JPH06215800A - Lithium battery - Google Patents

Abstract

PURPOSE:To solve the existing problems such as insufficient charge and discharge capacity of a high voltage part and poor shelf life characteristic, and provide a lithium battery with large charge and discharge energy and excellent shelf life characteristic. CONSTITUTION:A lithium battery contains, as a positive electrode active material, a complex oxide represented by the composition formula: LiNi1-xM2O2 (M is an element capable of forming a positive ion other than Ni, Co which partially substitutes Ni of LiNiO2, 0<X<=0.5) in which the peak intensity of spacing 4.72+0.03 A to the peak intensity of spacing 2.03+0.02 A is 1.2 times or more. Thus, a small-sized lithium battery with large charge and discharge energy and good shelf life characteristic can be constituted, and utilized in various fields including a power source for various portable electronic equipments.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium battery, and more particularly to a lithium secondary battery which can be charged and discharged, and more particularly to a positive electrode active material which provides a battery having large charge and discharge energy and excellent storage characteristics. Is.

[0002]

2. Description of the Related Art Non-aqueous electrolyte batteries using an alkali metal such as lithium and its alloys as a negative electrode active material are
The large discharge capacity and the reversibility of charge are made compatible by the insertion or intercalation reaction of the negative electrode metal ion to the positive electrode active material. Conventionally, as a secondary battery using lithium as a negative electrode active material, a battery using a layered or tunnel oxide such as titanium disulfide or vanadium pentoxide as a positive electrode active material has been proposed. It was low, and the charge / discharge capacity, and thus the charge / discharge energy, was not sufficient.

As a method for overcoming the above drawbacks,
It has been proposed to use a compound containing lithium as a positive electrode active material, and electrochemically desorbs lithium during initial charging to simultaneously carry out an oxidation reaction of the positive electrode active material, resulting in a high voltage of around 4 V. This enables lithium batteries with excellent ionic conductivity. Examples of this are LiMn ₂ O ₄ (Patent Publication No. 58-34414, etc.) and LiCoO ₂ (Mizushima et al., Mat.Res.Bul).
l., 15 , 783 (1990)).

[0004]

All of the above 4V type positive electrode materials have a problem that the charge / discharge capacity of the high voltage part is insufficient. Li / Mn> 0.5 for LiMn ₂ O _4.
With the above charging, the voltage is 3V due to the yarn teller effect.
It is thought that it will fall below, and its 4V region is 15
Limited to 4 mAh / g (T. Ohzuku et al., J.
Electrochem. Soc., 137 , 769 (1990)). LiC
In oO ₂ , when a large amount of lithium is desorbed during charging for the purpose of increasing the capacity, a sufficient charge / discharge capacity cannot be obtained because the crystal structure is not maintained due to electrostatic repulsion of the oxygen layer. . Further, in the case of LiCoO ₂ , there is a drawback that the cobalt compound as a raw material is very expensive.

LiNiO ₂ is composed of LiMn ₂ O ₄ and Li
It has good capacity characteristics compared to CoO ₂ and is promising in that it can realize the largest energy density. But Li
Similar to CoO ₂ , the crystal structure is not retained when a large amount of lithium is desorbed by charging, so that it has poor storage characteristics and is difficult to put into practical use. Therefore, the substitution system LiNi _1-x Co _x O ₂ has also been studied, but it has a drawback that the storage characteristics are still not excellent.

[0006]

An object of the present invention is to provide a lithium battery having a large charging / discharging energy and excellent storage characteristics, which solves the present problems that the charge / discharge capacity of the high voltage part is insufficient and the storage characteristics are poor. The purpose is to do.

[0007]

In order to achieve the above object, in the lithium battery of the present invention, in the X-ray diffraction analysis, the interplanar spacing is 4.72 ± 0.03Å with respect to the peak intensity of the interplanar spacing of 2.03 ± 0.02Å. Of the composition formula LiNi _1-x M _x O ₂ (M is LiNiO ₂ Ni
An element that can be a cation other than Ni and Co that partially substitutes the element, a complex oxide given by 0 <X ≦ 0.5), especially a nickel salt so that Li / (Ni + M) ≧ 2 in atomic ratio. A composition formula Li obtained by mixing the M salt and the lithium salt, heating and baking the mixture, and then washing and removing excess lithium.
Ni _1-x M _x O ₂ (0 <X ≦ 0.5), wherein M is a group IIIA or IIIB element of the periodic table as a positive electrode active material, and lithium or Using the compound as a negative electrode active material, it is chemically stable to the positive electrode active material and the negative electrode active material, and lithium ions move to cause an electrochemical reaction with the positive electrode active material or the negative electrode active material. It is characterized in that the substance to be obtained is an electrolyte substance.

The present invention will be described in more detail.

As a result of an earnest search for a material for a high energy density lithium battery which has a large charge / discharge energy and excellent storage characteristics, the inventor has found that, as described above, the peak of the interplanar spacing of 2.03 ± 0.02Å in X-ray diffraction analysis. The composition formula LiNi _1-x M _x O ₂ (where M is Ni or Co other than Ni that partially replaces Ni of LiNiO ₂₎ has a peak intensity of 1.22 times or more relative to the intensity of 1.22 or more. An element that can be a cation, a complex oxide given by 0 <X ≦ 0.5, especially a nickel salt, a salt of M and a lithium salt are mixed so that Li / (Ni + M) ≧ 2 in atomic ratio. Composition formula LiN obtained by heating and firing and then removing excess lithium by washing
i _1-x M _x O ₂ (0 <X ≦ 0.5), wherein M is an element of Group IIIA or IIIB of the periodic table is used as a positive electrode active material, It was confirmed that a lithium battery having higher charge / discharge energy and better storage characteristics than a conventional lithium battery can be constructed, and the present invention was completed based on this recognition.

The reason why the lithium battery of the present invention has a larger capacity than the prior art is considered as follows.
First, LiNi _1-x M _x O ₂ (M is an element that can become a cation other than Ni and Co that partially replaces Ni in LiNiO ₂ , 0 <X ≦ 0.5) is a component that works as an active material. In order to fully express the capacity characteristics of LiNiO ₂ ,
It is necessary that M is selectively replaced with nickel to suppress the mixing of nickel and the element M on the surface where lithium ions are present, and to improve the lithium ion conductivity when used as an active material of a lithium battery. To do this, L
iNi _1-x M _x O ₂ X-ray diffraction analysis revealed a plane spacing of 2.03
Distance between peaks of ± 0.02Å 4.72 ±
The peak intensity of 0.03Å must be 1.2 times or more.

The reason why the storage characteristics are improved is considered to be that the structural stability in the state where a large amount of lithium is desorbed by charging is improved by the substitution of the element M. However, when M is Co, the storage characteristics are not improved. It is considered that this is because the battery using LiCoO ₂ as the positive electrode active material has poor storage characteristics, and therefore even if it partially contains LiCoO ₂ , it cannot contribute to the improvement of stability. Further, when M is an element of Group IIIA or Group IIIB of the periodic table, the LiMO ₂ component contained in the crystal is not oxidized by charging, and as a factor for always maintaining the stability of the positive electrode active material. Since it works, it is possible to realize particularly excellent storage characteristics.

As described above, the substitution element M is LiNiO ₂
An element that is solid-dissolved so as to maintain the crystal structure of and selectively replaces nickel is preferable. From this viewpoint, M needs to be an element that can be a cation, and it is preferable to use an element having an ionic radius and an ionic valence close to that of nickel. Specifically, aluminum, gallium, indium, manganese, chromium, vanadium,
One or more of iron, titanium, copper, zinc, scandium, indium, yttrium, lanthanoid, boron and the like can be mentioned. Particularly from the viewpoint of storage characteristics, Group IIIA and III
As the Group B element, one or more of scandium, yttrium, lanthanoid, boron, aluminum, indium and the like can be mentioned as promising substitution elements.

In order to maintain a sufficient discharge capacity based on the redox couple of nickel, the substitution amount X needs to be 0.5 or less.

Here, LiNi _1-x M _x O ₂ (0 <X ≦ 0.
In the case of synthesizing 5), if the atomic ratio Li / (Ni + M) <2 is mixed and calcined at a temperature of 700 ° C. or higher necessary for generation, the lithium salt is lost by sublimation. (Ni + M) decreases significantly from 1.0. In this case, there is a phenomenon in which nickel ions and ions of the substituting element M are mixed into the surface of the calcined product where lithium ions are present, and conduction of lithium ions is obstructed and lowered. Therefore, the lithium salt is prevented from disappearing, and LiNi
_{1-x M x O 2 (} 0 <X ≦ 0.5) atomic ratio in Li /
In order to bring (Ni + M) close to 1.0, it is preferable to mix and heat the nickel salt, the salt of the substituting element M and the lithium salt so that Li / (Ni + M) ≧ 2 in atomic ratio during synthesis. Is.

Further, LiNi _1-x M _x O ₂ (0 <X ≦ 0.
In the synthesis of 5), unreacted lithium that does not sublime and is in excess forms lithium salts such as lithium oxide, lithium carbonate, and lithium hydroxide, so the powder after firing is LiNi.
_{1-x M x O 2 (} 0 <X ≦ 0.5) and it has become a mixture thereof unreacted lithium _{salt, LiNi 1-x M x O} 2 This calcined powder high solubility of these lithium salts (0 <X ≦
By washing 0.5) with a solvent that does not decompose, only the excess lithium salt can be eluted and removed. If a battery is manufactured with unreacted lithium still present, it causes a decrease in capacity and a battery short circuit, and therefore a cleaning / removal work is required.

As the nickel salt, the salt of the substituting element M and the lithium salt, hydroxides, carbonates, sulfates, nitrates, halogen compounds and the like can be used. Firing temperature is 700
C. to 1000.degree. C., more preferably 700.degree. C. to 800.degree. C. to minimize loss of lithium salt.

The present invention has high industrial value not only in realizing a battery having a large charge and discharge energy but also in utilizing a large amount of inexpensive nickel instead of expensive cobalt.

To form a positive electrode using this positive electrode active material, a mixture of the above-mentioned double oxide powder and a binder powder such as polytetrafluoroethylene is pressure-molded on a support such as stainless steel, or A conductive powder such as acetylene black is mixed in order to impart conductivity to the mixture powder, and a binder powder such as polytetrafluoroethylene is further added to the mixed powder as required, and the mixture is placed in a metal container. Alternatively, it is formed by means such as press-molding the above-mentioned mixture on a support such as stainless steel, or applying the above-mentioned mixture into a slurry form on a metal substrate.

Lithium, which is the negative electrode active material, is formed in the form of a sheet as in the case of a general lithium battery, or the sheet is pressure-bonded to a conductor network of nickel, stainless steel or the like to form a negative electrode. As the negative electrode active material, a lithium alloy such as a lithium-aluminum alloy can be used in addition to lithium. Further, a so-called negative electrode for a rocking chair battery such as carbon can be used. In the case of the present invention, a lithium ion supplied from the positive electrode by a charging reaction can be doped to form a carbon-lithium negative electrode.

As the electrolyte, for example, LiAsF ₆ , an organic solvent such as dimethoxyethane, 2-methyltetrahydrofuran, ethylene carbonate, methyl formate, dimethyl sulfoxide, propylene carbonate, acetonitrile, butyrolactone, dimethyl formamide, dimethyl carbonate or diethyl carbonate, L
A non-aqueous electrolyte solvent in which a Lewis acid such as iBF ₄ , LiPF ₆ , LiAlCl ₄ , or LiClO ₄ is dissolved, or a solid electrolyte can be used.

Furthermore, various other conventionally known materials can be used for other elements such as a separator and structural materials (battery case, etc.), and there is no particular limitation.

[0022]

EXAMPLES The method of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In addition, in the examples, the production and measurement of the battery were performed in a dry box under an argon atmosphere.

[0023]

EXAMPLE 1 FIG. 1 is a cross-sectional view of a coin battery, which is a specific example of the battery according to the present invention, in which 1 is a sealing plate, 2 is a gasket, 3 is a positive electrode case, 4 is a negative electrode, 5 is a separator,
6 shows a positive electrode material mixture pellet.

The positive electrode active material includes LiOH.H ₂ O and Ni.
_{(NO 3) 2 · 6H 2} O and _{Al (NO 3) 3 · 9H} 2 O 2
LiNi _0.8 Al _0.2 O ₂ obtained by mixing powders at a molar ratio of 0: 4: 1 and firing at 700 ° C. for 12 hours and vacuum-drying the powder at 100 ° C. was used. This sample is designated as A-1. When the X-ray diffraction characteristic diagram of the sample A-1 was measured using copper Kα ray, the characteristic diagram as shown in Fig. 2 was obtained, and the Joint Committee of Power Deflections Standard (Joint committee of powder diffra
ction standards) 9-63 registered LiNiO ₂
It is similar to the X-ray diffraction characteristic diagram of No. 1 and has the same structure. The size of the hexagonal unit cell calculated from this X-ray diffraction characteristic chart is shown in the table. Also, the interplanar spacing for the peak intensity of interplanar spacing 2.03 ± 0.02Å is 4.
The peak intensity of 72 ± 0.03Å is shown in the table as the R value.

The powder of the obtained sample A-1 was mixed with a conductive agent (acetylene black powder) and a binder (polytetrafluoroethylene), and the mixture was roll-molded to form a positive electrode mixture pellet 6 (thickness: 0.5 mm). , Diameter 15 mm). First, a metallic lithium negative electrode 4 is placed on a stainless steel sealing plate 1.
Was placed under pressure into the polypropylene gasket 2, and a polypropylene microporous separator 5 and a positive electrode material mixture pellet 6 were placed in this order on the negative electrode 4, and propylene carbonate was added as an electrolytic solution. LiClO ₄ was dissolved in an equal volume mixed solvent of dimethoxyethane 1
After injecting and impregnating an appropriate amount of the specified solution, the positive electrode case 3 made of stainless steel is covered and caulked to have a thickness of 2 m.
A coin-type battery having a diameter of m and a diameter of 23 mm was produced.

The battery using the sample A-1 thus synthesized as a positive electrode active material was charged to 4.5 V at a current density of 0.5 mA / cm ² and then discharged to 3.0 V. The discharge characteristics are shown in the table. It has a merit that it can discharge a large capacity at high voltage and can be used as a high energy density battery.

In addition, this battery was subjected to a voltage regulation charge / discharge of 3.0 V to 4.5 V at a charge / discharge current density of 0.5 mA / cm ² , respectively, and the capacity retention rate at the 10th cycle (= the discharge capacity at the 10th cycle). / (First discharge capacity) is shown in the table. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0028]

Examples 2 to 16 In Examples 2 to 16, lithium batteries prepared in the same manner as in Example 1 were used, except that Samples A2 to A16 synthesized as follows were used as the positive electrode active materials. The charge / discharge characteristics were examined.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O and 10: 4: 1 molar ratio, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.8 Al _0.2 O ₂ . This sample is A
-2.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O 50: 4: 1 molar ratio, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.8 Al _0.2 O ₂ . This sample is A
-3.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O 40: 7: were mixed in a molar ratio of 3, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.7 Al _0.3 O ₂ . This sample is A
-4.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O 8: 1: 1 molar ratio, after was 12 hours firing at 700 ° C., fired product 1
LiNi _0.5 Al _0.5 O ₂ was obtained by washing the powder with 50 parts by weight of water for 4 hours, and separating the filtrate by filtration to obtain a powder, which was vacuum dried at 100 ° C. This sample is A-
Set to 5.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Ga (NO 3) 3 · 9H} 2 O and 20: 4: 1 molar ratio, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight LiNi _0.8 Ga _0.2 O ₂ was obtained by vacuum-drying the powder obtained by washing and filtering the filtrate by filtration. This sample is A
-6.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
Mixing 6H ₂ O and B ₂ O ₃ in a molar ratio of 40: 8: 1,
After firing at 700 ° C. for 12 hours, 1 weight of the fired product was washed with 50 weight of water for 4 hours, the filtrate was separated by filtration, and the obtained powder was vacuum dried at 100 ° C. to obtain LiNi.
_0.8 B _0.2 O ₂ was obtained. This sample is designated as A-7.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ 6H ₂ O and Sc ₂ O ₃ were mixed in a molar ratio of 40: 8: 1, and calcined at 700 ° C. for 12 hours, then washed with 50 weight of water for 4 hours per 1 weight of calcined product, and filtered by filtration. The powder obtained by separating the liquid was vacuum dried at 100 ° C. to obtain L
iNi _0.8 Al _0.2 O ₂ was obtained. This sample is designated as A-8.

Next, LiOH.H ₂ O and Ni (NO ₃ ) 2
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O and 40: 9: 1 molar ratio, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.9 Al _0.1 O ₂ . This sample is A
-9.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Ga (NO 3) 3 · 9H} 2 O and 40: 9: 1 molar ratio, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.9 Ga _0.1 O ₂ . This sample is A
-10.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and B ₂ O ₃ were mixed in a molar ratio of 80: 18: 1, and calcined at 700 ° C. for 12 hours, then washed with 50 parts by weight of water for 4 hours and filtered by filtration. The powder obtained by separating the liquid was vacuum dried at 100 ° C. to obtain L
iNi _0.9 B _0.1 O ₂ was obtained. This sample is designated as A-11.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ 6H ₂ O and Sc ₂ O ₃ were mixed at a molar ratio of 80: 18: 1, and calcined at 700 ° C. for 12 hours, then washed with 50 weight of water for 4 hours per 1 weight of calcined product, and filtered by filtration. The powder obtained by separating the liquid was vacuum dried at 100 ° C. to obtain L
iNi _0.9 Al _0.1 O ₂ was obtained. This sample is designated as A-12.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Fe (NO 3) 3 · 9H} 2 O and 40: 9: 1 molar ratio, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.9 Fe _0.1 O ₂ . This sample is A
-13.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and the MnO 40: 9: 1 molar ratio,
After firing at 700 ° C. for 12 hours, 1 weight of the fired product was washed with 50 weight of water for 4 hours, the filtrate was separated by filtration, and the obtained powder was vacuum dried at 100 ° C. to obtain LiNi.
_0.9 Mn _0.1 O ₂ was obtained. This sample is designated as A-14.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Cr (NO 3) 3 · 9H} 2 O and 40: 9: 1 molar ratio, after was 12 hours firing at 700 ° C., baked product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.9 Cr _0.1 O ₂ . This sample is A
-15.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
Mixing 6H ₂ O and TiO ₂ in a molar ratio of 40: 9: 1,
After firing at 700 ° C. for 12 hours, 1 weight of the fired product was washed with 50 weight of water for 4 hours, the filtrate was separated by filtration, and the obtained powder was vacuum dried at 100 ° C. to obtain LiNi.
_0.9 Ti _0.1 O ₂ was obtained. This sample is designated as A-16.

When the X-ray diffraction characteristics of the samples A-2 to A-16 using copper Kα rays were measured, they were joint committee of power deflections standard (Joint committee of powder diffraction).
It is similar to the X-ray diffraction characteristic diagram of LiNiO ₂ registered in 9-63 of the standards), and it can be seen that it has the same structure. The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic chart is shown in the table. Also, the surface spacing is 2.03 ±
The interplanar spacing for the peak intensity of 0.02Å 4.72 ± 0.
The peak intensity of 03Å is shown as R value in the table. Also A-9
FIG. 3 shows the X-ray diffraction characteristic chart of

Samples A-2 to A- synthesized in this way
The table shows the charge / discharge characteristics when a battery using 16 as the positive electrode active material was charged to 4.5 V at a current density of 0.5 mA / cm ² and then discharged to 3.0 V. Both of them can discharge a large capacity at a high voltage and have an advantage that they can be used as a high energy density battery.

Further, these batteries were treated with 0.5 mA / cm ²
Table 10 shows the 10th capacity retention ratio (= 10th discharge capacity / 1st discharge capacity) when the voltage-regulated charge / discharge of 3.0V-4.5V was performed at the respective charge / discharge current densities. As is clear from the above, it can be seen that the capacity decrease due to the cycle is small in all cases.

In Examples 1 to 16, LiNi _{1 -x} M _x O ₂ (0 <X ≦ is different in the kind of the substitution element M and the substitution ratio.
0.5) was shown for the charge and discharge characteristics of the battery produced by using the positive electrode active material, but the type and substitution ratio of the substitution element M are not limited, and the interplanar spacing 2 is determined by X-ray diffraction analysis. The composition formula LiNi _1-x M _x O ₂ (M is N of LiNiO ₂₎ in which the peak intensity of 4.72 ± 0.03Å is 1.2 times or more the peak intensity of 0.03 ± 0.02Å
Elements that can be cations other than Ni and Co that partially substitute i, 0 <X ≦ 0.5, especially Li / (N in atomic ratio
i + M) ≧ 2, a nickel salt, a salt of an element M that can become a cation, and a lithium salt are mixed, heated and baked, and excess lithium is removed by washing to obtain a composition formula Li.
It goes without saying that similar effects are produced when the composite oxide given by Ni _1-x M _x O ₂ (0 <X ≦ 0.5) is used as the positive electrode active material.

[0048]

Example 17 A coin battery using Samples A-1 to A-16 as a positive electrode active material was newly prepared in the same manner as in Examples 1 to 16 and a storage characteristic test was conducted as follows. First, these batteries were cycle-charged and discharged 10 times in a voltage regulation range of 3.0V-4.5V at a current density of 0.5 mA / cm ² at 25 ° C., the discharge capacity at the 10th time was measured, and then charged. After reaching 0.5 V, the battery was charged at a constant voltage for 1 hour while keeping it at 4.5 V to make it overcharged. Then these batteries at 60 ° C for 1 hour
It was stored for a month, discharged again at 25 ° C. for the 11th time, the discharge capacity was measured, and the capacity retention ratio after storage = (11th discharge capacity) / (10th capacity) was examined. The results are shown in the table. As is clear from this, it is understood that the batteries of Samples A-1 to A-16 have good storage characteristics. Also M
It can be seen that when is a group IIIA or IIIB element of the periodic table, it has particularly good conservation.

In Example 17, LiNi _1-x M _x O ₂ (0 <X ≦ 0.
5) shows the storage characteristics of the battery prepared by using the positive electrode active material, but it is not limited to the kind of the substitution element M and the substitution ratio, and the interplanar spacing of 2.03 ± The compositional formula LiNi _1-x M _x O ₂ (M is a partial replacement of Ni in LiNiO ₂₎ in which the peak intensity of 0.02 Å is 1.2 times or more the peak intensity of 4.72 ± 0.03 Å Elements other than Ni and Co that can be cations, 0 <X ≦ 0.5, especially Li / (Ni +) in atomic ratio
M) ≧ 2, a composition formula LiNi obtained by mixing a nickel salt, a salt of an element M that can be a cation, and a lithium salt, heating and firing the mixture, and then washing and removing excess lithium.
_{In the} case of using a complex oxide, which is given by _1-x M _x O ₂ (0 <X ≦ 0.5) and in which M is an element of Group IIIA or IIIB of the periodic table, as a positive electrode active material, It goes without saying that the same effect will occur.

[0050]

Comparative Examples 1 to 12 In Comparative Examples 1 to 12, lithium batteries prepared in the same manner as in Example 1 were used, except that Samples B1 to B12 synthesized as follows were used as the positive electrode active materials. The charge / discharge characteristics and storage characteristics were examined.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ Mix 6H ₂ O at a molar ratio of 1: 1 and mix at 12
After firing for 4 hours, 50 wt.
After washing for 10 hours, the filtrate is separated by filtration to obtain 10
LiNiO ₂ was obtained by vacuum drying at 0 ° C.
This sample is designated as B-1. Sample B-1 using copper Kα ray
The X-ray diffraction characteristics of the joint were measured and found to be the Joint committee of powder diffraction standard.
s), which matches the pattern registered in 9-63, and B-1
Was identified as LiNiO ₂ . The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic chart is shown in the table. Further, the peak intensity of the interplanar spacing of 4.72 ± 0.03Å against the peak intensity of the interplanar spacing of 2.03 ± 0.02Å is shown in the table as an R value.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ 6H ₂ O was mixed at a molar ratio of 4: 1 and the mixture was heated at 700 ° C. for 12 hours.
After firing for 1 hour, 1 weight of the fired product was washed with 50 weight of water for 4 hours, and the filtrate was separated by filtration to obtain 100 powder.
LiNiO ₂ was obtained by vacuum drying at ℃. This sample is designated as B-2. When the X-ray diffraction characteristic diagram of Sample B-2 was measured using copper Kα rays, the Joint Committee of powder diffraction standard (Joint committee of powder diffraction standard)
s) the pattern registered in 9-63, and B-2
Was identified as LiNiO ₂ . The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic chart is shown in the table. Further, the peak intensity of the interplanar spacing of 4.72 ± 0.03Å against the peak intensity of the interplanar spacing of 2.03 ± 0.02Å is shown in the table as an R value.

Next, Li ₂ CO ₃ and CoCO ₃ were mixed at a molar ratio of 1: 2 and then calcined at 900 ° C. for 1 day to obtain a black powder. This sample is designated as B-3. When the X-ray diffraction diagram of Sample B-1 was measured using copper Kα rays, the Joint Committee of Power Deflections Standard (Joint committee of
B-3 was identified as LiCoO ₂ in agreement with the pattern registered in 16-427 of powder diffraction standards). The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic chart is shown in the table. Also, the surface spacing is 2.03 ±
The interplanar spacing for the peak intensity of 0.04Å 4.72 ± 0.
The peak intensity of 05Å is shown in the table as an R value.

Next, Li ₂ CO ₃ and CoCO ₃ were mixed at a molar ratio of 2: 1 and then calcined at 900 ° C. for 1 day to obtain a black powder. This sample is designated as B-4. When the X-ray diffraction characteristic diagram of Sample B-1 was measured using copper Kα rays, the Joint Committee of Power Deflections Standard (Joint committee of po
B-4 was identified as LiCoO ₂ in agreement with the pattern registered in 16-427 of the wder diffraction standards). The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic chart is shown in the table. The surface spacing is 2.03 ± 0.
The surface spacing for the peak intensity of 04Å 4.72 ± 0.05
The peak intensity of Å is shown in the table as an R value.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ 6H ₂ O and Co (NO ₃ ) ₃ .6H ₂ O were mixed at a molar ratio of 10: 9: 1, and calcined at 700 ° C. for 12 hours. LiNi _0.9 Co _0.1 O ₂ was obtained by vacuum-drying the powder obtained by washing and filtering the filtrate by filtration. This sample is designated as B-5.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ 6H ₂ O and Co (NO ₃ ) ₃ .6H ₂ O are mixed at a molar ratio of 40: 9: 1, and calcined at 700 ° C. for 12 hours. LiNi _0.9 Co _0.1 O ₂ was obtained by vacuum-drying the powder obtained by washing and filtering the filtrate by filtration. This sample is designated as B-6.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ 6H ₂ O and Co (NO ₃ ) ₃ .6H ₂ O are mixed at a molar ratio of 5: 4: 1, and calcined at 700 ° C. for 12 hours. LiNi _0.8 Co _0.2 O ₂ was obtained by vacuum-drying the powder obtained by washing and filtering the filtrate by filtration. This sample is B
-7.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
・ 6H ₂ O and Co (NO ₃ ) ₃ .6H ₂ O are mixed at a molar ratio of 20: 4: 1 and baked at 700 ° C. for 12 hours. LiNi _0.8 Co _0.2 O ₂ was obtained by vacuum-drying the powder obtained by washing and filtering the filtrate by filtration. This sample is designated as B-8.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O and 10: 9: 1 molar ratio, after firing at 700 ° C. 12 hours, calcined product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.9 Al _0.1 O ₂ . This sample is designated as B-9.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O and 15: 9: 1 molar ratio, after firing at 700 ° C. 12 hours, calcined product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.9 Al _0.1 O ₂ . This sample is designated as B-10.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O 5: 4: 1 molar ratio, after firing at 700 ° C. 12 hours, calcined product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.8 Al _0.2 O ₂ . This sample is B
-11.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
· 6H ₂ O and _{Al (NO 3) 3 · 9H} 2 O 7: 4: 1 molar ratio, after firing at 700 ° C. 12 hours, calcined product 1 by weight to 4 hours with water 50 weight The powder obtained by washing and separating the filtrate by filtration was vacuum dried at 100 ° C. to obtain LiNi _0.8 Al _0.2 O ₂ . This sample is B
-12.

When the X-ray diffraction characteristics of samples B-5 to B-12 using copper Kα rays were measured, they were all joint committees of power deflections standard (Joint committee of powder diffraction).
It is similar to the X-ray diffraction characteristic diagram of LiNiO ₂ registered in 9-63 of the standards), and it can be seen that it has the same structure. The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic chart is shown in the table. Also, the surface spacing is 2.03 ±
The interplanar spacing for the peak intensity of 0.02Å 4.72 ± 0.
The peak intensity of 03Å is shown as R value in the table.

Samples B-1 to B- synthesized in this way
The table shows the charge / discharge characteristics when a battery using 12 as the positive electrode active material was charged to 4.5 V at a current density of 0.5 mA / cm ² and then discharged to 3.0 V.

Of these, B-1 to B-4 and B-9 to
All the batteries using B12 as the positive electrode active material have a small discharge capacity, and it can be seen that the batteries produced in the examples of the present invention have excellent characteristics as compared with these batteries.

A coin battery using Samples B1 to B-12 as a positive electrode active material was newly prepared in the same manner, and a storage characteristic test was conducted as follows. First, these batteries were subjected to 3.0 V-4.5 at a current density of 0.5 mA / cm ² at 25 ° C.
The battery was charged and discharged 10 times in the voltage regulation range of V, the discharge capacity at the 10th time was measured, and after charging and reaching 4.5V, constant voltage charging was performed for 1 hour at 4.5V, and an overcharged state was set. . Next, these batteries were stored at 60 ° C. for 1 month, discharged again at 25 ° C. for the 11th time, the discharge capacity was measured, and the capacity retention rate after storage = (11th discharge capacity) /
(10th capacity) was examined. The results are shown in the table.

When compared with these batteries, it can be seen that the batteries produced in the examples of the present invention have excellent storage characteristics. As shown in the table, the storage characteristics of the batteries having no substitution, Samples B-1, B-2, and B-5 to B-10 containing Co as a substitution element are particularly poor. Therefore, it can be seen that the storage characteristics are improved by adding an element other than Co, which can be a cation, as the substituting element as in this example.

In Comparative Examples B-9 to B-12, M = A
at l, the interplanar spacing was 2.03 ± in the X-ray diffraction analysis.
The interplanar spacing for the peak intensity of 0.02Å 4.72 ± 0.
Although the peak intensity of 03Å is less than 1.2 times, these samples all have a small discharge capacity. On the other hand, as in this example, in the X-ray diffraction analysis, the plane spacing is 2.03 ±
The interplanar spacing for the peak intensity of 0.02Å 4.72 ± 0.
Compositional formula LiN whose peak intensity of 03Å is 1.2 times or more
i _1-x M _x O ₂ (M is an element that can be a cation other than Ni and Co that partially substitutes Ni of LiNiO ₂ , 0 <X ≦
It can be seen that when 0.5) is used, the discharge capacity is large and the characteristics are excellent.

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

As described above, according to the present invention,
A lithium battery having a small size and large charge / discharge energy and good storage characteristics can be constructed, and it has an advantage that it can be used in various fields including power sources of various portable electronic devices.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a coin battery according to an embodiment of the present invention.

FIG. 2 LiNi _0.8 Al _0.2 in Example 2 of the present invention
X-ray diffraction characteristic diagram of O ₂ .

FIG. 3 LiNi _0.9 Al _0.1 in Example 9 of the present invention
X-ray diffraction characteristic diagram of O ₂ .

[Explanation of symbols]

 1 Sealing Plate 2 Gasket 3 Positive Electrode Case 4 Negative Electrode 5 Separator 6 Positive Electrode Mixture Pellets

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Yamaki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Masahiro Ichimura 1-1-1 Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nippon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A plane spacing of 2.03 ± in X-ray diffraction analysis.
The interplanar spacing for the peak intensity of 0.02Å 4.72 ± 0.
Compositional formula LiN whose peak intensity of 03Å is 1.2 times or more
i _1-x M _x O ₂ (M is an element that can be a cation other than Ni and Co that partially substitutes Ni of LiNiO ₂ , 0 <X ≦
0.5) containing a complex oxide as a positive electrode active material, lithium or a compound thereof as a negative electrode active material, and chemically stable with respect to the positive electrode active material and the negative electrode active material, and having a lithium ion as described above. A lithium battery, characterized in that an electrolyte material is used as a material capable of carrying out an electrochemical reaction with the positive electrode active material or the negative electrode active material. 2. The positive electrode active material comprises Li / (Ni +) in atomic ratio.
M) ≧ 2, a nickel salt, the above M salt and a lithium salt are mixed, heated and calcined, and then excess lithium is washed away to obtain a composition formula LiNi _1-x M _x O ₂ (0 <X
The lithium battery according to claim 1, wherein the lithium battery is a complex oxide given by ≦ 0.5). 3. The M is a group IIIA or IIIB of the periodic table.
The lithium battery according to claim 1 or 2, wherein the lithium battery is a group element.