ≠ 0 is satisfied.)
NaFe _g Mn _h Q _i PO ₄ (C)
(In the formula (C), Q represents Mg, Ca, Co, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd. G, h, and i are 0 ≦ g ≦. 1, 0 ≦ h ≦ 1, 0 ≦ i <1, and 2g + 2h + (valence of Q) × i = 2 and a number satisfying g + h ≠ 0 are shown.)
A polyanionic positive electrode active material in which carbon and zinc oxide and / or aluminum oxide are supported on the particle surface of the polyanionic material represented by the formula (1) is provided.

Further, the present invention provides the following formula (A), (B) or (C) containing at least iron or manganese:
LiFe _a Mn _b M _c PO ₄ (A)
(In the formula (A), M represents Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd. A, b, and c are 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.2, and 2a + 2b + (M valence) × c = 2 and a number satisfying a + b ≠ 0 are shown.)
_{Li 2 Fe d Mn e N f} SiO 4 ··· (B)
(In the formula (B), N represents Ni, Co, Al, Zn, V, or Zr. D, e, and f are 0 ≦ d ≦ 1, 0 ≦ e ≦ 1, and 0 ≦ f <1, 2d + 2e +. (The valence of N) × f = 2 is satisfied, and d + e ≠ 0 is satisfied.)
NaFe _g Mn _h Q _i PO ₄ (C)
(In the formula (C), Q represents Mg, Ca, Co, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd. G, h, and i are 0 ≦ g ≦. 1, 0 ≦ h ≦ 1, 0 ≦ i <1, and 2g + 2h + (valence of Q) × i = 2 and a number satisfying g + h ≠ 0 are shown.)
A method of producing a polyanionic positive electrode active material in which carbon and zinc oxide and / or aluminum oxide are supported on the particle surface of the polyanion material represented by
Step (I) of obtaining complex X by mixing phosphoric acid compound or silicic acid compound with mixture X containing lithium compound or sodium compound,
Step (II) of obtaining the complex Y by subjecting the obtained complex X and slurry water Y containing a metal salt containing at least an iron compound or a manganese compound to a hydrothermal reaction, and the obtained complex Y Step of adding zinc salt and / or aluminum salt to produce zinc oxide and / or aluminum oxide and firing (III)
And providing a method for producing a polyanionic positive electrode active material, wherein step (I) or step (III) includes a step of adding a carbon source.

  According to the polyanion positive electrode active material of the present invention, carbon densely fills the interparticle voids of the packing structure formed by the polyanion material, and the carbon and the specific inorganic compound are supported on the particle surface of the polyanion material. Thus, despite being obtained by a simple method, excellent cycle characteristics can be exhibited in a high temperature environment.

Hereinafter, the present invention will be described in detail.
The polyanion material used for the polyanion positive electrode active material obtained in the present invention is represented by the following formula (A), (B) or (C):
LiFe _a Mn _b M _c PO ₄ (A)
(In the formula (A), M represents Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd. A, b, and c are 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.2, and 2a + 2b + (M valence) × c = 2 and a number satisfying a + b ≠ 0 are shown.)
_{Li 2 Fe d Mn e N f} SiO 4 ··· (B)
(In the formula (B), N represents Ni, Co, Al, Zn, V, or Zr. D, e, and f are 0 ≦ d ≦ 1, 0 ≦ e ≦ 1, 0 ≦ f <1, and 2d + 2e +. (The valence of N) × f = 2 is satisfied, and d + e ≠ 0 is satisfied.)
NaFe _g Mn _h Q _i PO ₄ (C)
(In the formula (C), Q represents Mg, Ca, Co, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd. G, h, and i are 0. ≦ g ≦ 1, 0 ≦ h ≦ 1, 0 ≦ i <1, and 2g + 2h + (Q valence) × i = 2 and a number satisfying g + h ≠ 0 are shown.
It is expressed by one of the following formulas.
All of these polyanion materials have an olivine structure and contain at least iron or manganese. The polyanion positive electrode active material composed of the polyanion material represented by the above formula (A) or formula (B) is a so-called positive electrode active material for a lithium ion secondary battery, and is composed of the polyanion material represented by the above formula (C). The polyanion positive electrode active material is a so-called positive electrode active material for sodium ion secondary batteries.

The polyanion material represented by the above formula (A) is an olivine-type transition metal lithium compound containing iron (Fe) and manganese (Mn) as at least transition metals. In the formula (A), M represents Mg, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and is preferably Mg, Zr, Mo, or Co. a is 0 ≦ a ≦ 1, preferably 0.01 ≦ a ≦ 0.99, and more preferably 0.1 ≦ a ≦ 0.9. b is 0 ≦ b ≦ 1, preferably 0.01 ≦ b ≦ 0.99, and more preferably 0.1 ≦ b ≦ 0.9. c is 0 ≦ c ≦ 0.2, and preferably 0 ≦ c ≦ 0.1. These b1 and c are numbers satisfying 2a + 2b + (M valence) × c = 2 and satisfying a + b ≠ 0. Specific examples of the polyanion material represented by the above formula (A) include LiFe _0.9 Mn _0.1 PO ₄ , LiFe _0.2 Mn _0.8 PO ₄ , LiFe _0.15 Mn _0.75 Mg _0.1 PO ₄ , LiFe _0.19 Mn _0.75 Zr _0.03 PO. _{4 and the} like, and LiFe _0.2 Mn _0.8 PO ₄ is particularly preferable.

The polyanion material represented by the above formula (B) is an olivine-type silicate transition metal lithium compound containing iron (Fe) and manganese (Mn) as at least transition metals. In the formula (B), N represents Ni, Co, Al, Zn, V, or Zr, and is preferably Co, Al, Zn, V, or Zr. d is 0 ≦ d ≦ 1, preferably 0 ≦ d <1, and more preferably 0.1 ≦ d ≦ 0.6. e is 0 ≦ d ≦ 1, preferably 0 ≦ e <1, and more preferably 0.1 ≦ e ≦ 0.6. f is 0 ≦ f <1, preferably 0 <f <1, and more preferably 0.05 ≦ f ≦ 0.4. These d, e, and f are numbers satisfying 2d + 2e + (N valence) × f = 2 and d + e ≠ 0. Specific examples of the polyanion material represented by the above formula (B) include Li ₂ Fe _0.45 Mn _0.45 Co _0.1 SiO ₄ , Li ₂ Fe _0.36 Mn _0.54 Al _0.066 SiO ₄ , Li ₂ Fe _0.45 Mn _0.45 Zn _{0.1 Examples thereof include} SiO ₄ , Li ₂ Fe _0.36 Mn _0.54 V _0.066 SiO ₄ , Li ₂ Fe _0.282 Mn _0.658 Zr _0.02 SiO ₄ , and among them, Li ₂ Fe _0.282 Mn _0.658 Zr _0.02 SiO ₄ is preferable.

The polyanion material represented by the above formula (C) is a so-called olivine-type transition metal sodium phosphate compound containing at least iron (Fe) and manganese (Mn) as transition metals. In the formula (C), Q represents Mg, Ca, Co, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and is preferably Mg, Zr, Mo, or Co. g is 0 ≦ g ≦ 1, and preferably 0 <g ≦ 1. h is 0 ≦ h ≦ 1, and preferably 0.5 ≦ h <1. i is 0 ≦ i <1, preferably 0 ≦ i ≦ 0.5, and more preferably 0 ≦ i ≦ 0.3. These g, h, and i are numbers satisfying 0 ≦ g ≦ 1, 0 ≦ h ≦ 1, and 0 ≦ i <1, 2 + g + 2h + (Q valence) × i = 2 and satisfying g + h ≠ 0. It is. Specific examples of the polyanion material represented by the above formula (C) include NaFe _0.9 Mn _0.1 PO ₄ , NaFe _0.2 Mn _0.8 PO ₄ , NaFe _0.15 Mn _0.7 Mg _0.15 PO ₄ , NaFe _0.19 Mn _0.75 Zr _0.03 PO. ₄ , NaFe _0.19 Mn _0.75 Mo _0.03 PO ₄ , NaFe _0.15 Mn _0.7 Co _0.15 PO _{4 and the} like, among which NaFe _0.2 Mn _0.8 PO ₄ is preferable.

  In the polyanionic positive electrode active material of the present invention, carbon and zinc oxide and / or aluminum oxide are supported on the particle surface of the polyanion material represented by the above formula (A), (B) or (C). . That is, on the particle surface of the polyanion material, one of these carbons or inorganic compounds is not present, and the other is effectively supported as a supplement to the portion where the particle surface of the polyanion material is exposed. Therefore, the carbon and the specific inorganic compound are combined to effectively support the particle surface of the polyanion material, while being firmly supported while embedding the entire particle surface of the polyanion material. When a polyanionic positive electrode active material is used as a positive electrode for a secondary battery, it effectively suppresses the elution of metals such as Fe and Mn into the electrolyte and the volume change of the active material particles during charging and discharging under high temperature environments. It is estimated that excellent cycle characteristics can be expressed in

Such carbon is carbon derived from a carbon source. Specific examples of the carbon source include cellulose nanofibers (abbreviation: CNF), water-insoluble conductive carbon materials other than cellulose nanofibers, and water-soluble materials. Carbon material.
Cellulose nanofiber is a skeletal component that occupies about 50% of all plant cell walls, and is a lightweight high-strength fiber that can be obtained by defibrating plant fibers constituting such cell walls to nano size, Carbon derived from cellulose nanofibers has a periodic structure. The fiber diameter of the cellulose nanofiber is 1 nm to 500 μm, and has good dispersibility in water. In addition, in the cellulose molecular chain constituting the cellulose nanofiber, since a periodic structure of carbon is formed, this is combined with the inorganic compound while being carbonized, and is firmly supported on the particle surface of the polyanion material. A useful positive electrode active material capable of improving cycle characteristics in a high temperature environment can be obtained.

  The water-insoluble conductive carbon material as the carbon source is a carbon source other than cellulose nanofibers, and the amount dissolved in 100 g of water at 25 ° C. is 0. 0 in terms of carbon atom equivalent of the water-insoluble conductive carbon material. It is a water-insoluble carbon material having a weight of less than 4 g, and itself is a carbon source having electrical conductivity without firing. Examples of the water-insoluble conductive carbon material include one or more selected from graphite, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black. Among these, graphite is preferable from the viewpoint of being effectively supported on the particle surface of the polyanion material in combination with a specific inorganic compound. The graphite may be any of artificial graphite (scaly, massive, earthy, graphene) or natural graphite.

The BET specific surface area of the water-insoluble conductive carbon material is preferably 1 to 750 m ² / g, more preferably 3 to 500 m ² / g, from the viewpoint of effectively enhancing cycle characteristics in a high temperature environment. Moreover, from the same viewpoint, the average particle size of the water-insoluble conductive carbon material is preferably 0.5 to 20 μm, more preferably 1.0 to 15 μm.

  Furthermore, the water-soluble carbon material as the carbon source means a carbon material that dissolves in 100 g of water at 25 ° C. in terms of carbon atom of the water-soluble carbon material, preferably 0.4 g or more, preferably 1.0 g or more, By being carbonized, it exists on the particle surface of the polyanion material as carbon. Examples of the water-soluble carbon material include one or more selected from saccharides, polyols, polyethers, and organic acids. More specifically, for example, monosaccharides such as glucose, fructose, galactose and mannose; disaccharides such as maltose, sucrose and cellobiose; polysaccharides such as starch and dextrin; ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol and butane Examples include polyols and polyethers such as diol, propanediol, polyvinyl alcohol, and glycerin; and organic acids such as citric acid, tartaric acid, and ascorbic acid. Among these, glucose, fructose, sucrose, and dextrin are preferable, and glucose is more preferable from the viewpoint of improving the solubility and dispersibility in a solvent and effectively functioning as a carbon material.

  Among these carbon sources, cellulose nanofibers are preferable from the viewpoint of effectively enhancing cycle characteristics in a high temperature environment in combination with the specific inorganic compound.

  The amount of carbon supported in the polyanionic positive electrode active material of the present invention corresponds to the carbon atom equivalent amount of these carbon sources, and the carbon source together with the inorganic compound described later is carbon ( As a carbon source-derived carbon), it coexists in the polyanionic positive electrode active material of the present invention. The amount of carbon supported (amount in terms of the amount of carbon derived from the carbon source) is preferably 0.3 to 10.0% by mass in the polyanionic positive electrode active material of the present invention, more preferably 0.5 to It is 8.0 mass%, More preferably, it is 0.7-5.0 mass%.

Specifically, when the carbon source is cellulose nanofiber, the amount of carbon derived from cellulose nanofiber in terms of atomic amount (carbon loading) is preferably 0.3 in the polyanionic positive electrode active material of the present invention. It is -8.0 mass%, More preferably, it is 0.5-5.0 mass%, More preferably, it is 0.7-4.0 mass%. In addition, when the carbon source is the above water-insoluble conductive carbon material, the atomic conversion amount (carbon loading amount) of carbon derived from the water-insoluble conductive carbon material is preferably in the polyanionic positive electrode active material of the present invention. Is 0.5-10.0 mass%, More preferably, it is 1.0-8.0 mass%, More preferably, it is 1.5-5.0 mass%. Furthermore, when the carbon source is the water-soluble carbon material, the amount of carbon derived from the water-soluble carbon material (amount of supported carbon) is preferably 0.5 in the polyanionic positive electrode active material of the present invention. It is -10.0 mass%, More preferably, it is 0.7-8.0 mass%, More preferably, it is 1.0-5.0 mass%.
In addition, the atomic conversion amount (carbon loading amount) of carbon derived from the carbon source present in the polyanionic positive electrode active material can be confirmed as the carbon amount measured using a carbon / sulfur analyzer.

  In the polyanionic positive electrode active material of the present invention, zinc oxide and aluminum oxide are supported on the particle surface of the polyanion material together with carbon. With carbon alone, it is difficult to sufficiently cover the particle surface of the polyanion material. By using these inorganic compounds, the inorganic compound is present on the portion where the carbon remaining on the particle surface of the polyanion material is not supported. It is presumed that the film is effectively supported while being thinned, and can exhibit excellent cycle characteristics in a high temperature environment without impairing conductivity.

  In order to support these zinc oxide and / or aluminum oxide on the particle surface of the polyanion material, a zinc salt and / or an aluminum salt that generates these zinc oxide and / or aluminum oxide is used. Such a zinc salt and / or aluminum salt may be any salt that produces zinc oxide and / or aluminum oxide through a firing step.

  Zinc salts that produce zinc oxide include zinc acetate, zinc chloride, zinc lactate, zinc succinate, zinc tartrate, zinc oxalate, zinc carbonate, zinc nitrate, zinc hydroxide, zinc alkoxide, and hydrates thereof. Is mentioned. Among these, zinc acetate and zinc chloride are preferable from the viewpoint of preventing unnecessary battery performance deterioration and availability.

  Examples of the aluminum salt that forms aluminum oxide include aluminum lactate, aluminum hydroxide, aluminum acetate, aluminum carbonate, aluminum gluconate, aluminum oxalate, aluminum nitrate, aluminum alkoxide, and hydrates thereof. Of these, aluminum lactate and aluminum hydroxide are preferable from the viewpoint of preventing unnecessary battery performance deterioration and availability.

  The amount of zinc oxide and aluminum oxide supported in the polyanionic positive electrode active material of the present invention is combined with carbon to effectively enhance cycle characteristics in a high temperature environment, and as much as possible to make zinc oxide and aluminum oxide as thin as possible. From the viewpoint of favorably maintaining a high battery capacity, it is preferably 0.01 to 3.0% by mass, more preferably 0.05 to 2.5% by mass in the polyanionic positive electrode active material of the present invention. Yes, more preferably 0.1 to 2.0% by mass. More specifically, the supported amount of zinc oxide is preferably 0.01 to 2.5% by mass, more preferably 0.05 to 2.0% by mass in the polyanionic positive electrode active material of the present invention. More preferably, it is 0.1-1.5 mass%. Further, the supported amount of aluminum oxide is preferably 0.05 to 3.0% by mass, more preferably 0.1 to 2.5% by mass in the polyanionic positive electrode active material of the present invention. Preferably it is 0.2-2.0 mass%.

The method for producing the polyanionic positive electrode active material of the present invention includes:
Step (I) of obtaining complex X by mixing phosphoric acid compound or silicic acid compound with mixture X containing lithium compound or sodium compound,
Step (II) of obtaining the complex Y by subjecting the obtained complex X and slurry water Y containing a metal salt containing at least an iron compound or a manganese compound to a hydrothermal reaction, and the obtained complex Y Step of adding zinc salt and / or aluminum salt to produce zinc oxide and / or aluminum oxide and firing (III)
And step (I) or step (III) includes a step of adding a carbon source.

Step (I) is a step of obtaining a composite X by mixing a phosphoric acid compound or a silicic acid compound with a mixture X containing a lithium compound or a sodium compound.
Examples of the lithium compound or sodium compound that can be used include hydroxides (for example, LiOH.H ₂ O, NaOH), carbonates, sulfates, and acetates. Of these, hydroxide is preferable.
The content of the lithium compound or silicate compound in the mixture X is preferably 5 to 50 parts by mass, more preferably 7 to 45 parts by mass with respect to 100 parts by mass of water. More specifically, when a phosphoric acid compound is used in step (I), the content of the lithium compound or sodium compound in the mixture X is preferably 5 to 50 parts by mass with respect to 100 parts by mass of water. Preferably it is 10-45 mass parts. Moreover, when a silicic acid compound is used, content of the silicic acid compound in the mixture X becomes like this. Preferably it is 5-40 mass parts with respect to 100 mass parts of water, More preferably, it is 7-35 mass parts.

  Here, for example, when using cellulose nanofiber as a carbon source, this process (I) includes the process of adding a cellulose nanofiber. In this case, specifically, cellulose nanofibers may be added to the mixture X containing a lithium compound or a sodium compound. The content of cellulose nanofibers in the mixture X is preferably 0.5 to 60 parts by mass, and more preferably 0.8 to 40 parts by mass with respect to 100 parts by mass of water in the mixture X, for example. More specifically, when a phosphoric acid compound is used in step (I), the content of cellulose nanofibers in the mixture X is preferably 0.5 to 20 parts by mass, more preferably 0.8 to 15 parts. Part by mass. Moreover, when a silicic acid compound is used, content of the cellulose nanofiber in the mixture X becomes like this. Preferably it is 0.5-60 mass parts, More preferably, it is 1-40 mass parts.

  Before mixing the phosphoric acid compound or the silicic acid compound with the mixture X, it is preferable to stir the mixture X in advance. The stirring time of the mixture X is preferably 1 to 15 minutes, more preferably 3 to 10 minutes. Moreover, the temperature of the mixture X becomes like this. Preferably it is 20-90 degreeC, More preferably, it is 20-70 degreeC.

Examples of the phosphoric acid compound used in the step (I) include orthophosphoric acid (H ₃ PO ₄ , phosphoric acid), metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, ammonium phosphate, and ammonium hydrogen phosphate. . Of these, phosphoric acid is preferably used, and is preferably used as an aqueous solution having a concentration of 70 to 90% by mass. In the step (I), when phosphoric acid is mixed with the mixture X, it is preferable to add phosphoric acid dropwise while stirring the mixture X. By adding phosphoric acid dropwise to the mixture X and adding it little by little, the reaction proceeds well in the mixture X, and the complex X is generated while being uniformly dispersed in the slurry. It can also be effectively suppressed.

The dropping rate of phosphoric acid into the mixture X is preferably 15 to 50 mL / min, more preferably 20 to 45 mL / min, and further preferably 28 to 40 mL / min. Moreover, the stirring time of the mixture X while dropping phosphoric acid is preferably 0.5 to 24 hours, and more preferably 3 to 12 hours. Furthermore, the stirring speed of the mixture X while dropping phosphoric acid is preferably 200 to 700 rpm, more preferably 250 to 600 rpm, and further preferably 300 to 500 rpm.
In addition, when stirring the mixture X, it is preferable to further cool below the boiling point temperature of the mixture X. Specifically, cooling to 80 ° C. or lower is preferable, and cooling to 20 to 60 ° C. is more preferable.

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

It is preferable that the mixture X after mixing a phosphoric acid compound or a silicic acid compound contains 2.0-4.0 mol of lithium or sodium with respect to 1 mol of phosphoric acid or silicic acid, and is 2.0-3. It is more preferable to contain 1 mol, and the lithium compound or sodium compound and the phosphoric acid compound or silicic acid compound may be used so as to obtain such an amount. More specifically, when a phosphoric acid compound is used in step (I), the mixture X after mixing the phosphoric acid compound is 2.7 to 3.3 mol of lithium or sodium with respect to 1 mol of phosphoric acid. It is preferable to contain 2.8-3.1 mol, and when a silicate compound is used in step (I), the mixture X after mixing the silicate compound is 1 mol of silicate. On the other hand, it is preferable to contain 2.0-4.0 mol of lithium, and it is more preferable to contain 2.0-3.0 mol of lithium.
What is necessary is just to use the said lithium compound or sodium compound, and a phosphoric acid compound or a silicic acid compound so that it may become such quantity.

By purging nitrogen to the mixture X after mixing the phosphate compound or the silicate compound, the reaction in the mixture is completed, and the polyanion material represented by the above (A) to (C) The precursor complex X is formed in the mixture. When nitrogen is purged, the reaction can proceed while the dissolved oxygen concentration in the mixture X is reduced, and the dissolved oxygen concentration in the resulting mixture containing the complex X is also effectively reduced. Therefore, oxidation of the iron compound or manganese compound added in the next step can be suppressed. In the mixture containing the complex X, the precursor of the polyanion material represented by the above (A) to (C) exists as fine dispersed particles. Such a complex X is, for example, a polyanion material represented by the above formula (A), and when a mixture X to which cellulose nanofibers are added as a carbon source is used, trilithium phosphate (Li ₃ PO ₄ ) and cellulose Obtained as a nanofiber composite.

The pressure for purging nitrogen is preferably 0.1 to 0.2 MPa, more preferably 0.1 to 0.15 MPa. Moreover, the temperature of the mixture X after mixing a phosphoric acid compound or a silicic acid compound becomes like this. Preferably it is 20-80 degreeC, More preferably, it is 20-60 degreeC. For example, in the case of the polyanion material represented by the above formula (A), the reaction time is preferably 5 to 60 minutes, more preferably 15 to 45 minutes.
Moreover, when purging nitrogen, it is preferable to stir the mixture X after mixing a phosphoric acid compound or a silicic acid compound from a viewpoint of making reaction progress favorable. The stirring speed at this time is preferably 200 to 700 rpm, more preferably 250 to 600 rpm.

  Further, from the viewpoint of more effectively suppressing the oxidation on the surface of the dispersed particles of the complex X and miniaturizing the dispersed particles, the dissolved oxygen concentration in the mixture X after mixing the phosphoric acid compound or the silicate compound is reduced to 0. 0.5 mg / L or less is preferable, and 0.2 mg / L or less is more preferable.

  In the step (II), the composite X obtained in the step (I) and the slurry water Y containing a metal salt containing at least an iron compound or a manganese compound are subjected to a hydrothermal reaction to obtain the composite Y. It is. The complex X obtained by the step (I) is used as a precursor of the polyanion material represented by the above (A) to (C) as a mixture, and contains at least an iron compound or a manganese compound. Is preferably used as slurry water Y. Thereby, while simplifying the process, the polyanion material represented by the above (A) to (C) becomes extremely fine particles and can efficiently carry zinc oxide or aluminum oxide in the subsequent process. Thus, a very useful positive electrode active material for a secondary battery can be obtained.

  Examples of iron compounds that can be used include iron acetate, iron nitrate, and iron sulfate. These may be used alone or in combination of two or more. Among these, iron sulfate is preferable from the viewpoint of improving battery characteristics.

  Examples of manganese compounds that can be used include manganese acetate, manganese nitrate, and manganese sulfate. These may be used alone or in combination of two or more. Among these, manganese sulfate is preferable from the viewpoint of improving battery characteristics.

When both an iron compound and a manganese compound are used as the metal salt, the use molar ratio of these manganese compound and iron compound (manganese compound: iron compound) is preferably 99: 1 to 1:99, more preferably 90. : 10 to 10:90. Moreover, the total addition amount of these iron compounds and manganese compounds is preferably 0.99 to 1.01 mol, more preferably 0.995 with respect to 1 mol of Li ₃ PO ₄ contained in the slurry water Y. ~ 1.005 mol.

Furthermore, you may use metal (M, N, or Q) salts other than an iron compound and a manganese compound as a metal salt as needed. M, N, and Q in the metal (M, N, or Q) salt have the same meanings as M, N, and Q in the above formulas (A) to (C), and as the metal salt, sulfate, halogen compound, organic Acid salts and hydrates thereof can be used. These may be used alone or in combination of two or more. Among them, it is more preferable to use a sulfate from the viewpoint of improving battery physical properties.
When these metal (M, N, or Q) salts are used, the total amount of iron compound, manganese compound, and metal (M, N, or Q) salt added is phosphoric acid in the mixture obtained in the above step (I). Or it is preferably 0.99 to 1.01 mole, and more preferably 0.995 to 1.005 mole relative to 1 mole of silicic acid.

  The amount of water used for the hydrothermal reaction is phosphoric acid or silicate ions contained in the slurry water Y from the viewpoint of the solubility of the metal salt used, the ease of stirring, the efficiency of synthesis, etc. Preferably it is 10-50 mol with respect to 1 mol, More preferably, it is 12.5-45 mol. More specifically, the amount of water used for the hydrothermal reaction is preferably 10 to 30 mol, more preferably 12 when the ions contained in the slurry water Y are phosphate ions. .5 to 25 moles. Moreover, when the ion contained in the slurry water Y is a silicate ion, Preferably it is 10-50 mol, More preferably, it is 12.5-45 mol.

In step (II), the order of addition of the iron compound, manganese compound and metal (M, N or Q) salt is not particularly limited. Moreover, while adding these metal salts, you may add antioxidant as needed. As such an antioxidant, sodium sulfite (Na ₂ SO ₃ ), sodium hydrosulfite (Na ₂ S ₂ O ₄ ), aqueous ammonia and the like can be used. From the viewpoint of preventing the generation of the polyanion material represented by the above formulas (A) to (C) from being suppressed by adding an excessive amount of the antioxidant, an iron compound, a manganese compound, and Preferably it is 0.01-1 mol with respect to the total of 1 mol of metal (M, N, or Q) salt used as needed, More preferably, it is 0.03-0.5 mol.

  The content of the complex Y in the slurry Y obtained by adding an iron compound, a manganese compound, and a metal (M, N or Q) salt or an antioxidant used as necessary is preferably 10 to 50% by mass. More preferably, it is 15-45 mass%, More preferably, it is 20-40 mass%.

The hydrothermal reaction in process (II) should just be 100 degreeC or more, and 130-180 degreeC is preferable. The hydrothermal reaction is preferably carried out in a pressure vessel, and when the reaction is carried out at 130 to 180 ° C, the pressure at this time is preferably 0.3 to 0.9 MPa, and the reaction is carried out at 140 to 160 ° C. The pressure is preferably 0.3 to 0.6 MPa. The hydrothermal reaction time is preferably 0.1 to 48 hours, more preferably 0.2 to 24 hours.
The obtained complex Y includes the polyanion material represented by the above formulas (A) to (C), and when cellulose nanofibers are used as a carbon source in the step (I), the cellulose nanofibers are used. Is also a complex. This can be isolated by washing with water after filtration and drying. As the drying means, freeze drying or vacuum drying is used.

The BET specific surface area of the obtained composite Y is preferably 5 to 40 m ² / g, more preferably 5 to 20 m from the viewpoint of improving cycle characteristics under a high temperature environment and maintaining a good battery capacity. ² / g.

  In the step (III), a zinc salt and / or an aluminum salt that generates zinc oxide and / or aluminum oxide is added to the composite Y obtained in the step (II) and fired. Thereby, while effectively suppressing the exposure of the particle surface of the polyanion material represented by the above (A) to (C), the carbon salt derived from the carbon source and the zinc salt are fired on the particle surface. And / or zinc oxide and / or aluminum oxide produced from the aluminum salt can be firmly supported together.

  As described above, the amount of zinc salt and / or aluminum salt added is such that the supported amount of zinc oxide and / or aluminum oxide in the resulting polyanionic positive electrode active material is within the above range in total. Well, for example, from the viewpoint of effectively carrying these on the particle surface of the polyanion material free from carbon derived from the carbon source while making the layer as thin as possible, it is preferably 0.03-9. It is 0 mass part, More preferably, it is 0.15-7.5 mass part, More preferably, it is 0.3-6.0 mass part.

  The step (III) can include a step of adding a carbon source. However, when the step (I) includes a step of adding a carbon source, the step of adding a carbon source may not be included here. . That is, the method for producing a polyanionic positive electrode active material of the present invention includes a step of adding a carbon source in either step (I) or step (III), or a carbon source is added in both steps. It is a manufacturing method including a process. In the step (III), when such a carbon source is added, it is preferably added to the obtained composite Y together with the zinc salt and the aluminum salt.

When a water-insoluble conductive carbon material is added as a carbon source, it is preferable to dry-mix with the zinc salt and aluminum salt after the addition and before firing. The dry mixing is preferably mixing by a normal ball mill, and more preferably by a planetary ball mill capable of revolving. In addition, the water-insoluble conductive carbon material is densely and uniformly dispersed on the particle surface of the polyanion material represented by the above formulas (A) to (C), and is effectively compressed as carbonized carbon. More preferably, the composite Y is mixed to give a composite Y ′ while applying a force and a shearing force. The process of mixing while applying a compressive force and a shearing force is preferably performed in a closed container equipped with an impeller. The peripheral speed of the impeller is preferably 25 to 40 m / s, more preferably 27 from the viewpoint of increasing the tap density of the obtained positive electrode active material and effectively reducing the amount of adsorbed moisture by reducing the BET specific surface area. ~ 40 m / s. The mixing time is preferably 5 to 90 minutes, more preferably 10 to 80 minutes.
The peripheral speed of the impeller means the speed of the outermost end of the rotary stirring blade (impeller), which can be expressed by the following formula (1), and is mixed while applying compressive force and shearing force. The processing time may vary depending on the peripheral speed of the impeller so that it becomes longer as the peripheral speed of the impeller is slower.
Impeller peripheral speed (m / s) =
Impeller radius (m) × 2 × π × rotational speed (rpm) ÷ 60 (1)

In step (III), the processing time and / or the impeller peripheral speed when performing the mixing process while applying the compressive force and the shearing force need to be adjusted as appropriate according to the amount of the composite Y charged into the container. There is. And by operating a container, it becomes possible to perform the process which mixes this, adding compression force and shear force to these mixtures between an impeller and a container inner wall, and said Formula (A)-(C A polyanionic positive electrode active material that disperses a water-insoluble conductive carbon material densely and uniformly on the surface of the polyanionic material represented by the formula (II) and exhibits high cycle characteristics even in a high temperature environment in combination with zinc oxide and aluminum oxide. Can be obtained.
For example, when the mixing process is performed for 6 to 90 minutes in an airtight container equipped with an impeller rotating at a peripheral speed of 25 to 40 m / s, the amount of the complex Y to be charged into the container is an effective container (airtight equipped with an impeller). Of the containers, a container corresponding to a part capable of accommodating the complex Y) per cm ³ is preferably 0.1 to 0.7 g, more preferably 0.15 to 0.4 g.

Examples of the apparatus equipped with a closed container that can easily perform mixing while applying compressive force and shear force include a high-speed shear mill, a blade-type kneader, and the like. Fine particle composite apparatus Nobilta (manufactured by Hosokawa Micron Corporation) can be suitably used.
As the processing conditions for the mixing, the processing temperature is preferably 5 to 80 ° C, more preferably 10 to 50 ° C. The treatment atmosphere is not particularly limited, but is preferably an inert gas atmosphere or a reducing gas atmosphere.

  When a water-soluble carbon material or cellulose nanofiber is added as a carbon source, it is preferable to perform wet mixing after the addition and before firing. In this case, it is preferable to add water from the viewpoint of dispersing these carbon sources together with zinc oxide and aluminum oxide and effectively supporting them on the particle surface of the polyanion material. The amount of water added is preferably 20 to 500 parts by mass, more preferably 30 to 400 parts by mass, and still more preferably 40 to 300 parts by mass with respect to 100 parts by mass of the composite Y.

  The wet mixing means is not particularly limited and can be performed by a conventional method. The temperature at the time of mixing after adding a water-soluble carbon material to the composite Y is preferably 5 to 80 ° C, more preferably 7 to 70 ° C. The resulting mixture is preferably dried before firing. Examples of the drying means include spray drying, vacuum drying, freeze drying and the like, and spray drying is particularly preferable.

  In the step (III), the obtained mixture is fired. Firing is preferably performed in a reducing atmosphere or an inert atmosphere. The firing temperature is preferably 500 to 800 ° C, more preferably 600 to 770 ° C, from the viewpoint of carbonizing the carbon source more effectively and from the viewpoint of effectively generating zinc oxide or aluminum oxide from the zinc salt or aluminum salt. More preferably, it is 650-750 degreeC. The firing time is preferably 10 minutes to 3 hours, more preferably 30 minutes to 1.5 hours.

The tap density of the polyanionic positive electrode active material of the present invention is preferably 0.5 to 1.6 g / cm ³ , more preferably 0.8 to 1.6 g from the viewpoint of improving cycle characteristics in a high temperature environment. / Cm ³ .

Furthermore, the BET specific surface area of the polyanionic positive electrode active material of the present invention is preferably 5 to 40 m ² / g, more preferably 7 to 30 m ² / g, from the viewpoint of improving cycle characteristics in a high temperature environment. .

  As a secondary battery that is a lithium ion secondary battery or a sodium ion secondary battery to which the positive electrode for a secondary battery containing the polyanionic positive electrode active material of the present invention can be applied, a positive electrode, a negative electrode, an electrolyte, and a separator are essential components. If it does, it will not specifically limit.

  Here, as for the negative electrode, as long as lithium ions or sodium ions can be occluded at the time of charging and can be released at the time of discharging, the material configuration is not particularly limited, and those having a known material configuration can be used. . For example, a carbon material such as lithium metal, sodium metal, graphite, or amorphous carbon. It is preferable to use an electrode formed of an intercalating material capable of electrochemically inserting and extracting lithium ions or sodium ions, particularly a carbon material.

  The electrolytic solution is obtained by dissolving a supporting salt in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is usually used for an electrolyte solution of a lithium ion secondary battery or a sodium ion secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones Nitriles, lactones, oxolane compounds and the like can be used.

The type of the supporting salt is not particularly limited, but in the case of a lithium ion secondary battery, an inorganic salt selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , a derivative of the inorganic salt, LiSO ₃ CF ₃ , an organic material selected from LiC (SO ₃ CF ₃ ) ₂ and LiN (SO ₃ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ) It is preferably at least one of a salt and a derivative of the organic salt. In the case of a sodium ion secondary battery, an inorganic salt selected from NaPF ₆ , NaBF ₄ , NaClO ₄ and NaAsF ₆ , a derivative of the inorganic salt, NaSO ₃ CF ₃ , NaC (SO ₃ CF ₃ ) ₂ and NaN (SO ₃ CF ₃ ) ₂ , NaN (SO ₂ C ₂ F ₅ ) ₂ and NaN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), and at least one of derivatives of the organic salt It is preferable.

  The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a polyolefin polymer (polyethylene, polypropylene) porous film may be used.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

[Example 1]
12.72 g of LiOH.H ₂ O, 90 mL of water, and 6.8 g of cellulose nanofiber (Cerish KY-100G, manufactured by Daicel Finechem, fiber diameter 4 to 100 nm) were mixed to obtain slurry water. Next, 11.53 g of 85% aqueous phosphoric acid solution was added dropwise at 35 mL / min while stirring the resulting slurry water at a temperature of 25 ° C. for 5 minutes, followed by 12 hours under a nitrogen gas purge at 400 rpm. By stirring at a speed, a mixture X containing the complex X (slurry water X ¹ , dissolved oxygen concentration 0.5 mg / L) was obtained.
Such slurry water ^{X 1,} compared per mole of phosphorus and contained lithium 2.97 mol.

Next, 5.56 g of FeSO ₄ · 7H ₂ O and 19.29 g of MnSO ₄ · 5H ₂ O were added to 121.0 g of the obtained slurry water X ¹ and mixed to obtain slurry water Y ¹ . Then, the slurry water Y ¹ obtained was charged into an autoclave and subjected to 1 hour hydrothermal reaction at 170 ° C.. The pressure in the autoclave was 0.8 MPa. The produced crystal was filtered, and then washed with 12 parts by mass of water with respect to 1 part by mass of the crystal. The washed crystal was freeze-dried at −50 ° C. for 12 hours to give a composite Y ¹ (chemical composition of oxide represented by formula (A): LiMn _0.8 Fe _0.2 PO ₄ , BET specific surface area 21 m ² / g, average grain 60 nm in diameter) was obtained.
The resultant composite Y ^{1 (} 5.0 g) and zinc acetate dihydrate (manufactured by Nippon Chemical Industry Co., Ltd., purity: 98%) are mixed with 0.068 g to be provided in a planetary ball mill (P-5, manufactured by Fritsch). A solvent obtained by mixing 90 g of ethanol and 10 g of water was added thereto. Next, 100 g of a ball (ball diameter: 1 mm) was used and mixed for 1 hour at a rotation speed of 400 rpm. The obtained mixture was filtered, the solvent was distilled off using an evaporator, and then calcined at 700 ° C. for 1 hour in a reducing atmosphere to obtain a positive electrode active material for lithium ion secondary batteries (LiFe _0.2 Mn _0.8 PO ₄ , carbon Source: CNF, carbon loading = 2.0 mass%, ZnO loading = 0.5 mass%).

[Example 2]
Except for the addition amount of zinc acetate dihydrate being 0.136 g, in the same manner as in Example 1, lithium manganese iron phosphate (LiFe _0.2 Mn _0.8 PO ₄ , carbon source: CNF, supported amount of carbon = 2. 0% by mass, ZnO loading = 1.0% by mass).

[Example 3]
Except for using 0.287 g of aluminum lactate (Taxelum M-160L, manufactured by Taki Chemical Co., Ltd., Al ₂ O ₃ content 8.7% by mass) instead of zinc acetate dihydrate, the same procedure as in Example 1 was performed. Lithium manganese iron phosphate (LiFe _0.2 Mn _0.8 PO ₄ , carbon source: CNF, carbon loading = 2.0 mass%, Al ₂ O ₃ loading = 0.5 mass%) was obtained.

[Example 4]
Except that 0.575 g of aluminum lactate was used in place of zinc acetate dihydrate, lithium iron manganese phosphate (LiFe _0.2 Mn _0.8 PO ₄ , carbon source: CNF, carbon loading = 2.0% by mass and the amount of Al ₂ O ₃ supported = 1.0% by mass).

[Example 5]
In the same manner as in Example 1, except that cellulose nanofibers were not added before hydrothermal synthesis and 0.2 g of glucose was used simultaneously with zinc acetate dihydrate, lithium manganese iron phosphate (LiFe _0.2 Mn _0.8 PO ₄ , Carbon source: glucose, carbon loading = 4.0% by mass, ZnO = 1.0% by mass).

[Example 6]
A slurry water was obtained by mixing 5.60 g (140 mmol) of NaOH, 90 g of water, and 3.4 g of cellulose nanofiber. Then, the resulting slurry water was stirred at the stirring rate 400rpm while maintaining the 40 ° C., to obtain a mixed solution ^{X 2} by mixing 85% aqueous solution of phosphoric acid 5.77 g (50 mmol) here. Next, with respect to mixture ^{X 2} obtained, to obtain a mixture solution ^{X 2} containing nitrogen to purge the (0.2 MPa) is adjusted to the concentration of dissolved oxygen 0.5 mg / L precursor. To this mixture ^{X 2} give the FeSO ₄ · _7H 2 O 2.78g and MnSO ₄ · _5H 2 O 9.65g was added to mixture ^{X 2.} Here, in mixture ^{X 2,} with respect to phosphorus 1 mol, Na was 2.8 moles.
Then, the mixture X ² is added to the autoclave, the autoclave was purged with nitrogen, followed by 3 hours hydrothermal reaction at 200 ° C.. After carrying out the hydrothermal reaction, the mixture is allowed to cool, and the produced crystals are filtered, then washed with water, freeze-dried for about 12 hours, and the complex Y ¹ (of the oxide represented by formula (C)) is obtained. Chemical composition: NaFe _0.2 Mn _0.8 PO ₄ , BET specific surface area 16 m ² / g, average particle size 100 nm). 5 g of the obtained complex Y ¹ and 0.068 g of zinc acetate dihydrate (corresponding to 0.5% by mass in terms of the amount of zinc oxide supported in the positive electrode active material for sodium ion secondary battery) were mixed. It put into the container with which the planetary ball mill was equipped, and the solvent obtained by mixing ethanol 90g and water 10g was added to this. Next, 100 g of a ball (ball diameter: 1 mm) was used and mixed for 1 hour at a rotation speed of 400 rpm. The obtained mixture was filtered, the solvent was distilled off using an evaporator, and then calcined at 700 ° C. for 1 hour in a reducing atmosphere to obtain a positive electrode active material for sodium ion batteries (NaFe _0.2 Mn _0.8 PO ₄ , carbon source: CNF, carbon loading = 2.0 mass%, ZnO loading = 0.5 mass%).

[Example 7]
Except for the addition amount of zinc acetate dihydrate being 0.136 g, in the same manner as in Example 6, sodium manganese iron phosphate (NaFe _0.2 Mn _0.8 PO ₄ , carbon source: CNF, supported amount of carbon = 2. 0% by mass, ZnO loading = 1.0% by mass).

[Example 8]
Sodium manganese phosphate (NaFe _0.2 Mn _0.8 PO ₄ , carbon source: CNF, carbon loading amount = same as in Example 6 except that 0.287 g of aluminum lactate was used instead of zinc acetate dihydrate 2.0% by mass and the amount of Al ₂ O ₃ supported = 0.5% by mass).

[Example 9]
Sodium manganese phosphate (NaFe _0.2 Mn _0.8 PO ₄ , carbon source: CNF, carbon loading amount = same as in Example 6 except that 0.575 g of aluminum lactate was used instead of zinc acetate dihydrate 2.0% by mass and the amount of Al ₂ O ₃ supported = 1.0% by mass).

[Example 10]
Cellulose manganese iron (NaFe _0.2 Mn _0.8 PO ₄ , NaFe _0.2 Mn _0.8 PO ₄₎ was added in the same manner as in Example 6 except that cellulose nanofibers were not added before hydrothermal synthesis and 0.2 g of glucose was used simultaneously with zinc acetate dihydrate. Carbon source: glucose, carbon loading = 4.0% by mass, ZnO loading = 1.0% by mass).

[Comparative Example 1]
Except that zinc acetate dihydrate was not added, lithium iron manganese phosphate (LiFe _0.2 Mn _0.8 PO ₄ , carbon source: glucose, supported amount of carbon = 4.0% by mass) in the same manner as in Example 5. Got.

[Comparative Example 2]
Except that zinc acetate dihydrate was not added, sodium iron manganese phosphate (NaFe _0.2 Mn _0.8 PO ₄ , carbon source: glucose, supported amount of carbon = 4.0% by mass) in the same manner as in Example 10. Got.

<< Evaluation of cycle characteristics under high temperature environment >>
Using the positive electrode active materials obtained in Examples 1 to 10 and Comparative Examples 1 and 2, positive electrodes of lithium ion secondary batteries or sodium ion secondary batteries were produced. Specifically, the obtained positive electrode active material, ketjen black and polyvinylidene fluoride were mixed at a mass ratio of 75: 20: 5, and N-methyl-2-pyrrolidone was added thereto and kneaded sufficiently. A positive electrode slurry was prepared. The positive electrode slurry was applied to a current collector made of an aluminum foil having a thickness of 20 μm using a coating machine, and vacuum dried at 80 ° C. for 12 hours.
Thereafter, it was punched into a disk shape of φ14 mm and pressed at 16 MPa for 2 minutes using a hand press to obtain a positive electrode.
Next, a coin-type secondary battery was constructed using the positive electrode. A lithium foil (in the case of a lithium ion secondary battery) or a sodium foil (in the case of a sodium ion secondary battery) punched to φ15 mm was used as the negative electrode. In the electrolyte solution, LiPF ₆ (in the case of a lithium ion secondary battery) or NaPF ₆ (in the case of a sodium ion secondary battery) is mixed in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate are mixed at a volume ratio of 1: 1. Those dissolved at a concentration of 1 mol / L were used. As the separator, a known one such as a polymer porous film such as polypropylene was used. These battery components were assembled and housed in a conventional manner in an atmosphere with a dew point of −50 ° C. or lower to produce a coin-type secondary battery (CR-2032).

A charge / discharge test was performed using the manufactured secondary battery. In the case of a lithium ion battery, the charging condition is a constant current and constant voltage charge with a current of 1 CA (170 mA / g) and a voltage of 4.5 V, the discharge condition is 1 CA (170 mA / g) and a constant current discharge with a final voltage of 2.0 V. As a result, the discharge capacity at 1 CA was obtained. In the case of a sodium ion battery, the charging conditions are a constant current and constant voltage charging with a current of 1 CA (154 mA / g) and a voltage of 4.5 V, the discharging conditions are a constant current discharge of 1 CA (154 mA / g) and a final voltage of 2.0 V. As a result, the discharge capacity at 1 CA was obtained. Furthermore, 100 cycles were repeatedly tested under the same charge / discharge conditions, and the capacity retention rate (%) was determined by the following formula (1). All charge / discharge tests were conducted at 45 ° C.
Capacity retention (%) = (discharge capacity after 100 cycles) / (discharge capacity after 1 cycle)
× 100 (1)
The results are shown in Tables 1 and 2.

  From the above results, it can be seen that the positive electrode active material of the example can exhibit excellent cycle characteristics in a high temperature environment in the obtained battery as compared with the positive electrode active material of the comparative example.

Claims (4)

On the particle surface of the polyanion material represented by LiFe _0.2 Mn _0.8 PO ₄ or NaFe _0.2 Mn _0.8 PO ₄ , carbon derived from cellulose nanofibers having an atomic conversion amount of 0.3 to 10 % by mass , 0.5 to 1 polyanion-based positive active material .0 oxide zinc is supported amount of mass% is carrying. On the particle surface of the polyanion material represented by LiFe _0.2 Mn _0.8 PO ₄ or NaFe _0.2 Mn _0.8 PO ₄ , carbon derived from cellulose nanofibers having an atomic conversion amount of 0.3 to 10 % by mass , 0.5 to 1 2.0 is a supported amount of weight percent oxide zinc is a method for producing a polyanion-based positive active material obtained by carrying,
The mixture X containing a lithium compound or sodium compound, a mixture of phosphoric acid compound to obtain a complex X step (I),
A complex X obtained, step a slurry water Y containing iron compound and manganese compound is obtained a composite Y subjected to hydrothermal reaction (II), and the obtained complex Y100 parts by weight Step of adding zinc salt for producing zinc oxide at 0.03 to 9.0 parts by mass and baking (III)
And a method of producing a polyanionic positive electrode active material, wherein the step (I) or the step (III) includes a step of adding cellulose nanofibers. The manufacturing method of the polyanion type positive electrode active material of Claim 2 with which the process (I) and process (III) include the process of adding a cellulose nanofiber. The method for producing a polyanionic positive electrode active material according to claim 2 or 3 , wherein step (III) includes a spray drying step.