JP2003017054A - Positive electrode active material, and manufacturing method of non-aqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate influence of lithium carbonate and lithium sulfate in the positive electrode active material. SOLUTION: The lithium compound oxide expressed in a general formula Lix Niy M1-y O2 (M means at least one kind of transient metal among B, Al, Co, Cr, Ga, In, and 0.05<=x<=1.10, 0.7<=y<=1.0) is washed with the water at a rate of at least 500 ml to the lithium compound oxide of 100g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode active material in which lithium carbonate and lithium sulfate are removed to improve charge / discharge efficiency and a method for manufacturing a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, due to advances in electronic technology, electronic devices have been improved in performance, downsized, and made portable, and there has been an increasing demand for high energy density batteries used in these electronic devices. Under such circumstances, LiCoO 2
A lithium-ion secondary battery using ₂ as a positive electrode material and a carbon material capable of doping and dedoping lithium as a negative electrode material has been commercialized, and is a power source for various portable electronic devices such as camcorders, mobile phones, and laptop computers. Has been adopted as.

Recently, this lithium ion secondary battery is often used not only in a room temperature environment but also in electronic equipment used in various environments from low temperature to high temperature. In particular, in laptop computers that have been increasingly adopted recently, the internal temperature of the computer rises with the speeding up of the central processing unit, and the built-in lithium ion secondary battery is used for a long time in a high temperature environment. Battery characteristics under high temperature environment are important.

On the other hand, the raw material for this lithium ion secondary battery
LiCoO for stable supply of materials _TwoInstead of
General formula Li mainly_xNi_yM_1-yO_Two(However
Where M is a transition metal, B, Al, Co, Cr, Ga, In
Of at least one of 0.05 ≦ x ≦ 1.10.
And 0.7 ≦ y ≦ 1.0. ) Represented by
There is a need for a method of using a composite oxide of um as a positive electrode active material.
Has been.

[0005]

However, the above L
_{i x Ni y M 1-y} O 2 is the charge-discharge capacity due to the effect of substitution with M becomes substantially smaller, the more, especially if M contains Al, against charge capacity significantly Initial The discharge capacity ratio (first charge / discharge efficiency) becomes very low. Further, since lithium carbonate and lithium sulfate are produced after the synthesis, these compounds are oxidatively decomposed to generate gas when placed in a charged state and in a high temperature environment.

This is not a problem when using a metal-made exterior as in conventional batteries, but when using an aluminum laminate or the like for the exterior as in polymer batteries. However, the battery exterior greatly swells due to the generation of a slight amount of gas, which is a very severe condition. That is, when an aluminum laminate material or the like is used for the exterior, this slight amount of gas generation causes dimensional defects or marked deterioration of battery performance. And this is Li _x in the polymer battery.
This is the biggest problem that prevents the practical use of Ni _y M _1-y O ₂ .

Therefore, Japanese Patent Laid-Open No. 6-342657 discloses a method in which lithium carbonate in the synthesized lithium composite oxide is removed by washing with minimal water and drying to avoid adverse effects. . However, in the positive electrode active material produced based on the example of JP-A-6-342657, the exchange rate of H ⁺ and Li ^{+ in} the solid is not taken into consideration, and Li _{x- z} H
_{z Ni 2-x-y M} y O 2 is may cause the generated charge and discharge capacity degradation, also, in order to perform washing with minimal water, the higher the Li ⁺ ion concentration in the water, the water after drying Lithium oxide and lithium carbonate may re-precipitate. In a cell using a soft material such as an aluminum laminate material, the gas generated from such a small amount of components cannot be ignored.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and a method for producing a positive electrode active material in which the effects of lithium carbonate and lithium sulfate formed in the positive electrode active material are eliminated, and a method for producing the same. An object of the present invention is to provide a method for producing a non-aqueous electrolyte battery having a high capacity and excellent storage characteristics under a high temperature environment by using such a positive electrode active material.

[0009]

The method for producing a positive electrode active material according to the present invention comprises a general formula Li _x Ni _y M _1-y O ₂ (where M
Represents at least one of transition metals, B, Al, Co, Cr, Ga, and In, and 0.05 ≦ x ≦ 1.10 and 0.7 ≦ y ≦ 1.0. ) The lithium composite oxide represented by (4) is washed with 500 ml or more of water per 100 g of the lithium composite oxide.

In the method for producing a positive electrode active material according to the present invention as described above, since the lithium composite oxide is washed with 500 ml or more of water per 100 g of the lithium composite oxide, the lithium composite oxide synthesis is performed. Lithium carbonate and lithium sulfate that are sometimes generated are sufficiently removed, and recrystallization of Li ions is also prevented.

The method for producing a non-aqueous electrolyte battery of the present invention comprises a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a non-aqueous electrolyte interposed between the positive electrode and the negative electrode. a method of manufacturing a nonaqueous electrolyte battery, when manufacturing the positive electrode active material, the general formula _{Li x Ni y M 1-y} O 2
(However, M is a transition metal, B, Al, Co, Cr, Ga,
Represents at least one of In and 0.05 ≦ x ≦ 1.
10 and 0.7 ≦ y ≦ 1.0. ) The lithium composite oxide represented by
It is characterized by being washed with 500 ml or more of water per g.

In the method of manufacturing a non-aqueous electrolyte battery according to the present invention as described above, when manufacturing the positive electrode active material, the lithium composite oxide is washed with 500 ml or more of water per 100 g of the lithium composite oxide. Therefore, lithium carbonate and lithium sulfate generated during the synthesis of the lithium composite oxide are sufficiently removed, and recrystallization of Li ions is also prevented. By using such a positive electrode active material, a charge / discharge efficiency is improved and a non-aqueous electrolyte battery in which gas generation in a high temperature environment is suppressed can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a positive electrode active material and a non-aqueous electrolyte battery to which the present invention is applied will be described with reference to the drawings.

This positive electrode active material has the general formula Li _x Ni _y M
_1-y O ₂ (however, M is a transition metal, B, Al, Co, C
represents at least one of r, Ga and In, and is 0.05
≦ x ≦ 1.10 and 0.7 ≦ y ≦ 1.0. )
The lithium composite oxide represented by is washed with water of 500 ml or more for 4 hours or less with respect to 100 g of the lithium composite oxide, and dried at a temperature of 200 ° C. or more.

Specifically, first, a lithium salt, a nickel salt, and an M salt (where M is a transition metal, B, Al, Co,
It represents at least one of Cr, Ga and In. ) Are mixed with each other, and the mixture is fired to obtain the general formula Li
A lithium composite oxide represented by _x Ni _y M _1-y O ₂ is obtained.

Next, the obtained lithium composite oxide is washed with water. By cleaning the lithium composite oxide,
Lithium carbonate and lithium sulfate produced during the synthesis of the lithium composite oxide are removed. The lithium carbonate and lithium sulfate are Li ⁺ during the charge and discharge reaction of the lithium composite oxide.
It is considered that the dope-dedoping reaction is inhibited.

In the present invention, in washing the lithium composite oxide, 500 ml or more of water is used per 100 g of the lithium composite oxide. Lithium composite oxide 10
Washing with less than 500 ml of water with respect to 0 g cannot sufficiently remove lithium carbonate or lithium sulfate generated during the synthesis of the lithium composite oxide, and the Li ion concentration in the wash water becomes high, so that the lithium composite oxide After drying, the Li ions are recrystallized as lithium hydroxide and lithium carbonate. When the positive electrode active material contains lithium hydroxide and lithium carbonate, when a battery is constructed, lithium hydroxide and lithium carbonate are oxidized and decomposed in a charged state, which causes gas generation. By washing with 500 ml or more of water per 100 g of the lithium composite oxide, lithium carbonate and lithium sulfate produced during the synthesis of the lithium composite oxide can be sufficiently removed, and Li
Recrystallization of ions can also be prevented.

The method for washing the lithium composite oxide is not particularly limited, and a method of washing with running water may be used, or alternatively, the lithium composite oxide may be washed by pouring the lithium composite oxide into stagnant water and stirring. You can also do
Further, in the cleaning, a method of cleaning with a large amount of water at a time may be used, or a method of cleaning a plurality of times with a small amount of water may be used. When washing multiple times, the total amount of water used is
The amount is 500 ml or more per 100 g of the positive electrode active material.

Next, the washed lithium composite oxide is dehydrated. The method of dehydration is not particularly limited, filtration, decantation, filter press, etc.
Various techniques can be used.

Here, in the present invention, a series of steps from washing to dehydration is performed within 4 hours. 4 steps of washing-dehydration
When the time is exceeded, the ion exchange between Li ⁺ and H ⁺ cannot be ignored, and the charge / discharge capacity of the positive electrode active material is significantly reduced. The exchange of H ⁺ and Li ⁺ proceeds depending on the time, not the amount of water used for washing. Therefore, by performing the series of steps from washing to dehydration within 4 hours, it is possible to substantially suppress ion exchange between Li ⁺ and H ⁺ , which adversely affects the charge and discharge capacity of the positive electrode active material.

Next, the dehydrated lithium ion composite oxide is dried in an air atmosphere at 200 ° C. or higher or in a thermostatic chamber in a vacuum atmosphere. If the drying temperature is 200 ° C. or lower, water adsorbed on the surface of the lithium composite oxide cannot be sufficiently removed. When water is adsorbed on the surface of the positive electrode active material, when the battery is constructed, this water is electrolyzed in a charged state and causes gas generation. By setting the drying temperature to 200 ° C. or higher, water adsorbed on the surface of the lithium composite oxide can be sufficiently removed. A Karl Fischer moisture meter is used to measure the end of drying at a measurement temperature of 25
The amount of residual water when measured as 0 ° C. is 800 ppm or less. By setting the residual water content to 800 ppm or less, generation of gas due to electrolysis of water adsorbed on the surface of the positive electrode active material can be neglected.

The drying method is not particularly limited, and spray drying, freeze drying, etc. may be used.
Various techniques can be used. Further, drying in a vacuum atmosphere is not always necessary, and it is possible to perform it in an atmosphere such as air.

As described above, the general formula Li _x Ni _y M
_1-y O ₂ (however, M is a transition metal, B, Al, Co, C
represents at least one of r, Ga and In, and is 0.05
≦ x ≦ 1.10 and 0.7 ≦ y ≦ 1.0. )
A positive electrode active material composed of a lithium composite oxide represented by is obtained.

According to the method for producing a positive electrode active material as described above, since 500 ml or more of water is washed with 100 g of the lithium composite oxide, lithium carbonate or lithium sulfate produced during the synthesis of the lithium composite oxide is not generated. It is removed by washing with water. In addition, H ⁺ and Li ⁺ generated during cleaning
The ion exchange proceeds depending on the time, not the amount of water used at the time of washing with water. Therefore, by performing washing with water in a short time of 4 hours or less as in the present invention, ion exchange hardly occurs.

A battery using this positive electrode active material is
The charge / discharge efficiency is greatly improved, and the discharge capacity is greatly increased. Furthermore, in a battery using this positive electrode active material,
No gas is generated in a high-temperature environment, the storage characteristics are excellent, and deterioration of battery performance in a high-temperature environment is suppressed.

Next, a non-aqueous electrolyte battery using the above positive electrode active material will be described.

As shown in FIG. 1, the non-aqueous electrolyte battery 1 includes a negative electrode 2, a negative electrode can 3 for accommodating the negative electrode 2, and a positive electrode 4.
A positive electrode can 5 accommodating the positive electrode 4, a separator 6 disposed between the positive electrode 4 and the negative electrode 2, and an insulating gasket 7. The negative electrode can 3 and the positive electrode can 5 are filled with a non-aqueous electrolyte solution. It will be done.

The negative electrode 2 is made of, for example, a metallic lithium foil which serves as a negative electrode active material. When a material capable of being doped with lithium and dedoped from lithium is used as the negative electrode active material, the negative electrode 2 has the negative electrode active material layer containing the negative electrode active material formed on the negative electrode current collector. As the negative electrode current collector, for example, copper, stainless steel, nickel or the like can be used,
The shape thereof is preferably a foil shape, or a mesh shape such as mesh or expanded metal. The thickness is 5
Those having a thickness of μm to 30 μm are preferably used.

The negative electrode active material may be any one that can be doped or dedoped with lithium metal or lithium,
A lithium alloy of lithium and aluminum, lead, indium, or the like, a carbon material capable of being doped or dedoped with lithium, or a polymer such as polyacetylene or polypyrrole is used. The carbon material is not particularly limited, but pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphite,
Glassy carbons, organic polymer compound fired bodies (phenol resin, furan resin, etc. fired at an appropriate temperature), carbon fibers, activated carbon and the like can be used.

Particularly, non-graphitizable carbons are preferably used because of their large charge / discharge capacity per weight and excellent cycle characteristics. Among these, the (002) plane spacing is 0.370 nm or more, and the true density is 1.70 g / cm ^3.
And less than 70 by differential thermal analysis in air flow
A carbonaceous material having no exothermic peak above 0 ° C. is used.

Examples of the material having such a property include a carbonaceous material obtained by carbonizing an organic material by a method such as firing, and as a starting material for carbonization, a furfuryl alcohol or a furfural homopolymer, Furan resins consisting of copolymers are preferred. In particular,
Furfural + phenol, furfuryl alcohol + dimethylol urea, furfuryl alcohol, furfuryl alcohol + formaldehyde, furfuryl alcohol +
A polymer composed of furfural or furfural + ketones is preferably used.

Alternatively, as a raw material, a hydrogen / carbon atomic ratio of 0.
A petroleum pitch of 6 to 0.8 is used, a functional group containing oxygen is introduced into this, and so-called oxygen crosslinking is performed to obtain an oxygen content of 10
A carbonaceous material obtained by firing after forming a precursor of about 20% by weight is also suitable. Further, a carbonaceous material having a large doping amount with respect to lithium by adding a phosphorus compound or a boron compound when carbonizing the furan resin, petroleum pitch or the like can be used.

The graphite material must have a true specific gravity of 2.10 g / cm ³ or more, and a material having a true specific gravity of 2.18 g / cm ³ or more is preferable in order to obtain a higher negative electrode mixture filling property. Used for. In order to obtain such a true specific gravity, it is necessary that the interplanar spacing obtained by the X-ray diffraction method is 0.335 nm or more and 0.34 nm or less.
More preferably, it is 35 nm or more and 0.337 nm or less. The crystal thickness in the c-axis direction is preferably 16.0 nm or more, and more preferably 24.0 nm or more.

As the binder contained in the negative electrode active material layer, a known resin material or the like usually used as a binder for the negative electrode active material layer of this type of non-aqueous electrolyte battery can be used.

The negative electrode can 3 accommodates the negative electrode 2 and serves as an external negative electrode of the non-aqueous electrolyte battery 1.

The positive electrode 4 is formed by forming a positive electrode active material layer containing a positive electrode active material on a positive electrode current collector. As the positive electrode current collector, for example, aluminum, stainless steel, nickel or the like can be used, and the shape thereof is preferably a foil shape, or a mesh shape such as mesh or expanded metal. A thickness of 10 μm to 50 μm is preferably used.

As described above, the positive electrode active material has the general formula L
i _x Ni _y M _1-y O ₂ (where M is a transition metal, B, A
1, at least one of Co, Cr, Ga, and In, and 0.05 ≦ x ≦ 1.10 and 0.7 ≦ y ≦ 1.
It is 0. ) The lithium composite oxide represented by (4) was washed with 500 ml or more of water for 100 g of the lithium composite oxide within 4 hours and dried at a temperature of 200 ° C. or more.

As the binder contained in the positive electrode active material layer, a known resin material or the like usually used as a binder for the positive electrode active material layer of this type of non-aqueous electrolyte battery can be used.

The positive electrode can 5 accommodates the positive electrode 4 and serves as an external positive electrode of the non-aqueous electrolyte battery 1.

The separator 6 is for separating the positive electrode 4 and the negative electrode 2 from each other, and a known material that is usually used as a separator for a non-aqueous electrolyte battery of this type can be used. Examples include non-woven fabrics and synthetic resin porous membranes. In particular, a synthetic resin porous membrane is preferably used,
Among them, the polyolefin-based microporous film has a thickness, strength,
It is preferably used in terms of film resistance and the like. Specific examples include a microporous membrane made of polyethylene or polypropylene, and a microporous membrane obtained by combining these. Further, the thickness of the separator needs to be as thin as possible in view of the relationship between lithium ion conductivity and energy density. Specifically, the thickness of the separator is preferably 50 μm or less.

The insulating gasket 7 is incorporated in and integrated with the negative electrode can 3. The insulating gasket 7 is for preventing leakage of the nonaqueous electrolytic solution filled in the negative electrode can 3 and the positive electrode can 5.

As the non-aqueous electrolyte, a solution prepared by dissolving an electrolyte in an aprotic non-aqueous solvent is used.

As the non-aqueous solvent, for example, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, sulfolane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 2-methyltetrahydrofuran, 3- Methyl 1,3-dioxolane, methyl propionate, methyl butyrate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate and the like can be used. Particularly, from the viewpoint of voltage stability, propylene carbonate,
It is preferable to use cyclic carbonates such as vinylene carbonate and chain carbonates such as dimethyl carbonate, diethyl carbonate and dipropyl carbonate. Moreover, such non-aqueous solvents may be used alone or in combination of two or more.

Further, as an electrolyte to be dissolved in a non-aqueous solvent
Is, for example, LiPF₆, LiClO_Four, LiAs
F₆, LiBF_Four, LiCF_ThreeSO_Three, LiN (CF_Three
SO_Two) _TwoLithium salts such as This
Among these lithium salts, LiPF₆, LiBF_FourTo
Preference is given to using.

Then, such a non-aqueous electrolyte battery 1 is manufactured, for example, as follows.

As the negative electrode 2, first, a negative electrode active material and a binder are dispersed in a solvent to prepare a slurry negative electrode mixture. Next, the obtained negative electrode mixture is uniformly applied onto the negative electrode current collector and dried to form a negative electrode active material layer, thereby forming the negative electrode 2
Is created. As the binder for the negative electrode mixture, a known binder can be used, and a known additive or the like can be added to the negative electrode mixture. Further, metallic lithium serving as the negative electrode active material can be used as it is as the negative electrode 2.

As the positive electrode 4, first, the general formula Li _x Ni is used.
_y M _1-y O ₂ (where M is a transition metal, B, Al, C
represents at least one of o, Cr, Ga and In,
0.05 ≦ x ≦ 1.10 and 0.7 ≦ y ≦ 1.0. ) The lithium composite oxide represented by the formula (1) is synthesized, 100 g of the lithium composite oxide is washed with 500 ml or more of water for 4 hours or less, and dried at a temperature of 200 ° C. or more to obtain a positive electrode active material. . In addition, as a guide for the end of drying, use a Karl Fischer moisture meter,
The residual water content is 8 when measured at a measurement temperature of 250 ° C.
Until it becomes less than 00 ppm.

Next, the obtained positive electrode active material and the binder are dispersed in a solvent to prepare a slurry positive electrode mixture. Next, the obtained positive electrode mixture is uniformly applied onto the positive electrode current collector and dried to form a positive electrode active material layer, whereby the positive electrode 4 is manufactured. As the binder of the positive electrode mixture, a known binder can be used, and a known additive or the like can be added to the positive electrode mixture.

The non-aqueous electrolytic solution is prepared by dissolving an electrolyte salt in a non-aqueous solvent.

Then, the negative electrode 2 is accommodated in the negative electrode can 3, the positive electrode 4 is accommodated in the positive electrode can 5, and the separator 6 made of a polypropylene porous film or the like is disposed between the negative electrode 2 and the positive electrode 4. The nonaqueous electrolytic solution battery 1 is completed by injecting the nonaqueous electrolytic solution into the negative electrode can 3 and the positive electrode can 5, and caulking and fixing the negative electrode can 3 and the positive electrode can 5 via the insulating gasket 7.

In the production of the non-aqueous electrolyte battery 1 as described above, since 500 ml or more of water is washed with 100 g of the lithium composite oxide when producing the positive electrode active material, the lithium composite oxide is obtained. Lithium carbonate and lithium sulfate produced during the synthesis are removed by washing with water. Also,
Since the exchange of H ⁺ and Li ⁺ generated during washing proceeds depending on the time, not the amount of water used during washing, it is possible to perform washing in a short time of 4 hours or less as in the present invention. , Ion exchange hardly occurs.

The non-aqueous electrolyte battery 1 obtained by using such a positive electrode active material has significantly improved charge / discharge efficiency and greatly increased discharge capacity. Further, the non-aqueous electrolyte battery 1 is excellent in that no gas is generated in a high temperature environment, storage characteristics are excellent, and deterioration of battery performance in a high temperature environment is suppressed.

In the above-mentioned embodiment, the non-aqueous electrolyte battery using the non-aqueous electrolyte was described as an example, but the present invention is not limited to this, and the conductive polymer compound is used. It is also applicable to a solid electrolyte battery using a polymer solid electrolyte containing a single substance or a mixture thereof, and a gel electrolyte battery using a gel solid electrolyte containing a swelling solvent.

Specific examples of the conductive polymer compound contained in the above-mentioned polymer solid electrolyte or gel electrolyte include silicon, acrylic, acrylonitrile, polyphosphazene modified polymer, polyethylene oxide, polypropylene oxide, fluorine-based polymer or Examples thereof include composite polymers, crosslinked polymers and modified polymers of these compounds. Examples of the fluorine-based polymer include poly (vinylidene fluoride), poly (vinylidene fluoride-co-hexafluoropropylene), poly (vinylidene fluoride-co-tetrafluoroethylene), and poly (vinylidene fluoride-co-trifluorethylene). ) And the like.

Further, in the above-mentioned embodiment, the secondary battery is described as an example, but the present invention is not limited to this, and can be applied to a primary battery. Further, the battery of the present invention is not particularly limited in its shape such as a cylindrical type, a square type, a coin type, a button type,
Further, it can be formed in various sizes such as thin and large.

[0056]

EXAMPLES Examples will be described below for confirming the effects of the present invention. In the following description, specific examples such as numerical values are described, but it goes without saying that the present invention is not limited to this.

<Sample 1> First, a positive electrode was prepared as follows. Li: Ni: Co = 1.01: 0.8 in molar ratio of lithium hydroxide, nickel oxide, and cobalt oxide.
The mixture was mixed with a ball mill so that the ratio became 0: 0.20. This mixture was calcined in 100% oxygen at 450 ° C. for 5 hours and then further calcined at 750 ° C. for 10 hours to obtain a lithium composite oxide. After the firing was completed, the lithium composite oxide was crushed.

Then, 100 g of lithium composite oxide and 500 ml of distilled water were placed in a 1000 ml beaker, stirred with a stirrer for 10 minutes, transferred to a suction filter and dehydrated in 5 minutes. The time required for washing with water is 0.25 as the time from the addition of distilled water to the beaker until the end of suction filtration.
It took time. Next, the positive electrode active material remaining on the filter paper was quickly placed in a constant temperature bath maintained at 200 ° C., preliminarily dried for 0.5 hours, and then the high temperature chamber was evacuated to dry for 4 hours to obtain the positive electrode active material. Got The residual water content of this positive electrode active material was measured at a measurement temperature of 250 using a Karl Fischer moisture meter.
When measured as ° C, the residual water content was 700 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was produced. First, 91% by weight of this positive electrode active material and 6% by weight of graphite as a conductive agent.
And 3% by weight of polyvinylidene fluoride as a binder were mixed to prepare a positive electrode mixture, which was dispersed in N-methyl-2pyrrolidone to obtain a positive electrode mixture slurry. Then, the dried slurry was pulverized to obtain a positive electrode mixture.

Then, this positive electrode mixture was pressure-molded together with an aluminum mesh and punched into a circular shape having a diameter of 15.5 mm to obtain a positive electrode pellet. Further, a negative electrode pellet was prepared by punching out a lithium metal foil into a circular shape having a diameter of 15.5 mm.

Then, the negative electrode pellets were placed in a negative electrode can,
The positive electrode pellet was housed in a positive electrode can, and a separator made of a polypropylene porous film or the like was placed between the negative electrode pellet and the positive electrode pellet. A nonaqueous electrolytic solution battery was completed by injecting a nonaqueous electrolytic solution into the negative electrode can and the positive electrode can, and caulking and fixing the negative electrode can and the positive electrode can through an insulating gasket. The non-aqueous electrolyte was prepared by dissolving LiPF _{6 in} propylene carbonate at 1 mol / L.

<Sample 2> The amount of water used for washing the lithium composite oxide was 2 with respect to 100 g of the lithium composite oxide.
It was adjusted to 50 ml and stirred for 2 minutes with a stirrer. Then, after waiting 3 minutes for the precipitation of the lithium composite oxide, the supernatant was drained by decantation, 250 ml of distilled water was added again, the mixture was stirred for 5 minutes with a stirrer, transferred to a suction filter, and dehydrated in 5 minutes. . Therefore, the amount of distilled water used and the time required for washing with water are the same as those of Sample 1, which are 500 ml and 0.25 hours, respectively. After that, the positive electrode active material was obtained by drying in the same manner as in Sample 1. The residual water content of this positive electrode active material was 700 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 3> The amount of water used for cleaning the lithium composite oxide was 1 with respect to 100 g of the lithium composite oxide.
A positive electrode active material was obtained in the same manner as in Sample 1 except that the amount was 000 ml. The residual water content of this positive electrode active material is 80
It was 0 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 4> The lithium composite oxide was fired in the same manner as in sample 1, and after the firing, the lithium composite oxide was pulverized. Then, without washing with water, pre-drying at 200 ° C. in air is performed for 0.5 hours in the same manner as in Sample 1 below, and then the atmosphere is vacuumed for 4 hours to dry.
A positive electrode active material was obtained. The positive electrode active material has a residual water content of 70.
It was 0 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 5> The amount of water used for washing the lithium composite oxide was 3 with respect to 100 g of the lithium composite oxide.
A positive electrode active material was obtained in the same manner as in Sample 1 except that the amount was set to 00 ml. The residual water content of this positive electrode active material is 800
It was ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 6> The amount of water used for washing the lithium composite oxide was 1 with respect to 100 g of the lithium composite oxide.
It was adjusted to 50 ml and stirred for 2 minutes with a stirrer. Then, after waiting 3 minutes for the precipitation of the lithium composite oxide, the supernatant was drained by decantation, 150 ml of distilled water was added again, the mixture was stirred for 5 minutes with a stirrer, transferred to a suction filter, and dehydrated for 5 minutes. It was Therefore, the amount of distilled water used and the time required for washing with water are the same as those of Sample 5, which are 300 ml and 0.25 hours, respectively. Thereafter, it was dried in the same manner as in Sample 1 to obtain a positive electrode active material. The positive electrode active material had a residual water content of 800 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 7> The amount of water used for washing the lithium composite oxide was 1 with respect to 100 g of the lithium composite oxide.
Rinsing with water was performed in the same manner as in Sample 1 except that the amount was 000 ml and the washing time was 0.5 hours. Then, the positive electrode active material remaining on the filter paper was quickly placed in a constant temperature bath maintained at 200 ° C., pre-dried for 0.5 hours, and then the interior of the constant temperature bath was evacuated for 1.5 hours to dry the positive electrode. An active material was obtained. The residual water content of this positive electrode active material was 1500 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 8> The amount of water used for washing the lithium composite oxide was 1 with respect to 100 g of the lithium composite oxide.
Rinsing with water was performed in the same manner as in Sample 1 except that the amount was 000 ml and the washing time was 0.5 hours. Then, the lithium composite oxide remaining on the filter paper was quickly put in a constant temperature bath kept at 200 ° C., pre-dried for 0.5 hours, and then the interior of the constant temperature bath was evacuated for 4 hours to dry the positive electrode. The substance was obtained. The residual water content of this positive electrode active material is 800 ppm
Met.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 9> The amount of water used for washing the lithium composite oxide was 1 with respect to 100 g of the lithium composite oxide.
Rinsing with water was performed in the same manner as in Sample 1 except that the amount was 000 ml and the washing time was 0.5 hours. Then, the positive electrode active material remaining on the filter paper was quickly placed in a constant temperature bath kept at 200 ° C., pre-dried for 0.5 hours, and then the interior of the constant temperature bath was evacuated for 15 hours to dry the positive electrode active material. Got The residual water content of this positive electrode active material was 100 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 10> A positive electrode active material was obtained in the same manner as in Sample 1, except that the amount of water used for washing the lithium composite oxide was 1000 ml with respect to 100 g of the lithium composite oxide, and the washing time was 1 hour. It was The residual water content of this positive electrode active material was 700 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 11> A positive electrode active material was obtained in the same manner as in Sample 1, except that the amount of water used for washing the lithium composite oxide was 1000 ml with respect to 100 g of the lithium composite oxide, and the washing time was 4 hours. It was The positive electrode active material had a residual water content of 800 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 12> The lithium composite oxide was washed with water in the following procedure so that the washing time was 0.1 hour. First, the amount of water was set to 1000 ml per 100 g of the lithium composite oxide, and the mixture was stirred for 3 minutes with a stirrer. Then, after the precipitation of the lithium composite oxide is specified, the supernatant liquid is drained by decantation, and the state in which excess water is absorbed with cotton is considered to be washing, and the time up to this point is 0.1 hour. It was Thereafter, the positive electrode active material was obtained by drying in the same manner as in Sample 1. The positive electrode active material had a residual water content of 800 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 13> A positive electrode active material was obtained in the same manner as in Sample 1, except that the amount of water used for washing the lithium composite oxide was 1000 ml with respect to 100 g of the lithium composite oxide, and the washing time was 6 hours. It was The residual water content of this positive electrode active material was 700 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 14> A positive electrode active material was obtained in the same manner as in Sample 1, except that the amount of water used for washing the lithium composite oxide was 1000 ml with respect to 100 g of the lithium composite oxide, and the washing time was 12 hours. It was The residual water content of this positive electrode active material was 700 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 15> Washing with water was carried out in the same manner as in Sample 1, except that the amount of water used for washing the lithium composite oxide was 1000 ml with respect to 100 g of the lithium composite oxide, and the washing time was 0.5 hours. It was And
The lithium composite oxide remaining on the filter paper was quickly put in a constant temperature bath kept at 250 ° C., pre-dried for 0.5 hours, and then the interior of the constant temperature bath was evacuated for 4 hours to dry the positive electrode active material. Obtained. The residual water content of this positive electrode active material is 500 pp
It was m.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

<Sample 16> Washing with water was carried out in the same manner as in Sample 1, except that the amount of water used for washing the lithium composite oxide was 1000 ml with respect to 100 g of the lithium composite oxide, and the washing time was 0.5 hours. It was And
The lithium composite oxide remaining on the filter paper was quickly placed in a constant temperature bath kept at 150 ° C, pre-dried for 0.5 hours, and then the interior of the constant temperature bath was evacuated for 4 hours to dry the positive electrode active material. Obtained. The residual water content of this positive electrode active material is 2000 p
It was pm. Then, it was further dried in a vacuum for 12 hours to finally give a residual water content of 1500 ppm.

Then, using this positive electrode active material, a coin type non-aqueous electrolyte battery was prepared in the same manner as in Sample 1.

With respect to the non-aqueous electrolyte batteries prepared in Samples 1 to 16 as described above, the charge capacity and discharge capacity in the first cycle were measured, and the discharge capacity / charge capacity (%) was taken as the initial charge / discharge efficiency. did. After that, the battery was charged, the coin-type battery was disassembled, and then a swelling test was performed to evaluate the presence or absence of gas generation.

<Evaluation of Charge / Discharge Cycle> With respect to the batteries prepared in Samples 1 to 16, the following charge / discharge test was conducted with the battery temperature at room temperature.

First, a current density of 0.2 was set for each battery.
Constant current charging is performed at 7 mA / cm ² until the circuit voltage reaches 4.2 V, and then constant voltage charging is performed at a constant voltage of 4.2 V from the time when the circuit voltage reaches 4.2 V to full charge. It was Next, each battery after charging was discharged until the final voltage reached 2.5V. This charge / discharge was defined as one cycle, and the discharge capacity / charge capacity (%) of the first cycle was defined as the initial charge / discharge efficiency.

<Evaluation of Gas Generation> Then, each battery charged under the above charging conditions was disassembled so as not to short-circuit, and only the positive electrode pellet was taken out. This positive electrode pellet was vacuum sealed in an aluminum pack. The vacuum-sealed pack was allowed to stand in a thermostat kept at 90 ° C. for 4 hours, and the swelling of the pack due to gas generation was visually observed.

Table 1 shows the above evaluation results of the batteries prepared in Samples 1 to 16.

[0097]

[Table 1]

Further, the positive electrode active materials synthesized in Samples 1 to 16 were subjected to X-ray diffraction measurement. The X-ray diffraction charts of the positive electrode active materials obtained in Sample 1 and Sample 4 are shown in FIG. Further, an enlarged view of the 20 ° to 35 ° portion in FIG. 2 is shown in FIG.

Except for sample 4 which was not washed with water at all, there were no diffraction peaks of lithium carbonate and lithium sulfate,
A good match was found with the LiNiO ₂ described in ISDD card 09-0063. In Sample 4, peaks indicating the presence of lithium carbonate and lithium sulfate were
Although it was close to the noise level, it was slightly present.

From the result of X-ray diffraction measurement, it is clear that the amount of lithium carbonate and lithium sulfate decreased by washing with water. Then, as can be seen from the results shown in Table 1, it is found that the charge / discharge efficiency of Sample 4 is about 84.5% and that gas is generated.

As shown in Table 1, first, in Samples 1 to 3, Sample 5 and Sample 6, the washing time was 0.25 hours. In this case,
It can be seen that in Samples 1 to 3 in which the amount of water was 500 ml or more per 100 g of the lithium composite oxide, the charge / discharge efficiency was significantly improved and the discharge capacity was large. Also, no gas is generated. However, the amount of water is 30
The charge and discharge efficiency and discharge capacity of Sample 5 and Sample 6 of 0 ml are slightly improved as compared with Sample 4, but gas is generated, which is not preferable. It is considered that this is because the amount of water used for washing is small, so that the removal of lithium carbonate and lithium sulfate becomes insufficient.

Therefore, in the washing treatment of the lithium composite oxide with water, 50% per 100 g of the lithium composite oxide was used.
It has been found that the amount of water is preferably 0 ml or more.

In Samples 2 and 6, washing with water is carried out in two steps. In this case, even if the amount of water per washing is small, the total amount of water is the same by washing with water several times. It can be seen that the same effect as that obtained by washing once with a moderate amount is obtained.

Therefore, in the water washing treatment, it is possible to perform water washing a plurality of times with a small amount of water, but even in that case, the total amount of water should be 500 ml or more per 100 g of the lithium composite oxide. Considered preferable.

Next, in Samples 7 to 9, the amount of water used for washing was 10 per 100 g of the lithium composite oxide.
The residual water content of the positive electrode active material after drying was changed by changing the drying time to 00 ml, the washing time to 0.5 hours, the drying temperature to 200 ° C. In this case, the residual water content after drying is 800 p as in Sample 8.
When it is pm or less, the charge and discharge efficiency is significantly improved, the discharge capacity is large, and no gas is generated. Further, it can be seen that even if the residual water content is reduced to 100 ppm as in Sample 9, it is equivalent to 800 ppm. However, in the case of Sample 7 having a residual water content of 1500 ppm after drying, gas was generated. It is considered that this is because water was electrolyzed and gas was generated in the charged state due to the large amount of residual water.

Therefore, it was found that the residual water content after drying is preferably 800 ppm or less.

Next, in Sample 8 and Sample 10 to Sample 14, the amount of water was set to 1000 ml per 100 g of the lithium composite oxide, and the other conditions were almost the same except that the washing time was changed. In this case, it can be seen that in Sample 8, Sample 10, and Sample 11 in which the washing time was longer than 0.1 hour and 4 hours or less, the charging and discharging efficiency was significantly improved and the discharge capacity was large. Also, no gas is generated.

However, in sample 12 in which the washing time was 0.1 hour, the charge and discharge capacity and charge and discharge efficiency increased, but gas was generated. This is because when the water washing time was as short as 0.1 hour or less, the bubbles in the lithium composite oxide powder were not completely removed, so that the surface of the active material was not completely wetted and the dissolution of lithium carbonate or lithium sulfate was hindered. It is also considered that the gas was generated without completely removing lithium carbonate and lithium sulfate in the lithium composite oxide due to insufficient dissolution and diffusion of these impurities.

Further, Sample 1 in which the washing time was 6 hours
In 3, the charge and discharge capacity and charge and discharge efficiency started to decrease,
It can be seen that in Sample 14 in which the washing time is 12 hours, the charge / discharge capacity and charge / discharge efficiency are significantly reduced. this is,
When washing with water for more than 4 hours, lithium carbonate and lithium sulfate could be removed by washing with water, but the exchange of Li ⁺ and H ^{+ in} the lithium composite oxide crystals occurred to a non-negligible level, and the charge and discharge capacity and It is considered that the charging / discharging efficiency was lowered, and that the exchange amount of these ions was time-dependent.

That is, the exchange rate of Li ⁺ and H ⁺ is
Since it is slower than the dissolution rate of lithium carbonate or lithium sulfate, the exchange of Li ⁺ and H ⁺ can be neglected when the washing time is 4 hours or less, and therefore it is considered that the impurities lithium carbonate and lithium sulfate could be removed. . However, it is considered that when the water washing time exceeds 4 hours, the exchange of Li ⁺ and H ⁺ cannot be ignored, and the charge / discharge capacity and charge / discharge efficiency of the lithium composite oxide are significantly reduced.

Therefore, it was found that in the water washing treatment, the water washing time is preferably longer than 0.1 hour and 4 hours or less.

Next, in Samples 8, 15 and 16, washing with water was carried out under the same conditions and only the drying temperature was changed. In this case, from the results of Samples 8 and 15, the drying temperature was 200 ° C. It can be seen that, by the above, the charging / discharging efficiency is significantly improved and the discharging capacity is large. Also, no gas is generated.

However, in the case of Sample 16 which was dried at 150 ° C., although the charge and discharge efficiency and the discharge capacity were slightly improved, it was found that gas was generated, which is not preferable. It is considered that this is because the water adsorbed on the surface of the lithium composite oxide could not be sufficiently removed due to the low drying temperature, so that the water was electrolyzed in the charged state and gas was generated. Therefore, in order to suppress gas generation due to electrolysis of water adsorbed on the surface of the positive electrode active material,
It can be said that the residual water content needs to be 800 ppm or less. Moreover, since the amount of decrease of this water was small even when the drying time was extended by 12 hours as in Sample 16, it is estimated that it takes a very long time to reach 800 ppm or less at the temperature of 150 ° C. , Not practical.

Therefore, the drying after the water washing treatment is 200
It was found that it is preferable to carry out the treatment in an atmosphere at a temperature of not less than 0 ° C. and to set the residual water content to 800 ppm or less.

[0115]

In the present invention, when the positive electrode active material is manufactured, 500 ml or more of water is used for washing per 100 g of lithium composite oxide, so that lithium carbonate or lithium sulfate produced during the synthesis of lithium composite oxide is used. Are removed by washing with water. Further, since the exchange of H ⁺ and Li ⁺ generated during washing proceeds depending on the time, not the amount of water used during washing, the washing is performed in a short time of 4 hours or less as in the present invention. Therefore, ion exchange hardly occurs.

The non-aqueous electrolyte battery obtained by using such a positive electrode active material has significantly improved charge / discharge efficiency,
The discharge capacity is greatly increased. Furthermore, this non-aqueous electrolyte battery is excellent in that no gas is generated in a high temperature environment, the storage characteristics are excellent, and the deterioration of the battery performance in the high temperature environment is suppressed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a non-aqueous electrolyte battery manufactured by applying the present invention.

FIG. 2 is an X-ray diffraction chart of the positive electrode active materials obtained in Sample 1 and Sample 4.

FIG. 3 is an enlarged view of a portion of 20 ° to 35 ° in FIG.
It is a line diffraction chart.

[Explanation of symbols]

1 non-aqueous electrolyte battery, 2 negative electrode, 3 negative electrode can, 4
Positive electrode, 5 positive electrode can, 6 separator, 7 insulating gasket

Continued front page    F-term (reference) 4G048 AA04 AB02 AB05 AC06 AE05                 5H029 AJ03 AJ04 AJ14 AK03 AL06                       AL12 AL16 AM03 AM04 AM05                       AM07 AM16 CJ02 CJ12 CJ28                       HJ00 HJ01 HJ02 HJ14                 5H050 AA08 AA09 AA19 BA15 CA08                       CB07 CB12 CB20 DA02 GA02                       GA12 GA27 HA00 HA01 HA02                       HA14 HA20

Claims (6)

[Claims] 1. A general formula Li _x Ni _y M _1-y O ₂ (where M is a transition metal, B, Al, Co, Cr, Ga, In).
Of at least one of 0.05 ≦ x ≦ 1.10.
And 0.7 ≦ y ≦ 1.0. The method for producing a positive electrode active material, comprising rinsing the lithium composite oxide represented by (4) with 500 ml or more of water per 100 g of the lithium composite oxide. 2. The method for producing a positive electrode active material according to claim 1, wherein the washing time with water is within 4 hours. 3. 200 ° C. after washing the lithium composite oxide with water
The method for producing a positive electrode active material according to claim 1, wherein the final amount of water contained in the lithium composite oxide is 800 ppm or less by drying at the above temperature. 4. A method for manufacturing a non-aqueous electrolyte battery comprising a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a non-aqueous electrolyte interposed between the positive electrode and the negative electrode. In producing the substance, the general formula Li _x Ni _y M _1-y O ₂ (wherein M represents at least one of transition metals, B, Al, Co, Cr, Ga and In, and 0.05 ≦ x ≦ 1.10 and 0.7
≦ y ≦ 1.0. ) 500 ml of the lithium composite oxide represented by
A method for manufacturing a non-aqueous electrolyte battery, which comprises washing with water as described above. 5. The method for producing a non-aqueous electrolyte battery according to claim 4, wherein the washing time is within 4 hours. 6. 200 ° C. after washing the lithium composite oxide with water
The method for producing a non-aqueous electrolyte battery according to claim 4, wherein the final amount of water contained in the lithium composite oxide is 800 ppm or less by performing drying at the above temperature.