JP7099286B2 - Lithium Nickel Cobalt Molybdenum Oxide - Google Patents

Description

The present invention relates to a lithium nickel cobalt molybdenum oxide used as a positive electrode active material for a lithium ion secondary battery.

It is known that various materials are used as the positive electrode active material of the lithium ion secondary battery. Among them, the lithium nickel oxide represented by LiNiO ₂ was widely used as a positive electrode active material at the beginning of the development of the lithium ion secondary battery as described in Patent Document 1.

In addition, a lithium nickel metal oxide in which a part of nickel in LiNiO ₂ is replaced with another metal has been developed, and research on a lithium ion secondary battery using the lithium nickel metal oxide as a positive electrode active material has been energetically studied. It has been done. In particular, in recent years, many lithium ion secondary batteries have been reported in which lithium nickel cobalt aluminum oxide having a layered rock salt structure in which a part of nickel of LiNiO ₂ is replaced with cobalt and aluminum is used as a positive electrode active material.

Patent Document 2 specifically describes a lithium ion secondary battery using LiNi _0.81 Co _0.15 Al _0.04 O ₂ as a positive electrode active material.

In Patent Document 3, Lithium ion using LiNi _0.8 Co _0.16 Al _0.04 O ₂ or LiNi _0.8 Co _0.15 Al _0.04 O _1.9 F _0.1 as the positive electrode active material is adopted. The secondary battery is specifically described.

Patent Document 4 specifically describes a lithium ion secondary battery using LiNi _0.8 Co _0.15 Al _0.05 O ₂ as a positive electrode active material.

Patent Document 5 describes Li _1.013 Ni _0.831 Co _0.119 Al _0.050 O ₂ , Li _1.013 Ni _0.858 Co _0.123 Al _0.020 O ₂ or Li ₁ as the positive electrode active material. _.013 A lithium ion secondary battery using Ni _0.867 Co _0.098 Al _0.035 O ₂ is specifically described.

Japanese Unexamined Patent Publication No. 63-12126 Japanese Unexamined Patent Publication No. 2006-128119 Japanese Unexamined Patent Publication No. 2006-278341 Japanese Unexamined Patent Publication No. 2014-139926 JP-A-2017-195020

However, the demand for the positive electrode active material of the lithium ion secondary battery is increasing, and the provision of a new lithium composite metal oxide that can be a better positive electrode active material is eagerly desired.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a new material that can be a positive electrode active material.

As a result of diligent studies by the present inventor, it has been found that lithium nickel cobalt tungsten oxide in which a part of nickel of LiNiO ₂ is replaced with cobalt and tungsten is a suitable positive electrode active material. Furthermore, it was found that lithium nickel cobalt molybdenum oxide in which a part of nickel in LiNiO ₂ is replaced with cobalt and molybdenum is a positive electrode active material that is as good as or better than lithium nickel cobalt tungsten oxide.
The present invention has been completed based on such findings.

The lithium nickel cobalt molybdenum oxide of the present invention is characterized by being represented by the following general formula (1).
General formula (1) Li _a Ni _b Co _{c Mod De Of F g}
In the general formula (1), a, b, c, d, e, f, g are 0.5 ≦ a ≦ 2, 0.5 ≦ b ≦ 0.97, 0 <c <0.5, 0 <. It satisfies d <0.5, 0 ≦ e ≦ 0.2, b + c + d + e = 1, 1.8 ≦ f ≦ 2.2, and 0 ≦ g ≦ 0.2. D is a dope element.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a new material that can be a suitable positive electrode active material.

6 is a cross-sectional SEM image of secondary particles in the lithium nickel cobalt molybdenum oxide of Example 1.

Hereinafter, the best mode for carrying out the present invention will be described. Unless otherwise specified, the numerical range "x to y" described in the present specification includes the lower limit x and the upper limit y. Then, a numerical range can be configured by arbitrarily combining these upper limit values and lower limit values, as well as the numerical values listed in the examples. Further, the numerical value arbitrarily selected from the numerical range can be set as the upper limit and the lower limit.

The lithium nickel cobalt molybdenum oxide of the present invention (hereinafter, may be abbreviated as NCMo oxide of the present invention, and the lithium nickel cobalt molybdenum oxide may be abbreviated as NCMo oxide) is generally described below. It is characterized by being represented by the equation (1).
General formula (1) Li _a Ni _b Co _{c Mod De Of F g}
In the general formula (1), a, b, c, d, e, f, g are 0.5 ≦ a ≦ 2, 0.5 ≦ b ≦ 0.97, 0 <c <0.5, 0 <. It satisfies d <0.5, 0 ≦ e ≦ 0.2, b + c + d + e = 1, 1.8 ≦ f ≦ 2.2, and 0 ≦ g ≦ 0.2. D is a dope element.

The NCMo oxide of the present invention functions as a positive electrode active material of a lithium ion secondary battery. The NCMo oxide of the present invention preferably has a layered rock salt structure.

Since the valence of lithium is +1 and the valence of oxygen is -2, in the conventional lithium nickel-nickel cobalt aluminum oxide, lithium was removed in order to ensure the electrical neutrality of the metal and oxygen. The total valence of nickel-cobalt-aluminum is +3. Here, since cobalt and aluminum are stable at a valence of +3, it is considered that the valence of nickel is also +3. In the lithium nickel cobalt aluminum oxide, the element that preferentially contributes to the oxidation reaction during charging is nickel.
Then, as an oxidation reaction at the time of charging in the lithium nickel cobalt aluminum oxide, one-electron oxidation with Ni ³⁺ → Ni ⁴⁺ + e ⁻ occurs.

Molybdenum is present in the NCMo oxide of the present invention. Molybdenum has a valence of +6 and is stable. Due to the presence of molybdenum with a high oxidation number, it can be said that the NCMo oxide of the present invention allows the presence of nickel having a valence of +2 in addition to nickel having a valence of +3. Then, in the oxidation reaction during charging, two-electron oxidation with Ni ²⁺ → Ni ⁴⁺ + 2e ⁻ also occurs. Therefore, it can be said that the NCMo oxide of the present invention has a large charge / discharge capacity.

In the NCMo oxide of the present invention, the element that preferentially contributes to the redox reaction during charging and discharging is considered to be nickel. Therefore, the value of b in the general formula (1) is the capacity of the NCMo oxide of the present invention. It is a value that greatly affects.
b preferably satisfies 0.6 ≦ b ≦ 0.97, more preferably 0.7 ≦ b ≦ 0.97, and more preferably 0.8 ≦ b ≦ 0.96. More preferred.

In the general formula (1), c preferably satisfies 0.01 ≦ c ≦ 0.3, more preferably 0.02 ≦ c ≦ 0.2, and 0.03 ≦ c ≦ 0. It is more preferable to satisfy .15, and it is particularly preferable to satisfy 0.04 ≦ c ≦ 0.1.
In the general formula (1), d preferably satisfies 0.001 ≦ d ≦ 0.3, more preferably 0.003 ≦ d ≦ 0.2, and 0.004 ≦ d ≦ 0. It is more preferable to satisfy 1. 1, and it is particularly preferable to satisfy 0.005 ≦ d ≦ 0.05.
When the values of c and d fluctuate greatly, the size of the primary particles of the NCMo oxide of the present invention may change significantly, or the space group of the crystal structure may change.

The values a, e, f, and g may be values within the range specified by the general formula (1), and preferably 0.5 ≦ a ≦ 1.5, 0 <e ≦ 0.15, 1.8 ≦. f ≦ 2.1, 0 <g ≦ 0.15, more preferably 0.8 ≦ a ≦ 1.3, 0 <e ≦ 0.1, 1.9 ≦ f ≦ 2.1, 0 <g ≦ 0 .1 can be exemplified.

D in the general formula (1) is a doping element, which is an element capable of improving the characteristics of the NCMo oxide of the present invention. F in the general formula (1) is also an element capable of improving the characteristics of the NCMo oxide of the present invention.

The following general formula (1-1) can be mentioned as a preferable aspect of the general formula (1).
General formula (1-1) Li _a Ni _b Co _c Mod _D ¹ _e1 D ² _e2 Of _{F g}
In the general formula (1-1), a, b, c, d, e1, e2, f, g are 0.5 ≦ a ≦ 2, 0.5 ≦ b ≦ 0.97, 0 <c <0. 5, 0 <d <0.5, 0 ≦ e1 ≦ 0.2, 0 ≦ e2 <0.2, 0 <e1 + e2 ≦ 0.2, b + c + d + e1 + e2 = 1, 1.8 ≦ f ≦ 2.2, 0 ≦ Satisfy g ≦ 0.2.
D ¹ is Zr, Ca, V, Mn, Cu, Ni, Sn, Tl, Fe, Sr, Ti, Ba, Mo, Y, rare earth elements, Os, Ir, Cd, Re, Bi, Rh, W, Cr, It is at least one element selected from Co, Zn, In, Al, Li, Na, Pb, Ru, and Nb.
D ² is an element other than Li, Ni, Co, Mo, D ¹ , O, and F.

For the preferred ranges of a, b, c, d, f and g in the general formula (1-1), the description in the general formula (1) is incorporated.

D ¹ in the general formula (1-1) is a doping element capable of particularly preferably improving the characteristics of the NCMo oxide of the present invention. e1 preferably satisfies 0.0001 ≦ e1 ≦ 0.2, more preferably 0.001 ≦ e1 ≦ 0.2, and more preferably 0.01 ≦ e1 ≦ 0.15. More preferred. In addition, e1 may be 0, and 0 <e1 ≦ 0.2 may be satisfied.

D ² in the general formula (1-1) is a doping element capable of suitably improving the characteristics of the NCMo oxide of the present invention. As D ² , at least one element selected from Na and P is preferable.
Examples of the range of e2 in the general formula (1-1) include 0 <e2 ≦ 0.1, 0 <e2 ≦ 0.0005, and 0 <e2 ≦ 0.01. Note that e2 may be 0.

Next, the method for producing the NCMo oxide of the present invention will be described.

One aspect of the method for producing NCMo oxide of the present invention is
Steps to prepare transition metal hydroxides containing nickel, cobalt and molybdenum,
A step of heating a transition metal hydroxide to remove adhering water or to make a transition metal oxide,
The present invention comprises a step of mixing a transition metal hydroxide from which adhering water has been removed or the transition metal oxide with a lithium salt and firing the mixture.

Further, a preferred embodiment of the method for producing an NCMo oxide of the present invention (hereinafter, may be referred to as “a suitable method for producing the present invention)) is described.
a) Steps of preparing transition metal hydroxides containing nickel, cobalt and molybdenum,
b) A step of heating the transition metal hydroxide to remove adhering water or to make it a transition metal oxide.
c) A step of coating a transition metal hydroxide from which adhering water has been removed or the transition metal oxide with a metal compound to form a coated body.
d) It has a step of mixing the coated body and a lithium salt and firing.

D ¹ in the general formula (1-1) is a metal mainly derived from the metal compound in step c).
D ² is an element derived mainly from a compound that can be added in steps a) and / or d).

In the preferred production method of the present invention, the transition metal hydroxide or the particles of the transition metal oxide are coated with the metal compound in the c) step, and the metal compound in the coated portion is formed in the subsequent d) step. It is thought that it acts as a barrier and suppresses the movement of nickel inside the particles to the lithium sites of the layered rock salt structure. That is, in the NCMo oxide produced by the suitable production method of the present invention, it is considered that the proportion of nickel correctly present at the transition metal site that should originally exist is higher than that of the conventional one.
As a result, the lithium ion secondary battery provided with the positive electrode having the suitable NCMo oxide of the present invention exhibits suitable battery characteristics.

Hereinafter, suitable production methods of the present invention will be described in order from a) step. Unless otherwise specified, the pH specified in the present specification refers to a value measured at 25 ° C.

First, a) a step will be described. a) The step is a step of preparing a transition metal hydroxide containing nickel, cobalt and molybdenum.

The transition metal hydroxide containing nickel, cobalt and molybdenum used in the step can be produced by mixing an aqueous solution containing nickel, cobalt and molybdenum with a basic aqueous solution to precipitate a transition metal hydroxide. .. The manufacturing process of such a transition metal hydroxide will be described in detail.

The manufacturing process of transition metal hydroxides is
A step of dissolving a nickel salt, a cobalt salt and a molybdenum compound in water to prepare a transition metal-containing aqueous solution containing nickel, cobalt and molybdenum in a predetermined ratio.
The process of preparing a basic aqueous solution,
The transition metal hydroxide precipitation step of supplying the transition metal-containing aqueous solution to the basic aqueous solution and precipitating nickel, cobalt and molybdenum as transition metal hydroxides is included.

Examples of the nickel salt include nickel sulfate, nickel carbonate, nickel nitrate, nickel acetate, and nickel chloride. Examples of the cobalt salt include cobalt sulfate, cobalt carbonate, cobalt nitrate, cobalt acetate, and cobalt chloride. Examples of the molybdenum compound include molybdic acids such as H ₂ MoO ₄ , Li ₂ MoO ₄ , Na ₂ MoO ₄ , K ₂ MoO ₄ , (NH ₄ ) ₂ MoO ₄ , and salts thereof, and molybdenum oxide. ..

The compounding ratio of the nickel salt, the cobalt salt and the molybdenum compound in the transition metal-containing aqueous solution may be adjusted so that the compounding ratio thereof becomes the metal composition ratio of the desired NCMo oxide.

The step of preparing the transition metal-containing aqueous solution is preferably performed in a reaction vessel equipped with a stirrer, and more preferably performed in a reaction vessel equipped with an apparatus capable of introducing an inert gas such as nitrogen or argon. Further, a reaction vessel equipped with an apparatus under constant temperature conditions is more preferable.

The transition metal-containing aqueous solution is preferably heated in the range of 40 to 90 ° C, more preferably 40 to 80 ° C.

The pH of the basic aqueous solution is preferably in the range of 9 to 14, more preferably in the range of 10 to 13, and even more preferably in the range of 10.5 to 12. The basic compound that can be used may be any compound that is soluble in water and exhibits basicity. For example, alkali metal hydroxides such as ammonia, sodium hydroxide, potassium hydroxide and lithium hydroxide, sodium carbonate and carbonic acid. Alkali metal carbonates such as potassium and lithium carbonate, alkali metal phosphates such as trisodium phosphate, tripotassium phosphate and trilithium phosphate, and alkali metal acetates such as sodium acetate, potassium acetate and lithium acetate. Can be done. The basic compound may be used alone or in combination of two or more. In the following steps, the pH of the aqueous solution is preferably kept in a suitable range, and therefore the basic aqueous solution preferably contains at least a basic compound having a buffering ability. Examples of the basic compound having a buffering capacity include ammonia, an alkali metal carbonate, an alkali metal phosphate, and an alkali metal acetate.

The step of preparing the basic aqueous solution is preferably carried out in a reaction vessel equipped with a stirrer, and more preferably carried out in a reaction vessel equipped with an apparatus capable of introducing an inert gas such as nitrogen or argon. Further, a reaction vessel equipped with an apparatus under constant temperature conditions is more preferable.

The basic aqueous solution is preferably heated in the range of 40 to 90 ° C, more preferably 40 to 80 ° C.

In the transition metal hydroxide precipitation step, by supplying the transition metal-containing aqueous solution to the basic aqueous solution, the metal ions react with the hydroxide ions, and nickel, cobalt and molybdenum having low solubility in water are reacted. A transition metal hydroxide containing is formed and precipitates. Strictly speaking, it is considered that precipitates may be formed in the presence of both transition metal hydroxides and metal compounds that are not hydroxides, but here, such precipitates are collectively referred to. , Called transition metal hydroxide. Precipitated transition metal hydroxide particles form the basis of NCMo oxide primary particles. Therefore, if the transition metal hydroxide precipitation step is performed under conditions where the precipitation rate of the transition metal hydroxide is extremely high, that is, conditions where nuclei of the transition metal hydroxide occur everywhere, the transition metal hydroxide is disordered. Particles will be formed, which can result in unwanted crystallization of NCMo oxide primary particles. Therefore, in the transition metal hydroxide precipitation step, it is preferable to precipitate the transition metal hydroxide particles under the mildest possible conditions.

From the above viewpoint, the rate of supplying the transition metal-containing aqueous solution is preferably 10 to 1000 mL / h, more preferably 20 to 500 mL / h, and particularly preferably 50 to 300 mL / h.

In the transition metal hydroxide precipitation step, it is preferable to keep the reaction solution at a constant pH. The pH value here means the value itself obtained by measuring the reaction solution with a pH meter. The pH is preferably in the range of 9 to 14, more preferably in the range of 10 to 12, and particularly preferably in the range of 10.5 to 11. In order to keep the reaction solution at a constant pH, it is preferable to prepare another basic aqueous solution and appropriately add it to the reaction solution in the transition metal hydroxide precipitation step.

The transition metal hydroxide precipitation step is preferably carried out in a reaction vessel equipped with a stirrer, and more preferably carried out in a reaction vessel equipped with an apparatus capable of introducing an inert gas such as nitrogen or argon. Further, a reaction vessel equipped with an apparatus under constant temperature conditions is more preferable.

In the transition metal hydroxide precipitation step, it is preferable that the amount of dissolved oxygen present in the reaction system is small. If the amount of dissolved oxygen present in the reaction system is large, an unfavorable oxidation reaction may occur, or suitable crystallization of the transition metal hydroxide accompanying precipitation of the transition metal hydroxide may be hindered.

In order to reduce the amount of dissolved oxygen present in the reaction system, the transition metal hydroxide precipitation step is performed under heating, while introducing an inert gas into the reaction system, an oxygen scavenger, It is preferable to carry out in the presence of a reducing agent, an antioxidant and the like.

As the heating condition, the range of 40 to 90 ° C. and 60 to 80 ° C. can be exemplified.
Examples of the inert gas include nitrogen, argon and helium.
Deoxidizers, reducing agents, antioxidants include ascorbic acid and its salts, glyoxylic acid and its salts, hydrazine, dimethylhydrazine, hydroquinone, dimethylamineboran, NaBH ₄ , NaBH ₃ CN, KBH ₄ , sulfite and its salts. , Thiosulfate and its salt, Pyro sulfite and its salt, Hypophosphate and its salt, Hypophosphate and its salt can be exemplified.

After the transition metal hydroxide precipitation step, the transition metal hydroxide is separated by filtration or the like. By the above method, a transition metal hydroxide can be obtained.

In step a), the compound containing the element D ² in the general formula (1-1) may be added to produce a transition metal hydroxide containing D ² .

Next, b) the step will be described. b) The step is a step of heating the transition metal hydroxide containing nickel to remove the adhering water or to make the transition metal oxide.
The heating temperature is preferably in the range of 100 to 800 ° C, more preferably in the range of 200 to 700 ° C, and particularly preferably in the range of 300 to 600 ° C. b) The step may be carried out under normal pressure or under reduced pressure.

Next, the c) step will be described. c) The step is a step of coating a transition metal hydroxide or a transition metal oxide from which adhering water has been removed with a metal compound to form a coated body.
Hereinafter, a case where the “transition metal oxide” is coated with a metal compound will be described. In the case of coating the "transition metal hydroxide from which the adhering water has been removed" with a metal compound, the "transition metal oxide" is appropriately appropriate to the "transition metal hydroxide from which the adhering water has been removed" in the following description. It should be read as.

Specific examples of the metal compound include hydroxide of D ¹ , for example, ZrO ₂ , CaVO ₃ , MnO ₂ , La ₂ CuO ₄ , La ₂ NiO ₄ , SnO ₂ , Tl ₂ Mn ₂ O ₇ , EuO, Fe. _{2O 3} , CamnO ₃ , SrMnO ₃ , (Sr, La) TiO ₃ , LaTIO ₃ , SrFeO ₃ , BaMoO ₃ , CaMoO ₃ , Ln ₂ Os ₂ O ₇ (Ln is an element selected from Y and rare earth elements. ), Tl ₂ Ir ₂ O ₇ , Cd ₂ Re ₂ O ₇ , Lu ₂ Ir ₂ O ₇ , Bi ₂ Rh ₂ O ₇ , Bi ₂ Ir ₂ O ₇ , Ti ₂ O ₃ , WO ₂ , VO, V ₂ O ₃ , LaMnO ₃ , CaCrO ₃ , LaCoO ₃ , (ZnO) ₅ , SrCrO ₃ , In _0.97 Y _0.03 O ₃ , Zn _x Al _y O (x + y = 1), LiV ₂ O ₄ , Na _{1- x} CoO ₂ (0 <x <1), LiTi ₂ O ₄ , SrMoO ₃ , BaPbO ₃ , Tl ₂ Os ₂ O ₇ , Pb ₂ Os ₂ O ₇ , Pb ₂ Ir ₂ O ₇ , Lu ₂ Ru ₂ O ₇ , Bi ₂ Ru ₂ O ₇ , SrRuO ₃ , CaRuO ₃ , CrO ₂ , MoO ₂ , ReO ₂ , TiO, LaO, _SmO , LaNiO ₃ , SrVO ₃ , ReO ₃ , IrO ₂ , RuO ₂ , RhO ₂ , O , NbO, La _{2O 3} , NiO, LaSr _x Coy O ₃ (x + _y = 1), NaCoO ₃ , NaNiO ₃ , LiCoO ₃ , metal oxides selected from LiNiO ₃ or metal hydroxides of their precursors. Can be exemplified.
Among the metal compounds, the metal oxide preferably has a crystal structure such as a perovskite type.

To coat the transition metal oxide with a metal compound, a method may be adopted in which a precursor of each metal compound or an aqueous solution in which each metal is dissolved is sprayed on the transition metal oxide and then / or simultaneously dried. .. Further, the transition metal oxide is immersed in the precursor of each metal compound or the aqueous solution in which each metal is dissolved, and the precursor of each metal compound or the hydroxide of each metal is adhered to the surface of the transition metal oxide. After that, a method of heating and drying may be adopted. In particular, the dispersion liquid of the transition metal oxide is mixed with the precursor of each metal compound and the aqueous solution in which each metal is dissolved to precipitate the hydroxide of each metal on the surface of the transition metal oxide, and then dried. (Hereinafter, it may be referred to as a precipitation method) is preferably adopted.

Hereinafter, a suitable precipitation method when D ¹ is Zr will be described in detail. The precipitation method has the following steps c-1), c-2) and c-3). When D ¹ is a metal other than Zr, the zirconium in the steps c-1), c-2) and c-3) may be read as the metal. When D ¹ is a plurality of metals, an aqueous solution containing a plurality of metals may be used in step c-2), or while changing the metal type of the metal aqueous solution, step c-1). The steps c-2) and c-3) may be repeated.

c-1) Dispersion liquid preparation step of dispersing transition metal oxides in water,
c-2) A zirconium precipitation step of mixing a zirconium aqueous solution containing a heteroelement-containing organic compound with the dispersion liquid to precipitate zirconium hydride on the surface of the transition metal oxide.
c-3) A step of drying a transition metal oxide having zirconium hydride deposited on the surface to form a coated body.

c-1) It is preferable to pulverize the transition metal oxide before the step. Further, it is preferable to adjust the pH so that the pH of the dispersion is in the range of about 9 to 12.

Next, the c-2) step will be described.
A zirconium aqueous solution containing a hetero element-containing organic compound is produced by dissolving a zirconium salt and a hetero element-containing organic compound in water. Aqueous zirconium solution containing a hetero element-containing organic compound is usually an acidic solution. The blending ratio of the zirconium salt and the hetero element-containing organic compound is preferably in the range of zirconium: hetero element-containing organic compound = 1: 1 to 1: 3 in terms of molar ratio.

Examples of the zirconium salt include zirconium oxide, zirconium hydroxide, zirconium sulfate, zirconium nitrate, zirconium phosphate, and zirconium halide.

The hetero element in the hetero element-containing organic compound means N, O, P or S. Examples of the hetero element-containing organic compound include an amino group, an amide group, an imide group, an imino group, a cyano group, an azo group, a hydroxyl group, an alkoxy group, a carboxyl group, an ester group, an ether group, and a carbonyl group, which can be coordinated with a metal ion. Phosphoic acid group, phosphoric acid ester group, phosphonic acid group, phosphonic acid ester group, phosphinic acid group, phosphinic acid ester group, phosphenic acid group, phosphenic acid ester group, phosphenic acid group, subphosphenic acid ester group, thiol group, Examples thereof include organic compounds having a sulfide group, a sulfinyl group, a sulfonyl group, a sulfonic acid group, a thiocarboxyl group, a thioester group or a thiocarbonyl group.

In particular, as the hetero element-containing organic compound, a chelate compound having a plurality of the above groups and capable of coordinating to a metal ion at a plurality of locations is preferable.

Specific examples of the chelate compound include polyamine compounds such as ethylenediamine and diethylenetriamine, amino acids such as glycine, alanine, cysteine, glutamine, arginine, aspartic acid, aspartic acid, serine and ethylenediamine tetraacetic acid, malonic acid, succinic acid, glutaric acid and malein. Examples thereof include dicarboxylic acids such as acids and phthalic acids, and hydroxycarboxylic acids.

As the chelating compound, hydroxycarboxylic acid is particularly preferable. Examples of the hydroxycarboxylic acid having a hydroxyl group and a carboxylic acid group in the molecule include an aliphatic hydroxycarboxylic acid and an aromatic hydroxycarboxylic acid.

The aliphatic hydroxycarboxylic acids include glycolic acid, lactic acid, tartronic acid, glyceric acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, γ-hydroxybutyric acid, malic acid, tartrate acid, citramalic acid, citric acid, isocitrate and leucic acid. , Mevalonic acid, pantoic acid, quinic acid, shikimic acid can be exemplified.

Examples of the aromatic hydroxycarboxylic acid include o-hydroxybenzoic acid derivatives such as salicylic acid, gentisic acid and orceric acid, mandelic acid, benzylic acid and 2-hydroxy-2-phenylpropionic acid.

All of the above-mentioned specific hydroxycarboxylic acids can form a conformation in which an OH group and a CO ₂ H group can be coordinated with the same zirconium ion.

In the c-2) step, it is preferable to control the pH of the mixed solution in the c-2) step in order to efficiently precipitate zirconium. Here, it is assumed that zirconium hydride having low solubility is deposited on the surface of the transition metal oxide by setting the pH of the mixed solution to the alkaline side. For example, it is preferable to add a basic aqueous solution so that the pH of the solution in step c-2) is in the range of 9 to 13. As the basic aqueous solution, the one described in step a) may be adopted.

The transition metal oxide that has undergone the c-2) step is separated by a method such as filtration and is subjected to the c-3) step.

The drying in the c-3) step is preferably carried out under heating and / or under reduced pressure. The heating temperature can be exemplified in the range of 100 to 500 ° C. and 200 to 400 ° C.
The main purpose of the drying in the c-3) step is to remove the water adhering to the transition metal oxide having zirconium hydride deposited on the surface. However, by raising the heating temperature, zirconium hydride existing on the surface of the transition metal oxide may be dehydrated and changed to zirconium oxide. That is, the coated body may be a transition metal oxide coated with zirconium hydride or a transition metal oxide coated with zirconium oxide.

Next, d) the step will be described. d) The step is a step of mixing the coated body and the lithium salt and firing.

Examples of the lithium salt include lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate, lithium oxalate, and lithium halide. Lithium carbonate is preferably used as the lithium salt because of its low cost and excellent performance of the produced NCMo oxide.
The blending amount of the lithium salt may be appropriately determined so as to obtain an NCMo oxide having a desired lithium composition.

Examples of the mixing device include a mortar and pestle, a stirring mixer, a V-type mixer, a W-type mixer, a ribbon-type mixer, a drum mixer, and a ball mill.

d) In the step, the compound containing the element of D ² in the general formula (1-1) may be mixed. In particular, it is preferable that a compound selected from Na compound, F compound and P compound is mixed. Due to the presence of D ² , the rate characteristics and / or the capacity retention rate of the lithium ion secondary battery provided with the NCMo oxide of the present invention can be expected to be improved.

Examples of the Na compound include sodium salts such as NaF, NaCl, NaCl, NaI, Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ SO ₄ , NaHSO ₄ , NaNO ₃ , and CH ₃ CO ₂ Na. can.
Examples of the F compound include metal fluorides such as LiF, NaF, KF, MgF ₂ , CaF ₂ , BaF ₂ , and AlF ₃ .
Examples of P compounds include H ₃ PO ₄ , LiH ₂ PO ₄ , Li ₂ HPO ₄ , Li ₃ PO ₄ , NaH ₂ PO ₄ , Na ₂ HPO ₄ , Na ₃ PO ₄ , KH ₂ PO ₄ , K ₂ HPO ₄ , Phosphoric acid and phosphate such as K ₃ PO ₄ can be exemplified.

The firing may be carried out in an atmospheric atmosphere or an oxygen gas atmosphere, or may be carried out in the presence of an inert gas such as helium or argon. The heating temperature in the firing step can be exemplified in the range of 400 to 1200 ° C. The heating time in the firing step can be exemplified by 1 to 50 hours.

d) The firing in the step may be carried out under a single temperature condition, may be carried out by combining a plurality of firing steps having different temperature conditions, or may be carried out by setting a specific temperature raising program. You may.

As a method of combining a plurality of firing steps having different temperature conditions, the first firing step of heating the mixture of the coated body and the lithium salt at 400 to 800 ° C. to obtain the first fired body, and the first fired body are used. A second firing step of heating at 550 to 1000 ° C. can be mentioned. By combining a plurality of firing steps, NCMo oxide that can be a suitable active material can be produced.

The temperature in the first firing step can be exemplified in the range of 400 to 800 ° C. and 650 to 750 ° C. The heating time of the first firing step can be exemplified in the range of 3 to 30 hours, 5 to 20 hours, and 5 to 15 hours.

The second firing step is a step of heating the first fired body at 550 to 1000 ° C.
Here, from the point of view of crystal formation of NCMo oxide, it is easier to form crystals having a uniform composition and a uniform shape by heating at a low temperature as much as possible. Therefore, the temperature in the second firing step can be exemplified in the range of 550 to 950 ° C., 550 to 900 ° C., 550 to 850 ° C., and 550 to 800 ° C.

The heating time of the second firing step can be exemplified in the range of 3 to 30 hours, 5 to 20 hours, and 5 to 15 hours.

In the preferred production method of the present invention, since the particles of the transition metal oxide are coated with the metal compound in the c) step, the coated metal compound serves as a barrier in the first firing step and the second firing step. It is considered that nickel is suppressed from moving to the lithium site of the layered rock salt structure.

d) It is preferable that the NCMo oxide obtained in the step has a constant particle size distribution through a pulverization step and a classification step. As for the range of the particle size distribution, the average particle size (D ₅₀ ) is preferably 50 μm or less, more preferably 1 μm or more and 30 μm or less, and further preferably 1 μm or more and 20 μm or less in the measurement with a general laser scattering diffraction type particle size distribution meter. 2, μm or more and 10 μm or less are particularly preferable.

Further, another preferable aspect of the method for producing NCMo oxide of the present invention is
a'-1) Step of preparing a transition metal hydroxide containing nickel and cobalt,
a'-2) A step of adding an aqueous solution of molybdic acid or a salt thereof to a basic suspension containing a transition metal hydroxide.
a'-3) A step of lowering the pH of the suspension after adding an aqueous solution of molybdic acid or a salt thereof to precipitate molybdate on the surface of the transition metal hydroxide to form a coated body.
b') The step of heating the coated body to remove adhering water or to make a transition metal oxide,
d') It has a step of mixing a transition metal hydroxide or a transition metal oxide from which adhering water has been removed with a lithium salt and firing the mixture.
The technical matters for specifying each step are the a) step or c) step described above for the a'-1) to a'-3) steps, and the b) step described above for the b') step. For the d') step, the technical contents of the d) step described above are appropriately and appropriately incorporated.

Furthermore, another preferred embodiment of the method for producing NCMo oxide of the present invention is
a'') Step of preparing transition metal hydroxides containing nickel and cobalt,
b'') The step of heating the transition metal hydroxide to remove the adhering water or to make it a transition metal oxide,
c'') Transition metal hydroxide or transition metal oxidation by adding an aqueous solution of molybdic acid or a salt thereof to a suspension containing transition metal hydroxide or transition metal oxide from which adhering water has been removed. The process of coating an object with molybdenate to form a coated body,
d'') It has a step of mixing the coated body and a lithium salt and firing.
The technical matters for specifying each process are a'') step described above for step a), b'') step described above for step b), and c'') step described above. For the c) step and the a'-2) step, the a'-3) step, and the d'') step, the technical contents of the d) step described above are appropriately and appropriately incorporated.

In the production method of the preceding paragraph, molybdenum is added in step a'-2) and integrated with the transition metal hydroxide containing nickel and cobalt in step a'-3). In the production method of the preceding paragraph, molybdenum is integrated with the transition metal hydroxide containing nickel and cobalt in step c'').
Here, in the steps a'-1) and a'') without molybdenum added, it is considered that the crystal growth of the transition metal hydroxide containing nickel and cobalt proceeds smoothly. The reason is that when a transition metal hydroxide containing nickel, cobalt and molybdenum is produced at once by the co-precipitation method, the molybdenum acid ion composed of hexavalent molybdenum is the hydroxylation of nickel. This is because it is considered that the oxyhydroxide of nickel may be formed by partially oxidizing the substance, and as a result, it is assumed that the crystal growth of the transition metal hydroxide is hindered.
Since the crystal size of the transition metal hydroxide as an intermediate is considered to be the basis of the size of the primary particles of the NCMo oxide of the present invention, it is produced by the production method of the preceding paragraph and the production method of the preceding paragraph. It can be said that the NCMo oxide of the present invention contained in the NCMo oxide contains relatively large primary particles. The NCMo oxide of the present invention containing large primary particles is expected to have low resistance.

The size of the primary particles of NCMo oxide is preferably in the range of 50 nm to 1000 nm, more preferably in the range of 100 nm to 500 nm, and further preferably in the range of 150 nm to 500 nm as observed under a microscope. The primary particle means a particle recognized as one particle at the time of SEM observation.

The NCMo oxide of the present invention can be used as an active material for a lithium ion secondary battery. The lithium ion secondary battery of the present invention comprises the NCMo oxide of the present invention as an active material. Specifically, the lithium ion secondary battery of the present invention includes a positive electrode, a negative electrode, a solid electrolyte or an electrolytic solution, and a separator having the NCMo oxide of the present invention as a positive electrode active material.

The positive electrode has a current collector and a positive electrode active material layer bonded to the surface of the current collector.

A current collector is a chemically inert electron conductor that keeps current flowing through the electrodes during the discharge or charging of a lithium-ion secondary battery. Collectors include at least one selected from silver, copper, gold, aluminum, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, and stainless steel. Metallic materials can be exemplified. The current collector may be covered with a known protective layer. A current collector whose surface is treated by a known method may be used as the current collector.

The current collector can take the form of a foil, a sheet, a film, a linear shape, a rod shape, a mesh, or the like. Therefore, as the current collector, for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, or a stainless steel foil can be preferably used. When the current collector is in the form of a foil, a sheet, or a film, the thickness thereof is preferably in the range of 1 μm to 100 μm.

The positive electrode active material layer contains a positive electrode active material and, if necessary, a conductive auxiliary agent and / or a binder.

The positive electrode active material may be any as long as it contains the NCMo oxide of the present invention, and only the NCMo oxide of the present invention may be adopted, or the NCMo oxide of the present invention and a known positive electrode active material may be used in combination. You may.

As an example of a known positive electrode active material, a spinel structure compound such as LiMn ₂ O ₄ , general formula: _LiMh PO ₄ (M is Mn, Fe, Co, Ni, Cu, Mg, Zn, V, Ca, Sr, Ba). , Ti, Al, Si, B, Te and Mo, at least one element, an olivine structural compound represented by 0 <h <2), LiMVO ₄ or Li ₂ MSiO ₄ (M in the formula is Co, Ni). , Mn, selected from at least one of Fe), a tabolinate compound represented by LiMPO ₄ F (M is a transition metal), and LiMBO ₃ (M is a transition metal). Examples thereof include a copper-based compound, Li ₂ MnO ₃ .

Conductivity aids are added to increase the conductivity of the electrodes. Therefore, the conductive auxiliary agent may be arbitrarily added when the conductivity of the electrode is insufficient, and may not be added when the conductivity of the electrode is sufficiently excellent. The conductive auxiliary agent may be a chemically inert electron high conductor, and examples thereof include carbon black, which are carbonaceous fine particles, graphite, Vapor Grown Carbon Fiber, and various metal particles. To. Examples of carbon black include acetylene black, Ketjen black (registered trademark), furnace black, and channel black. These conductive auxiliary agents can be added to the active material layer alone or in combination of two or more.

The mixing ratio of the conductive auxiliary agent in the active material layer is preferably 1: 0.01 to 1: 0.5, preferably 1: 0.01 to 1: 0, in terms of mass ratio. It is more preferably .2, and even more preferably 1: 0.03 to 1: 0.1. This is because if the amount of the conductive auxiliary agent is too small, an efficient conductive path cannot be formed, and if the amount of the conductive auxiliary agent is too large, the formability of the active material layer is deteriorated and the energy density of the electrode is lowered.

The binder serves to anchor the active material and the conductive auxiliary agent to the surface of the current collector and maintain the conductive network in the electrode. Examples of the binder include fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide-based resins such as polyimide and polyamideimide, resins containing an alkoxysilyl group, and poly (poly). Examples thereof include acrylic resins such as meta) acrylic acid, styrene-butadiene rubber (SBR), and carboxymethyl cellulose. These binders may be used alone or in combination of two or more.

The mixing ratio of the binder in the active material layer is preferably 1: 0.001 to 1: 0.3, preferably 1: 0.005 to 1: 0, in terms of mass ratio. It is more preferably .2, and even more preferably 1: 0.01 to 1: 0.15. This is because if the amount of the binder is too small, the moldability of the electrode is lowered, and if the amount of the binder is too large, the energy density of the electrode is lowered.

The negative electrode has a current collector and a negative electrode active material layer bonded to the surface of the current collector. As the current collector, the one described in the positive electrode may be appropriately adopted. The negative electrode active material layer contains a negative electrode active material and, if necessary, a conductive auxiliary agent and / or a binder.

As the negative electrode active material, a known material may be adopted, and examples thereof include a carbon-based material capable of occluding and releasing lithium, an element capable of alloying with lithium, and a compound having an element capable of alloying with lithium. ..

Examples of the carbon-based material include non-graphitizable carbon, graphite, cokes, graphites, glassy carbons, calcined organic polymer compounds, carbon fibers, activated carbon, and carbon blacks. Here, the organic polymer compound calcined body refers to a polymer material such as phenols and furans that is calcined at an appropriate temperature and carbonized.

Specific elements that can be alloyed with lithium include Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, and Si. , Ge, Sn, Pb, Sb, Bi can be exemplified, and Si or Sn is particularly preferable.

Specific examples of the compound having an element that can be alloyed with lithium include ZnLiAl, AlSb, SiB ₄ , SiB ₆ , Mg ₂ Si, Mg ₂ Sn, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , and NiSi ₂ . CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v) ≦ 2), SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSiO or LiSnO can be exemplified, and in particular, SiO _x (0.3 ≦ x ≦ 1.6 or 0.5 ≦ x ≦ 1.5). Is preferable.

Among them, the negative electrode active material preferably contains a Si-based material having Si. The Si-based material is preferably composed of silicon or / or a silicon compound capable of occluding / releasing lithium ions, and for example, SiO _x (0.5 ≦ x ≦ 1.5) is preferable. Although silicon has a large theoretical charge / discharge capacity, silicon has a large volume change during charge / discharge. Therefore, by using SiO _x containing silicon as the negative electrode active material, it is possible to alleviate the volume change of silicon.

As the negative electrode active material, a Si material obtained by heating layered polysilane obtained by treating CaSi ₂ with an acid such as hydrochloric acid or hydrofluoric acid at 300 to 1000 ° C. may be adopted. Further, the Si material may be heated together with a carbon source and coated with carbon as the negative electrode active material.

As the negative electrode active material, one or more of the above can be used.

As for the conductive auxiliary agent and the binder used for the negative electrode, those described for the positive electrode may be appropriately and appropriately adopted in the same blending ratio.

In order to form the active material layer on the surface of the current collector, a conventionally known method such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method is used to collect electricity. The active substance may be applied to the surface of the body. Specifically, an active material, a solvent, and if necessary, a binder and / or a conductive auxiliary agent are mixed to prepare a slurry. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. The slurry is applied to the surface of the current collector and then dried. In order to increase the electrode density, the dried one may be compressed.

As the solid electrolyte, one that can be used as a solid electrolyte for a lithium ion secondary battery may be appropriately adopted.

The electrolytic solution contains a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent.

As the non-aqueous solvent, cyclic carbonates, cyclic esters, chain carbonates, chain esters, ethers and the like can be used. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, and examples of the cyclic ester include gamma-butyrolactone, 2-methyl-gamma-butyrolactone, acetyl-gamma-butyrolactone, and gamma-valerolactone. Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, and ethylmethyl carbonate, and examples of the chain ester include propionic acid alkyl ester, malonic acid dialkyl ester, and acetate alkyl ester. Examples of ethers include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane. As the non-aqueous solvent, a compound in which some or all of the chemical structure of the specific solvent is replaced with fluorine may be adopted.

Examples of the electrolyte include lithium salts such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (FSO ₂ ) ₂ , and LiN (CF ₃ SO ₂ ) ₂ .

Examples of the electrolytic solution include a solution in which a lithium salt is dissolved in a non-aqueous solvent such as ethylene carbonate, dimethyl carbonate, propylene carbonate, and diethyl carbonate at a concentration of about 0.5 mol / L to 1.7 mol / L.

The separator separates the positive electrode and the negative electrode, and allows lithium ions to pass through while preventing a short circuit due to contact between the two electrodes. Separators include polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide, synthetic resins such as polyaramid (Aromatic polyamide), polyester and polyacrylonitrile, polysaccharides such as cellulose and amylose, and natural products such as fibroin, keratin, lignin and sverin. Examples thereof include a porous body using one or more electrically insulating materials such as polymers and ceramics, a non-woven fabric, and a woven fabric. Further, the separator may have a multi-layer structure.

Next, an example of a method for manufacturing a lithium ion secondary battery will be described.

A separator is sandwiched between the positive electrode and the negative electrode as needed to form an electrode body. The electrode body may be either a laminated type in which a positive electrode, a separator and a negative electrode are stacked, or a wound type in which a positive electrode, a separator and a negative electrode are wound. After connecting from the positive electrode current collector and the negative electrode current collector to the positive electrode terminal and the negative electrode terminal leading to the outside using a current collecting lead or the like, an electrolytic solution is added to the electrode body to add a lithium ion secondary. Use a battery. Further, the lithium ion secondary battery of the present invention may be charged and discharged within a voltage range suitable for the type of active material contained in the electrode.

The shape of the lithium ion secondary battery of the present invention is not particularly limited, and various shapes such as a cylindrical type, a square type, a coin type, and a laminated type can be adopted.

The lithium ion secondary battery of the present invention may be mounted on a vehicle. The vehicle may be a vehicle that uses electric energy from a lithium ion secondary battery for all or part of its power source, and may be, for example, an electric vehicle or a hybrid vehicle. When a lithium ion secondary battery is mounted on a vehicle, it is advisable to connect a plurality of lithium ion secondary batteries in series to form an assembled battery. In addition to vehicles, devices equipped with lithium-ion secondary batteries include various battery-powered home appliances such as personal computers and portable communication devices, office equipment, and industrial equipment. Further, the lithium ion secondary battery of the present invention is used for wind power generation, solar power generation, hydraulic power generation and other power system power storage devices and power smoothing devices, power supply sources for ships and / or auxiliary machinery, aircraft, and aircraft. Power supply for spacecraft and / or auxiliary equipment, auxiliary power for vehicles that do not use electricity as a power source, power for mobile household robots, power for system backup, power for non-disruptive power supply, It may be used as a power storage device that temporarily stores the power required for charging in a charging station for an electric vehicle or the like.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. As long as it does not deviate from the gist of the present invention, it can be carried out in various forms with modifications, improvements, etc. that can be made by those skilled in the art.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to these examples.

(Example 1)
The NCMo oxide of Example 1 was produced as follows.

a) Step 83 g of nickel sulfate hexahydrate, 11.5 g of cobalt sulfate heptahydrate, and 3.6 g of disodium molybdic disodium dihydrate are dissolved in 400 mL of pure water to dissolve the transition metal. A contained aqueous solution was prepared. The molar ratio of nickel, cobalt and molybdenum in the transition metal-containing aqueous solution is 85: 11: 4.

30 g of 25% aqueous ammonia was mixed with pure water to prepare a 400 mL first basic aqueous solution.

Sodium hydroxide, aqueous ammonia and pure water were mixed to prepare a second basic aqueous solution having a pH of 10.75.

A transition metal-containing aqueous solution was supplied to the second basic aqueous solution under the conditions of introduction of nitrogen gas and stirring in a constant temperature bath maintained at 80 ° C., and nickel, cobalt and molybdenum were precipitated as transition metal hydroxides. .. At this time, in order to maintain the pH of the reaction solution in the range of 10.75 to 10.80, a first basic aqueous solution and a 48 wt% sodium hydroxide aqueous solution were appropriately added dropwise. The pH value here means the value itself obtained by measuring the reaction solution with a pH meter.

The transition metal hydroxide was separated by filtration. The transition metal hydroxide was washed with pure water using an ultrasonic cleaner, and then the transition metal hydroxide was isolated by filtration.

b) Step The transition metal hydroxide was heated at 300 ° C. for 5 hours in the atmosphere to obtain a transition metal oxide.

c) Step A transition metal oxide was added to pure water to prepare a dispersion of the transition metal oxide.

0.3 g of zirconium sulfate and 0.17 g of glycolic acid as a hydroxy carboxylic acid were dissolved in water to prepare a hydroxy carboxylic acid-containing zirconium aqueous solution. In the hydroxycarboxylic acid-containing zirconium aqueous solution, the molar ratio of zirconium to glycolic acid was 1: 2.

The dispersion liquid of the transition metal oxide and the aqueous zirconium solution containing hydroxycarboxylic acid were mixed to prepare a mixed liquid. Then, an aqueous sodium hydroxide solution was added over 1 hour until the pH of the mixed solution reached 12.5 to obtain a coated body in which zirconium hydride was precipitated on the surface of the transition metal oxide. The coat was separated by filtration and then dried.

d) Step 10 g of the coated body after drying, 2.12 g of lithium hydroxide anhydride, 0.13 g of Na ₃ PO ₄ and 0.023 g of LiF were mixed in a mortar to prepare a mixture. Then, the mixture was heated at 650 ° C. for 10 hours in an air atmosphere to obtain a first fired body.

The first calcined body was crushed in a mortar to obtain a powder. The powdery first calcined body was heated at 775 ° C. for 10 hours in an oxygen gas atmosphere to obtain NCMo oxide. The NCMo oxide was crushed in a mortar to obtain the NCMo oxide of Example 1.
The theoretical composition of the NCMo oxide of Example 1 is Li ₁ Ni _0.85 Co _0.11 Mo _0.04 Zr _0.0025 Na _0.01 P _0.01 O ₂ F _0.01 .

The lithium ion secondary battery of Example 1 was manufactured as follows.

An aluminum foil having a thickness of 20 μm was prepared as a current collector for the positive electrode. 94 parts by mass of NCMo oxide of Example 1 was mixed as a positive electrode active material, 3 parts by mass of acetylene black as a conductive auxiliary agent, and 3 parts by mass of polyvinylidene fluoride as a binder. This mixture was dispersed in an appropriate amount of N-methyl-2-pyrrolidone to prepare a slurry. The slurry was placed on the surface of the aluminum foil and applied using a doctor blade so that the slurry became a film. The aluminum foil coated with the slurry was dried at 80 ° C. for 20 minutes to remove N-methyl-2-pyrrolidone by volatilization, and a positive electrode active material layer was formed on the surface of the aluminum foil. The aluminum foil having the positive electrode active material layer formed on the surface was compressed using a roll press machine, and the aluminum foil and the positive electrode active material layer were firmly adhered to each other to form a bonded product. The joint was heated at 120 ° C. for 6 hours using a vacuum dryer and cut into a predetermined shape to obtain a positive electrode.

The negative electrode was manufactured as follows.
98.3 parts by mass of graphite was mixed with 1 part by mass of styrene-butadiene rubber and 0.7 parts by mass of carboxymethyl cellulose as a binder, and this mixture was dispersed in an appropriate amount of ion-exchanged water to prepare a slurry. This slurry was applied to a copper foil having a thickness of 20 μm, which is a current collector for a negative electrode, so as to form a film using a doctor blade, and the current collector to which the slurry was applied was dried and then pressed to form a bonded product. The joint was heated at 120 ° C. for 6 hours using a vacuum dryer and cut into a predetermined shape to obtain a negative electrode.

A laminated lithium ion secondary battery was manufactured using the above positive and negative electrodes. Specifically, a rectangular sheet having a thickness of 25 μm made of a resin film having a three-layer structure of polypropylene / polyethylene / polypropylene was sandwiched between the positive electrode and the negative electrode as a separator to form a group of electrode plates. This group of plates was covered with a set of two laminated films, the three sides were sealed, and then the electrolytic solution was injected into the bag-shaped laminated film. As the electrolytic solution, a solution in which LiPF ₆ was dissolved in a solvent obtained by mixing ethylene carbonate, ethylmethyl carbonate and dimethyl carbonate at a volume ratio of 3: 3: 4 so as to be 1 mol / L was used. Then, by sealing the remaining one side, the four sides were hermetically sealed, and the electrode plate group and the electrolytic solution were sealed to obtain the laminated lithium ion secondary battery of Example 1. The positive electrode and the negative electrode are provided with tabs that can be electrically connected to the outside, and a part of these tabs extends to the outside of the laminated lithium ion secondary battery.
Through the above steps, the lithium ion secondary battery of Example 1 was manufactured.

(Reference example 1)
Except for a) that 5 g of sodium tungstate dihydrate was used instead of 3.6 g of disodium tungstate dihydrate in the step, and d) the step was as follows. The lithium nickel cobalt tungsten oxide and lithium ion secondary battery of Reference Example 1 were produced in the same manner as in Example 1.

d) Step 10 g of the coated body after drying, 2.12 g of lithium hydroxide anhydride, 0.13 g of Na ₃ PO ₄ and 0.023 g of LiF were mixed in a mortar to prepare a mixture. Then, the mixture was heated at 650 ° C. for 5 hours in an air atmosphere to obtain a first fired body.

The first calcined body was crushed in a mortar to obtain a powder. The powdery first fired body was heated at 750 ° C. for 15 hours under an oxygen gas atmosphere to obtain a lithium nickel cobalt tungsten oxide. The lithium nickel cobalt tungsten oxide was crushed in a dairy pot to obtain the lithium nickel cobalt tungsten oxide of Reference Example 1.
The theoretical composition of the lithium nickel cobalt tungsten oxide of Reference Example 1 is Li ₁ Ni _0.85 Co _0.11 W _0.04 Zr _0.0025 Na _0.01 P _0.01 O ₂ F _0.01 . be.

(Comparative Example 1)
The lithium ion secondary battery of Comparative Example 1 was produced in the same manner as in Example 1 except that LiNi _0.85 Co _0.11 Al _0.04 O ₂ was adopted as the positive electrode active material.

(Evaluation example 1)
The cross-sectional observation of the secondary particles of NCMo oxide of Example 1 and the secondary particles of lithium nickel cobalt tungsten oxide of Reference Example 1 was carried out with a scanning electron microscope (SEM). FIG. 1 shows a cross-sectional SEM image of secondary particles in the NCMo oxide of Example 1.
According to the measurement by the SEM image, the primary particle diameter of NCMo oxide of Example 1 was about 500 nm, and the primary particle diameter of lithium nickel cobalt tungsten oxide of Reference Example 1 was about 50 nm.
It can be said that the primary particles of NCMo oxide of Example 1 are significantly larger than the primary particles of lithium nickel cobalt tungsten oxide of Reference Example 1. This result shows that in step a), the crystal growth in the precipitate of the transition metal hydroxide containing nickel, cobalt and molybdenum is higher than the crystal growth in the precipitate of the transition metal hydroxide containing nickel, cobalt and tungsten. However, it can be said that it suggests that it has progressed smoothly.

(Evaluation example 2)
The lithium ion secondary batteries of Example 1, Reference Example 1 and Comparative Example 1 were charged and discharged at a rate of 0.1 C by charging to 4.4 V and then discharging to 2.5 V.
Table 1 shows the discharge capacity per unit volume of the positive electrode active material.

It can be seen that the lithium ion secondary battery of Example 1 is superior in discharge capacity to the lithium ion secondary batteries of Reference Example 1 and Comparative Example 1.

(Example 2)
d) The NCMo oxide and lithium ion secondary batteries of Example 2 were produced in the same manner as in Example 1 except that the heating time at 775 ° C. in the step was changed to 5 hours.

(Example 3)
d) NCMo oxide and lithium ion secondary of Example 3 in the same manner as in Example 1 except that the 10-hour heating at 650 ° C. in the step was changed to the 5-hour heating at 700 ° C. Manufactured a battery.

(Example 4)
d) The NCMo oxide and lithium ion secondary battery of Example 4 were produced by the same method as in Example 2 except that lithium carbonate was used instead of lithium hydroxide anhydride in the step.
In order to make the amount of lithium element used equivalent to that of Example 2, the molar amount of lithium carbonate (Li ₂ CO ₃ ) used was halved with respect to the molar amount of lithium hydroxide (LiOH) used.

(Example 5)
d) NCMo of Example 5 in the same manner as in Example 4 except that the heating time at 650 ° C. in the step was changed to 15 hours and the heating time at 775 ° C. was changed to 10 hours. Oxide and lithium ion secondary batteries were manufactured.

(Example 6)
d) Same as Example 4 except that the 10-hour heating at 650 ° C. in the step was changed to 5 hours at 700 ° C. and the heating time at 775 ° C. was changed to 10 hours. The NCMo oxide and lithium ion secondary battery of Example 6 were produced by the method of.

(Evaluation example 3)
The lithium ion secondary batteries of Examples 1 to 6 were charged and discharged at a rate of 0.1 C by charging to 4.4 V and then discharging to 2.5 V. The results are shown in Table 2.

From Table 2, it can be said that the performance of NCMo oxide depends on the type of lithium salt used in step d) and the heating conditions in step d).
As shown in Examples 5 and 6, when lithium carbonate is used, an excellent volume of NCMo oxide can be produced.

Claims (9)

A lithium nickel cobalt molybdenum oxide represented by the following general formula ( 1-1 ).
General formula ( 1-1 ₎ Li _a Ni _b Co _c Mod _D ¹ _e1 D ² _{e2 Of} F g
In the general formula (1-1), a, b, c, d, e1, e2, f, g are 0.5 ≦ a ≦ 2, 0.5 ≦ b ≦ 0.97, 0 <c <0. 5, 0 <d <0.5, 0 <e1 ≦ 0.2, 0 ≦ e2 <0.2, 0 <e1 + e2 ≦ 0.2, b + c + d + e1 + e2 = 1, 1.8 ≦ f ≦ 2.2, 0 < Satisfy g ≦ 0.2.
D ¹ is Zr.
D ² is an element other than Li, Ni, Co, Mo, D ¹ , O, and F. The lithium nickel cobalt molybdenum oxide according to claim 1 , wherein D ² is at least one element selected from Na and P. The lithium nickel cobalt molybdenum oxide according to claim 1 or 2 , wherein D ² contains Na and P. A positive electrode containing the lithium nickel cobalt molybdenum oxide according to any one of claims 1 to 3 . A lithium ion secondary battery comprising the positive electrode of claim 4 . A method for producing a lithium nickel cobalt molybdenum oxide represented by the following general formula (1) .
Steps to prepare transition metal hydroxides containing nickel, cobalt and molybdenum,
A step of heating a transition metal hydroxide to remove adhering water or to make a transition metal oxide,
A step of coating a transition metal hydroxide from which adhering water has been removed or the transition metal oxide with a metal compound to form a coated body.
A production method comprising a step of mixing and firing the coated body and lithium carbonate.
General formula ₍ 1 ₎ Li _a Ni _b Co _c Mod _De Of F _g
In the general formula (1), a, b, c, d, e, f, g are 0.5 ≦ a ≦ 2, 0.5 ≦ b ≦ 0.97, 0 <c <0.5, 0 <. It satisfies d <0.5, 0 ≦ e ≦ 0.2, b + c + d + e = 1, 1.8 ≦ f ≦ 2.2, and 0 ≦ g ≦ 0.2. D is a dope element. The lithium nickel cobalt molybdenum oxide is
The manufacturing method according to claim 6, wherein the general formula (1) is the following general formula (1-1).
General formula (1-1) Li _a Ni _b Co _c Mo _d D ¹ _e1 D ² _e2 O _f F _g
In the general formula (1-1), a, b, c, d, e1, e2, f, g are 0.5 ≦ a ≦ 2, 0.5 ≦ b ≦ 0.97, 0 <c <0. 5, 0 <d <0.5, 0 <e1 ≦ 0.2, 0 ≦ e2 <0.2, 0 <e1 + e2 ≦ 0.2, b + c + d + e1 + e2 = 1, 1.8 ≦ f ≦ 2.2, 0 < Satisfy g ≦ 0.2.
D ¹ Is Zr.
D ² Is Li, Ni, Co, Mo, D ¹ , O, and elements other than F. The production method according to claim 6 or 7, wherein the firing step includes a step of heating at at least 775 ° C. for 10 hours. A step of producing a lithium nickel cobalt molybdenum oxide by the method according to any one of claims 6 to 8 .
A method for manufacturing a lithium ion secondary battery, comprising a step of manufacturing a positive electrode using the lithium nickel cobalt molybdenum oxide.

Images