JP3339519B2 - Lithium battery - Google Patents

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 chargeable / dischargeable lithium secondary battery, and more particularly to a positive electrode active material which provides a battery having a large charge / discharge energy and excellent storage characteristics. It is.

[0002]

2. Description of the Related Art Non-aqueous electrolyte batteries using an alkali metal such as lithium or an alloy thereof as a negative electrode active material
The large discharge capacity and charge reversibility are both achieved by the insertion or intercalation reaction of the negative electrode metal ions into 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-shaped oxide such as titanium disulfide or vanadium pentoxide as a positive electrode active material has been proposed. The charge / discharge capacity was low, and the charge / discharge energy was not sufficient.

[0003] As a method of overcoming the above disadvantages,
It has been proposed to use a compound containing lithium as the positive electrode active material, and the voltage is as high as about 4 V by electrochemically desorbing lithium during the initial charge and simultaneously oxidizing the positive electrode active material. This enables a lithium battery 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.
l., 15 , 783 (1990)).

[0004]

The above-mentioned 4V-based positive electrode materials have a problem that the charge / discharge capacity of the high voltage portion is insufficient. In LiMn ₂ O ₄ , Li / Mn> 0.5
With the above charge, the voltage becomes 3 V due to the Jahn-Teller effect
It is thought to fall below, and its 4V range is 15
4 mAh / g (T. Ohzuku et al., J.
Electrochem. Soc., 137 , 769 (1990)). LiC
In oO ₂ , if a large amount of lithium is desorbed during charging with the aim 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. . In the case of LiCoO ₂ , there is also a disadvantage that a cobalt compound as a raw material is very expensive.

[0005] LiNiO ₂ is composed of LiMn ₂ O ₄ and LiMn ₂ O _4.
Promising in that it has better capacity characteristics than CoO ₂ and can achieve the largest energy density. But Li
Like CoO ₂ , the crystal structure is not maintained when a large amount of lithium is desorbed by charging, and thus has a disadvantage that storage characteristics are poor and practical application is difficult. For this reason, substitutional LiNi _1-x Co _x O ₂ has been studied, but has the disadvantage that the storage characteristics are still not excellent.

[0006]

An object of the present invention is to solve the current problems of insufficient charge / discharge capacity of the high voltage portion and poor storage characteristics as described above, and to provide a lithium battery having a large charge / discharge energy and excellent storage characteristics. The purpose is to do.

[0007]

Means for Solving the Problems In order to achieve the above object, in the lithium battery of the present invention, in the X-ray diffraction analysis, the interplanar spacing of 4.72 ± 0.03 ° relative to the peak intensity of 2.03 ± 0.02 °. Having a peak intensity of at least 1.2 times the composition formula LiNi _1-x M _x O ₂ (M is LiNiO ₂
Ni partially substituted for Ni, elements which can be a C o other than cations, 0 <composite oxide given by X ≦ 0.5)
Hints as a positive electrode active material, lithium or a compound as a negative electrode active material, the positive active material and the negative active chemically stable against substances, and the lithium ion positive electrode active material or the negative electrode active material and a substance moving may perform for the electrochemical reaction and an electrolyte material, a pre-Symbol positive electrode active material in an atomic ratio Li / (Ni + M) ≧ 2 and so as salts and lithium salts of the nickel salt M After being mixed and heated and calcined, excess lithium is washed and removed. The mixed oxide is a composite oxide represented by a composition formula LiNi _1-x M _x O ₂ (0 <X ≦ 0.5). It is a complex oxide which is an element of Group IIIA or IIIB of the periodic table.

The present invention will be described in more detail.

As a result of the inventor's intensive search for a material for a high energy density lithium battery having a large charge / discharge energy and excellent storage characteristics, as described above, a peak at a plane spacing of 2.03 ± 0.02 ° was found in the X-ray diffraction analysis. Ni peak intensity of interplanar spacing 4.72 ± 0.03 Å for the 1.2 times or more is composition formula _{LiNi 1-x M x O 2} (M is the intensity of partially replacing Ni of LiNiO _2, Co except cation capable of becoming elements, 0 <<br /> there are a double oxide given by X ≦ 0.5), a salt of the nickel salt M so that Li / (Ni + M) ≧ 2 in atomic ratio And a lithium salt mixed, heated and calcined, and then washed and removed of excess lithium, thereby obtaining a composite oxide represented by the composition formula LiNi _1-x M _x O ₂ (0 <X ≦ 0.5), particularly M is group IIIA of the periodic table Has confirmed that a lithium battery having higher charge / discharge energy and better storage characteristics than conventional lithium batteries can be constructed by using a complex oxide which is an element of group IIIB as a positive electrode active material. Was completed.

The reason why the capacity of the lithium battery of the present invention is increased as compared with the prior art is considered as follows.
First, LiNi _1-x M _x O ₂ (M is Ni of LiNiO ₂
The partially substituted for Ni, elemental which can be a Co other than cation, 0 <To X ≦ 0.5) sufficiently express the capacity characteristics of LiNiO ₂ is a component which acts as the active material in the It is necessary that M be selectively substituted with nickel, nickel and the element M be suppressed from being mixed into the surface where lithium ions are present, and lithium ion conductivity be improved when used as an active material of a lithium battery. For this purpose, in the LiNi _1-x M _x O ₂ X-ray diffraction analysis, the peak intensity at the plane spacing 4.72 ± 0.03 ° with respect to the peak intensity at the plane spacing 2.03 ± 0.02 ° is 1.2 times or more. It is necessary to be.

It is considered that the reason why the storage characteristics are improved is that the structural stability in a 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, no improvement in storage characteristics is observed. This is considered to be because the storage characteristics of the battery using LiCoO ₂ as the positive electrode active material are poor, and therefore, even if LiCoO ₂ is partially contained, it cannot contribute to improvement in stability. When M is an element belonging to the group IIIA or IIIB of the periodic table, the LiMO ₂ component contained in the crystal is not oxidized by charging and is always used as an element for maintaining the stability of the positive electrode active material. Since it works, particularly excellent storage characteristics can be realized.

As described above, the replacement element M is LiNiO ₂
It is preferable to use an element that forms a solid solution so as to maintain the crystal structure of and selectively replaces nickel. 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 those of nickel. Specifically, aluminum, gallium, indium, manganese, chromium, vanadium,
Examples include one or more of iron, titanium, copper, zinc, scandium, indium, yttrium, lanthanoids, and boron. In particular, from the viewpoint of storage characteristics, scandium, yttrium,
One or more of lanthanoids, boron, aluminum, indium and the like can be mentioned as promising replacement elements.

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

Here, LiNi _1-x M _x O ₂ (0 <X ≦ 0.
At the time of synthesizing 5), mixing at an atomic ratio of Li / (Ni + M) <2 and firing at a temperature of 700 ° C. or higher required for generation causes lithium salts to be lost by sublimation, and thus the atomic ratio Li / (Ni + M) is significantly reduced from 1.0. In this case, a phenomenon is observed in which nickel ions and ions of the substitution element M are mixed into the surface of the fired product on which lithium ions are present, which inhibits the conduction of lithium ions and lowers them. Therefore, the lithium salt is prevented from disappearing, and LiNi
Atomic ratio Li / _1-x M _x O ₂ (0 <X ≦ 0.5)
In order to make (Ni + M) close to 1.0, it is preferable to mix a nickel salt, a salt of a substitution element M, and a lithium salt so that the atomic ratio becomes Li / (Ni + M) ≧ 2 at the time of synthesis and heat and bake the mixture. It is.

Further, LiNi _1-x M _x O ₂ (0 <X ≦ 0.
In the synthesis of 5), the unreacted lithium which does not sublimate and is excessive becomes a lithium salt such as lithium oxide, lithium carbonate, lithium hydroxide, etc.
_Although a mixture of _1-x M _x O ₂ (0 <X ≦ 0.5) and these unreacted lithium salts is used, this calcined powder has a high solubility of these lithium salts and a LiNi _1-x M _x O ₂ (0 <X ≦
By washing with a solvent which does not decompose 0.5), only the excess lithium salt can be eluted and removed. If a battery is manufactured with unreacted lithium mixed, the capacity is reduced and the battery is short-circuited.

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 C., more preferably 700 C. to 800 C. to minimize the disappearance of the lithium salt.

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

In order 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 compression-molded on a support such as stainless steel, or A conductive powder such as acetylene black is mixed to impart conductivity to the mixture powder, and a binder powder such as polytetrafluoroethylene is further added as necessary, 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 in the form of a slurry to a metal substrate.

Lithium as the negative electrode active material is formed as a negative electrode by forming a sheet in the same manner as that of a general lithium battery, or by pressing the sheet against a conductive net such as nickel or stainless steel. As the negative electrode active material, a lithium alloy such as a lithium-aluminum alloy can be used in addition to lithium. Further, a 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 a positive electrode by a charging reaction can be doped to obtain a carbon-lithium negative electrode or the like.

[0020] As the electrolyte, such as dimethoxyethane, 2-methyltetrahydrofuran, ethylene carbonate, methyl formate, dimethyl sulfoxide, propylene carbonate, acetonitrile, butyrolactone, dimethyl formamide, dimethyl carbonate, in an organic solvent such as diethyl carbonate, LiAsF _6, L
A non-aqueous electrolyte solvent in which a Lewis acid such as iBF ₄ , LiPF ₆ , LiAlCl ₄ , and LiClO ₄ is dissolved, or a solid electrolyte can be used.

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

[0022]

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

[0023]

Embodiment 1 FIG. 1 is a sectional view of a coin battery which is a specific example of a battery according to the present invention. In FIG. 1, 1 is a sealing plate, 2 is a gasket, 3 is a positive electrode case, 4 is a negative electrode, 5 is a separator,
Reference numeral 6 denotes a positive electrode mixture pellet.

The positive electrode active materials include LiOH.H ₂ O and Ni
(NO ₃ ) ₂ .6H ₂ O and Al (NO ₃ ) ₃ .9H ₂ O
LiNi _0.8 Al _0.2 O ₂ obtained by mixing at a molar ratio of 0: 4: 1 and calcining 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 radiation, a characteristic diagram as shown in FIG. 2 was obtained, and the joint committee of powder diffraction standard (Joint committee of powder diffraction) was obtained.
ction standards) 9-63 registered LiNiO ₂
It is similar to the X-ray diffraction characteristic diagram of FIG. The size of the hexagonal unit cell calculated from this X-ray diffraction characteristic diagram is shown in the table. In addition, the plane spacing for a peak intensity of 2.03 ± 0.02 ° 4.
The peak intensity of 72 ± 0.03 ° is shown in the table as an R value.

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

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

The tenth capacity retention rate (= the tenth discharge capacity) when the battery was charged and discharged under a voltage regulation of 3.0 V to 4.5 V at a charge / discharge current density of 0.5 mA / cm ² , respectively. / 1st discharge capacity) is shown in the table. It is apparent from this that the capacity decrease due to the cycle is small.

[0028]

Examples 2 to 16 In Examples 2 to 16, lithium batteries manufactured in the same manner as in Example 1 except that samples A2 to A16 synthesized as follows were used as the positive electrode active materials, respectively. The charge and discharge characteristics were studied.

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 called A
-2.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and Al (NO ₃ ) ₃ .9H ₂ O are mixed at a molar ratio of 50: 4: 1, and calcined at 700 ° C. for 12 hours. 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 called A
-3.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and Al (NO ₃ ) ₃ .9H ₂ O were mixed at a molar ratio of 40: 7: 3, and calcined at 700 ° C. for 12 hours. 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 called A
-4.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and Al (NO ₃ ) ₃ .9H ₂ O are mixed at a molar ratio of 8: 1: 1 and fired at 700 ° C. for 12 hours.
The powder was washed with 50 parts by weight of water for 4 hours, and the filtrate obtained by separating the filtrate by filtration was vacuum-dried at 100 ° C. to obtain LiNi _0.5 Al _0.5 O ₂ . A-
5 is assumed.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and Ga (NO ₃ ) ₃ .9H ₂ O are mixed at a molar ratio of 20: 4: 1, and calcined at 700 ° C. for 12 hours. The powder obtained by washing and separating the filtrate by filtration was vacuum-dried at 100 ° C. to obtain LiNi _0.8 Ga _0.2 O ₂ . This sample is called A
−6.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and B ₂ O ₃ are mixed in a molar ratio of 40: 8: 1,
After calcination at 700 ° C. for 12 hours, the powder obtained by washing with 1 part by weight of water and 50 parts by weight of water for 4 hours and separating the filtrate by filtration is 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 are mixed at a molar ratio of 40: 8: 1, and calcined at 700 ° C. for 12 hours, washed with 50 weights of water per 1 weight of the calcined material for 4 hours, and filtered by filtration. The powder obtained by separating the liquid is vacuum-dried at 100 ° C.
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 were mixed at a molar ratio of 40: 9: 1, and calcined at 700 ° C. for 12 hours, and then 4 hours with 50 wt. 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 called A
−9.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and Ga (NO ₃ ) ₃ .9H ₂ O were mixed at a molar ratio of 40: 9: 1, and calcined at 700 ° C. for 12 hours. 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 called A
-10.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and B ₂ O ₃ are mixed at a molar ratio of 80: 18: 1, and calcined at 700 ° C. for 12 hours, washed with 50% water for 1 hour per 1 weight of the calcined material, and filtered by filtration. The powder obtained by separating the liquid is vacuum-dried at 100 ° C.
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, washed with 50 weights of water per 1 weight of the calcined material for 4 hours, and filtered by filtration. The powder obtained by separating the liquid is vacuum-dried at 100 ° C.
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 were mixed at a molar ratio of 40: 9: 1, and calcined at 700 ° C. for 12 hours. 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 called A
-13.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
Mixing 6H ₂ O and MnO in a molar ratio of 40: 9: 1,
After calcination at 700 ° C. for 12 hours, the powder obtained by washing with 1 part by weight of water and 50 parts by weight of water for 4 hours and separating the filtrate by filtration is 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 were mixed at a molar ratio of 40: 9: 1, and calcined at 700 ° C. for 12 hours. 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 called 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 calcination at 700 ° C. for 12 hours, the powder obtained by washing with 1 part by weight of water and 50 parts by weight of water for 4 hours and separating the filtrate by filtration is 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 characteristic diagrams of the samples A-2 to A-16 using the copper Kα ray were measured, they were all found to be joint committee of powder diffraction standards (Joint committee of powder diffraction).
It is similar to the X-ray diffraction characteristic diagram of LiNiO ₂ registered in Standards 9-63, and it can be seen that it has the same structure. Further, the size of the hexagonal unit cell calculated from the X-ray diffraction characteristic diagram is shown in the table. 2.03 ±
Interplanar spacing 4.72 ± 0.2 for a peak intensity of 0.02 °.
The peak intensity of 03 ° is shown in the table as an R value. A-9
FIG. 3 shows the X-ray diffraction characteristics of the sample.

Samples A-2 to A- thus synthesized
The table shows the charge / discharge characteristics when the battery using No. 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. All have the advantage of being capable of large capacity discharge at high voltage and of being usable as high energy density batteries.

These batteries were charged at 0.5 mA / cm ²
Table 10 shows the tenth capacity retention ratio (= the tenth discharge capacity / the first discharge capacity) when voltage-controlled charging and discharging were performed at 3.0 V to 4.5 V, respectively, at the charging and discharging current densities of FIG. As is clear from this, it can be seen that the capacity decrease due to the cycle is small.

In Examples 1 to 16, LiNi _1-x M _x O ₂ (0 <
X ≦ 0.5) as the positive electrode active material, the charge / discharge characteristics of the battery were shown.
The composition is not limited to the substitution ratio, and the peak intensity at the interplanar spacing of 4.72 ± 0.03 ° is at least 1.2 times the peak intensity at the interplanar spacing of 2.03 ± 0.02 ° in X-ray diffraction analysis. Formula LiNi _1-x M _x O ₂ (M is LiN
iO Ni a _second Ni is partially substituted, an element that can be a Co other than cation, 0 <a mixed oxide given by X ≦ 0.5), Li / atomic ratio (Ni + M) ≧ 2 The composition formula LiNi _1-x M _x O ₂ (0 <X ≦ 0.0) obtained by mixing the nickel salt, the salt of M and the lithium salt, heating and calcining the mixture so that excess lithium is removed by washing.
5) The double oxide given in 5), especially the above-mentioned M is I in the periodic table.
It is needless to say that the same effect is obtained when a double oxide which is a group IIA or IIIB element is used as the positive electrode active material.

[0048]

Example 17 A coin battery using Samples A-1 to A-16 as positive electrode active materials was newly prepared in the same manner as in Examples 1 to 16, and a storage characteristic test was performed as follows. First, these batteries were charged and discharged 10 times at 25 ° C. at a current density of 0.5 mA / cm ² within a voltage regulation range of 3.0 V to 4.5 V, and the 10th discharge capacity was measured. After the voltage reached 0.5 V, the battery was charged at a constant voltage for 1 hour with the voltage kept at 4.5 V, and the battery was overcharged. Next, these batteries were heated at 60 ° C. for 1 hour.
It was stored for 15 months, the eleventh discharge was performed again at 25 ° C., the discharge capacity was measured, and the capacity retention rate after storage = (the eleventh discharge capacity) / (the tenth capacity) was examined. The results are shown in the table. As is clear from this, it can be seen that the batteries of Samples A-1 to A-16 have good storage characteristics. Also M
Is an element of Group IIIA or IIIB of the Periodic Table, it can be seen that it has particularly good storage.

In Example 17, LiNi _1-x M _x O ₂ (0 <X ≦
0.5) was used as the positive electrode active material, and the storage characteristics of the battery were shown. However, the present invention is not limited to the types of these substitution elements M and the percentage of substitution. A composition formula LiNi _1-x M _x O ₂ (M is LiNiO _{2) in which} the peak intensity at a spacing of 4.72 ± 0.03 ° with respect to the peak intensity at 03 ± 0.02 ° is 1.2 times or more.
Ni partially substituted for Ni, elements which can be a Co other than cations, 0 <composite oxide given by X ≦ 0.5)
A nickel salt, a salt of M and a lithium salt are mixed and heated and baked so that the atomic ratio of Li / (Ni + M) ≧ 2, and then the excess lithium is removed by washing to obtain a composition formula LiNi. _1-x M _x O 2 composite oxide given by (0 <X ≦ 0.5), IIIA especially the M is the periodic table
It is needless to say that the same effect is obtained when a double oxide which is a Group III or Group IIIB element is used as the positive electrode active material.

[0050]

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

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O is mixed at a molar ratio of 1: 1.
After firing for 4 hours, 50 weight of water is added to 4 weight of fired product.
After washing for an hour and separating the filtrate by filtration,
By vacuum drying at 0 ° C., LiNiO ₂ was obtained.
This sample is designated as B-1. Sample B-1 using copper Kα ray
When the X-ray diffraction characteristic diagram was measured, the Joint committee of powder diffraction standard was used.
s) matches the pattern registered in 9-63, B-1
Was identified as LiNiO ₂ . The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic diagram is shown in the table. In addition, the peak intensity at an interplanar distance of 4.72 ± 0.03 ° with respect to the peak intensity at an interplanar distance of 2.03 ± 0.02 ° is shown in the table as an R value.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O is mixed at a molar ratio of 4: 1.
After calcination for 1 hour, the powder obtained by washing with 50 weight of water for 1 hour with respect to 1 weight of the baked product for 4 hours and separating the filtrate by filtration was used as 100 powder.
Vacuum drying was performed at ℃ to obtain LiNiO ₂ . This sample is designated as B-2. When the X-ray diffraction characteristic diagram of the sample B-2 was measured using copper Kα ray, the joint committee of powder diffraction standard (Joint committee of powder diffraction standard) was obtained.
s) matches the pattern registered in 9-63, B-2
Was identified as LiNiO ₂ . The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic diagram is shown in the table. In addition, the peak intensity at a spacing of 4.72 ± 0.03 ° relative to the peak intensity at a spacing of 2.03 ± 0.02 ° 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 fired at 900 ° C. for 1 day to obtain a black powder. This sample is designated as B-3. When the X-ray diffraction characteristic diagram of the sample B-1 was measured using copper Kα radiation, the joint committee of power deflections standard (Joint committeeof
According to the pattern registered in powder diffraction standards) 16-427, B-3 was identified as LiCoO ₂ . The size of the hexagonal unit cell calculated from the X-ray diffraction characteristic diagram is shown in the table. 2.03 ±
Interplanar spacing 4.72 ± 0.2 for a peak intensity of 0.04 °.
The peak intensity at 05 ° is shown in the table as an R value.

Then, Li ₂ CO ₃ and CoCO ₃ were mixed at a molar ratio of 2: 1 and then fired 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 the sample B-1 was measured using copper Kα ray, the joint committee of power deflections standard (Joint committee ofpo
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 diagram is shown in the table. The surface spacing is 2.03 ± 0.
Surface spacing 4.72 ± 0.05 for peak intensity of 04 °
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 are mixed at a molar ratio of 10: 9: 1, and calcined at 700 ° C. for 12 hours. The powder obtained by washing and separating the filtrate by filtration was vacuum-dried at 100 ° C. to obtain LiNi _0.9 Co _0.1 O ₂ . 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. The powder obtained by washing and separating the filtrate by filtration was vacuum-dried at 100 ° C. to obtain LiNi _0.9 Co _0.1 O ₂ . 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. The powder obtained by washing and separating the filtrate by filtration was vacuum-dried at 100 ° C. to obtain LiNi _0.8 Co _0.2 O ₂ . This sample is
−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 calcined at 700 ° C. for 12 hours. The powder obtained by washing and separating the filtrate by filtration was vacuum-dried at 100 ° C. to obtain LiNi _0.8 Co _0.2 O ₂ . 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 were mixed at a molar ratio of 10: 9: 1, and calcined at 700 ° C. for 12 hours. 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 were mixed at a molar ratio of 15: 9: 1, and calcined at 700 ° C. for 12 hours. 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 were mixed at a molar ratio of 5: 4: 1, and calcined at 700 ° C. for 12 hours. 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
It is assumed to be -11.

Next, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O and Al (NO ₃ ) ₃ .9H ₂ O are mixed at a molar ratio of 7: 4: 1 and calcined at 700 ° C. for 12 hours. 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
−12.

When the X-ray diffraction characteristic diagrams of the samples B-5 to B-12 using copper Kα radiation were measured, all were measured by the Joint Committee of Powder Diffraction Standard (Joint committee of powder diffraction standard).
It is similar to the X-ray diffraction characteristic diagram of LiNiO ₂ registered in Standards 9-63, and it can be seen that it has the same structure. In addition, the size of the hexagonal unit cell calculated from the X-ray diffraction characteristic diagram is shown in the table. 2.03 ±
Interplanar spacing 4.72 ± 0.2 for a peak intensity of 0.02 °.
The peak intensity of 03 ° is shown in the table as an R value.

The samples B-1 to B-
The table below shows the charge / discharge characteristics when a battery using No. 12 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.

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 manufactured in Examples of the present invention have excellent characteristics as compared with these batteries.

A coin battery using the samples B-1 to B-12 as positive electrode active materials was newly prepared in the same manner, and the storage characteristics were tested as follows. First, these batteries were subjected to a current density of 0.5 mA / cm ² at 25 ° C. and a voltage of 3.0 V-4.
10 cycles of charge / discharge in a voltage regulation range of 5 V
The discharge capacity was measured the first time, and the battery was charged. After the battery reached 4.5 V, the battery was charged at a constant voltage of 4.5 V for one hour, and the battery was overcharged. Next, these batteries were stored at 60 ° C. for one month, discharged again at 25 ° C. for the eleventh time, and the discharge capacity was measured.
Capacity retention rate after storage = (eleventh discharge capacity) / (10
Volume) was examined. The results are shown in the table.

As compared with these batteries, it is understood that the batteries manufactured in the examples of the present invention have excellent storage characteristics. As can be seen from the table, the batteries having unsubstituted samples B-1 and B-2 and samples B-5 to B-10 using Co as a substitution element have particularly poor storage characteristics. Therefore, it can be seen that the storage characteristics are improved by adding an element that can be a cation other than Co as a substitution element as in this example.

In Comparative Examples B-9 to B-12, M = A
1, 2.03 ± 2 in X-ray diffraction analysis
Interplanar spacing 4.72 ± 0.2 for a peak intensity of 0.02 °.
The samples having a peak intensity of 03 ° less than 1.2 times, all of which have a small discharge capacity. On the other hand, as in this example, in the X-ray diffraction analysis, the plane spacing was 2.03 ±
Interplanar spacing 4.72 ± 0.2 for a peak intensity of 0.02 °.
Composition formula LiN whose peak intensity at 03 ° is 1.2 times or more
_{i 1-x M x O 2} (M is Ni partially replace Ni of LiNiO _2, elemental that can be a C o other than cation, 0
<X ≦ 0.5) , and the atomic ratio is Li / (Ni +
M) the nickel salt and the salt and
After mixing and heating and baking the lithium salt, excess lithium is removed.
When the peroxide obtained by washing and removing is used, it is understood that the discharge capacity is large and has excellent characteristics.

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

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

[Brief description of the drawings]

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

FIG. 2 shows LiNi _0.8 Al _0.2 in Example 2 of the present invention.
X-ray diffraction characteristic diagram of O _2.

FIG. 3 shows LiNi _0.9 Al _0.1 in Example 9 of the present invention.
X-ray diffraction characteristic diagram of O _2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing plate 2 Gasket 3 Positive electrode case 4 Negative electrode 5 Separator 6 Positive electrode material pellet

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Yamaki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Masahiro Ichimura 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (56) References JP-A-5-290845 (JP, A) JP-A-6-96768 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/58 H01M 4/02 H01M 10/40

Claims (2)

(57) [Claims] 1. An X-ray diffraction analysis in which the plane spacing is 2.03 ±
Interplanar spacing 4.72 ± 0.2 for a peak intensity of 0.02 °.
Composition formula LiN whose peak intensity at 03 ° 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 replace Ni of LiNiO ₂ ,
<X ≦ 0.5) as a positive electrode active material, and lithium or a compound thereof as a negative electrode active material;
A material which is chemically stable to the positive electrode active material and the negative electrode active material, and is capable of performing lithium ion electrochemical transfer with the positive electrode active material or the negative electrode active material as an electrolyte material, A composition formula of LiNi obtained by mixing and heating and calcining a nickel salt, the salt of M, and a lithium salt so that the positive electrode active material has an atomic ratio of Li / (Ni + M) ≧ 2, and then washing and removing excess lithium.
_1-x M _x O 2 lithium battery which is a double oxide given by (0 <X ≦ 0.5). 2. The method according to claim 1, wherein M is group IIIA or I in the periodic table.
The lithium battery according to claim 1, wherein the lithium battery is a Group IIB element.