JPH06111822A - Lithium battery - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a small-sized lithium battery with large charge / discharge energy at low cost. [Structure] Interplanar spacing 2.0 ± 0.02 in X-ray diffraction analysis
Double oxide Li _x NiO ₂ having a peak spacing of 4.74 ± 0.04 Å with respect to the peak intensity of
(X ≦ 1.0) is used as the positive electrode active material 6. [Effect] It is advantageous in that a small lithium battery having a large charge / discharge energy can be constructed at a low cost and can be used in various fields including a power source for various portable electronic devices.

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 improvement of a positive electrode active material which can be charged and discharged with a large capacity.

[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 lithium ion conductivity was poor, 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 in particular, the voltage is as high as about 4 V by electrochemically desorbing lithium during initial charging and simultaneously oxidizing the positive electrode active material. Moreover, it enables a lithium battery having excellent lithium ion conductivity. Examples of this are LiMn ₂ O ₄ (JP 58-34414 A), LiCoO ₂ (Mizushima et al., Mat.Res.Bul).
l., 15 , 783 (1990), LiNiO ₂ (JBGoodenou
gh et al., Mat.Res.Bull., 20 , 1137 (1985)), but all of them have a problem that the charge / discharge capacity of the high voltage part is not sufficient. The reason for this is that LiMn
It is considered that the discharge voltage of Li / Mn> 0.5 or more in ₂ O ₄ causes the voltage to drop to 3 V or less due to the Yarn-Teller effect (T.Ohzuku et al., J. Electrochem.
Soc., 137 , 769 (1990)), and LiCoO ₂ and LiNiO ₂ have insufficient lithium ion conductivity and a low active material utilization rate. In particular, LiCoO ₂ has a drawback that the cobalt compound as a raw material is very expensive. Therefore, it has been attempted to increase the capacity of LiNiO ₂ which has the same structure as LiCoO ₂ and can be synthesized with an inexpensive raw material. No capacity was obtained (T. Ohzuku et al., Chem. Express., 5 , 733 (1990), etc.). This is considered to be due to the following reasons.
That is, the vapor pressure of the lithium salt is high at the firing temperature of 700 ° C. or higher required for the production of LiNiO ₂ , and when the mixed atom ratio of the lithium salt and the nickel salt is Li / Ni <1.2, the firing product is Value of Li / Ni of 1.0 significantly decreases from 1.0. In the case of LiCoO ₂ , although the normal synthesis temperature is 800 ° C. or higher at which the vapor pressure of the lithium salt is considered to be high, a form in which the lithium salt is less likely to volatilize compared to LiNiO ₂ is formed at a relatively low temperature. Therefore, the tendency that the Li / Co value significantly decreases from 1.0 is not remarkable. In LiNiO ₂ , as described above, the Li / Ni value of the fired product was remarkably reduced from 1.0, and at this time nickel ions were mixed in the surface where lithium ions were present, and the interplanar spacing was 2.05 in X-ray diffraction analysis. ± 0.02Å
It is observed that the peak intensity at the interplanar spacing of 4.74 ± 0.04Å is less than 1.2 times the peak intensity at 1. In this case, since diffusion of lithium ions is hindered by nickel ions, it is considered that sufficient charge / discharge capacity cannot be obtained when used as an active material of a battery.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned problems and to provide a small-sized lithium battery with large charge / discharge energy at low cost.

[0005]

In order to achieve the above object, in the lithium battery of the present invention, a lithium salt and a nickel salt are mixed in an atomic ratio of Li / Ni ≧ 1.2 and heated and baked. Double oxidation in which the peak intensity of the interplanar spacing of 4.74 ± 0.04Å is 1.2 times or more the peak intensity of the interplanar spacing of 2.05 ± 0.02Å in the X-ray diffraction analysis obtained by washing away excess lithium. Thing Li _x NiO ₂ (X ≦
1.0) as a positive electrode active material, lithium or a compound thereof as a negative electrode active material, is chemically stable to the positive electrode active material and the negative electrode active material, and lithium ions are the positive electrode active material or the positive electrode active material. It is characterized in that a substance that can move to cause an electrochemical reaction with the negative electrode active material is an electrolyte substance.

The present invention will be described in more detail.

As described above, a lithium salt and a nickel salt are mixed in an atomic ratio of Li / Ni ≧ 1.2, heated and calcined, and then excess lithium is washed away to obtain a surface in an X-ray diffraction analysis. A complex oxide Li _x NiO ₂ (X ≦ 1.x) in which the peak intensity of the interplanar spacing 4.74 ± 0.04Å is 1.2 times or more the peak intensity of the interval 2.05 ± 0.02Å.
It was confirmed that by using 0) as the positive electrode active material, a lithium battery having a larger charge / discharge energy than the conventional lithium battery and an excellent cycle property can be constructed, and the present invention was completed with the recognition. The lower limit value of X is preferably 0.9 or more. This is because the charging / discharging efficiency may decrease, as is clear from the examples described below.

The reason why the lithium battery of the present invention has a larger capacity than the prior art is estimated as follows. That is, the lithium salt and the nickel salt are Li / Ni in atomic ratio.
By mixing and heating and firing as ≧ 1.2,
Li _x Ni obtained by supplementing lithium lost by evaporation during firing and washing and removing excess lithium from the fired product
The X value in O ₂ can be brought close to 1.0, and nickel ions are suppressed from mixing into the surface on which lithium ions are present.
Interplanar spacing for a peak intensity of 0.02Å 4.74 ± 0.
The peak intensity of 04Å is 1.2 times or more, and it is presumed that a material having good lithium ion conductivity when used as an active material of a lithium battery and having a high active material utilization rate can be synthesized. When the mixed atomic ratio Li / Ni is less than 1.2, it is insufficient to compensate for the evaporation of the lithium salt that occurs at 700 ° C. or higher, and the X value in Li _x NiO ₂ that occurs is 1.
Since it cannot approach 0, Li / Ni during mixing
It is necessary that the ratio is 1.2 or more.

Regarding the firing temperature, Li _x NiO ₂ (X ≦
1.0) requires a temperature of 700 ° C. or higher, and when the temperature exceeds 800 ° C., the lithium salt evaporates violently. Therefore, in order to synthesize an active material having a high X value and good lithium ion conductivity. Is preferably fired at 700 ° C. or higher and 800 ° C. or lower.

Further, since excess lithium becomes a lithium salt such as lithium oxide, lithium carbonate and lithium hydroxide, the powder after firing has high solubility of Li _x NiO ₂ (X ≦ 1.0) and these lithium salts. Excessive lithium can be removed by washing with a solvent such as water, acid or alcohol.

The synthesizing method used in the present invention is an extremely simple method, and the fact that inexpensive nickel can be used in place of expensive cobalt is also of high industrial value.

As the nickel salt and lithium salt, hydroxides, carbonates, sulfates, nitrates, halogen compounds and the like can be used.

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 nickel or stainless steel. Alternatively, a conductive powder such as acetylene black is mixed to give conductivity to the mixture powder, and a binder powder such as polytetotafluoroethylene is further added to the mixture as needed, and the mixture is added to a metal container. Or press-mold the above mixture onto a support such as stainless steel. Alternatively, it is formed by a means such as making the above mixture into a slurry and coating it 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 negative electrode for a so-called 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 an 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 solution in which a Lewis acid such as iBF ₄ , LiPF ₆ , LiAlCl ₄ or LiClO ₄ is dissolved can be used.

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

[0017]

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

[0018]

EXAMPLE 1 FIG. 1 is a cross-sectional view of a coin-type battery which is one 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 lithium negative electrode, and 5 is a lithium negative electrode. A separator, 6 is a positive electrode material mixture pellet.

The positive electrode active material includes LiOH.H ₂ O and Ni.
(NO ₃₎ the ₂ · 6H ₂ O 4: 1 molar ratio to evaporate the water was stirred for 4 hours was dissolved in water, the obtained powder 700
Li _0.99 Ni obtained by firing at 120 ° C. for 12 hours, washing with 50 weight of water for 4 hours with respect to 1 weight of the fired product, and separating the filtrate by filtration to obtain a powder and vacuum drying at 100 ° C.
O ₂ was used. The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is designated as A1. An X-ray diffraction characteristic diagram of Sample A1 using copper Kα rays is shown in FIG. The powder of the obtained sample A1 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 (thickness: 0.
5 mm, diameter 15 mm). First, a metallic lithium negative electrode 4 placed under pressure on a stainless steel sealing plate 1 is inserted into a recess of a polypropylene gasket 2, and a polypropylene microporous separator 5 and a positive electrode are placed on the metallic lithium negative electrode 4. The mixture 6 was arranged in this order, and 1 N solution of LiClO ₄ dissolved in an equal volume mixed solvent of propylene carbonate and 2-dimethoxyethane was injected as an electrolytic solution and impregnated thereinto, respectively, and then a positive electrode made of stainless steel was prepared. By covering the case 3 and caulking, a thickness of 2 m
A coin-type battery having a diameter of m and a diameter of 23 mm was produced.

A battery using the sample A1 thus produced as a positive electrode active material was tested at a current density of 0.5 mA / cm ² .
FIG. 3 shows a charge / discharge curve when the battery was charged to 5V and then discharged to 3.0V. It draws a flat discharge curve near 4 V, and has the advantage that it can be used as a positive electrode material for high energy density batteries. In addition, X value, surface spacing 2.05 ±
Interplanar spacing for a peak intensity of 0.02Å 4.74 ± 0.
Table 1 shows the peak intensity of 04Å and the first charge / discharge characteristics.

The capacity maintenance rate (discharge capacity value of the first discharge is the discharge capacity value when the battery is charged and discharged at a voltage regulated voltage of 3.0 V to 4.5 V at a charge and discharge current density of 0.5 mA / cm ^2. Table 2 shows the ratio (%) divided by the capacity value. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0022]

[Example 2] L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.94 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 1: 1 and stirred for 4 hours, and then water was evaporated.
OH / H ₂ O powder (3 parts by weight) was mixed and calcined at 700 ° C. for 12 hours, washed with 50 parts by weight of water for 4 hours, and the filtrate was separated by filtration to obtain a powder at 100 ° C.
Li _0.94 NiO ₂ was obtained by vacuum drying in. The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is designated as A2.

The X value of the sample A2 thus synthesized,
The peak intensity of the interplanar spacing of 2.05 ± 0.02Å and the peak intensity of the interplanar spacing of 4.74 ± 0.04Å, and the battery using the sample A2 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. It has a merit that it can discharge a large capacity at high voltage and can be used as a positive electrode material for high energy density batteries.

In addition, this battery was maintained at a capacity of 3.0 V-4.5 V at a charge / discharge current density of 0.5 mA / cm ² , and the capacity retention rate (the discharge capacity value was the first discharge capacity). The ratio (%) divided by the value is shown in Table 2. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0026]

Example 3 L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.92 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 1: 1 and stirred for 4 hours, and then water was evaporated.
OH / H ₂ O powder (3 parts by weight) was mixed and calcined at 800 ° C for 12 hours, and 1 part by weight of the calcined product was washed with 50% of water for 4 hours, and the filtrate was separated by filtration to obtain a powder at 100 ° C.
Li _0.92 NiO ₂ was obtained by vacuum drying at. The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is designated as A3.

The X value of the sample A3 thus synthesized,
The peak intensity of the interplanar spacing is 2.05 ± 0.02Å, the peak intensity of the interplanar spacing is 4.74 ± 0.04Å, and the battery using the sample A3 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. It has a merit that it can discharge a large capacity at high voltage and can be used as a positive electrode material for high energy density batteries.

Further, the capacity maintenance rate (discharge capacity value at the time of the first discharge capacity was measured when the battery was charged / discharged at a charge / discharge current density of 0.5 mA / cm ² at a voltage regulated charge of 3.0 V-4.5 V. The ratio (%) divided by the value is shown in Table 2. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0030]

Example 4 L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.94 NiO ₂ was used.

Firstly LiNO ₃ and _{Ni (NO 3) 2 · 6H} 2 O
Were mixed at a molar ratio of 4: 1 and calcined at 700 ° C. for 12 hours, washed with 50 parts by weight of water for 4 hours per 1 weight of the calcined product, and the filtrate was separated by filtration to obtain a powder at 100 ° C. Li _0.94 NiO ₂ was obtained by vacuum drying. The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is designated as A4.

The X value of the sample A4 thus synthesized,
The peak intensity of the interplanar spacing of 2.05 ± 0.02Å and the peak intensity of the interplanar spacing of 4.74 ± 0.04Å, and the battery using the sample A4 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. It has a merit that it can discharge a large capacity at high voltage and can be used as a positive electrode material for high energy density batteries.

Further, the capacity maintenance rate (discharge capacity value at the time of the first discharge capacity was measured when the battery was charged and discharged at a voltage regulated voltage of 3.0 V to 4.5 V at a charge and discharge current density of 0.5 mA / cm ^2. The ratio (%) divided by the value is shown in Table 2. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0034]

[Example 5] L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.97 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 10: 1, stirred for 4 hours, evaporated to evaporate water, calcined at 700 ° C. for 12 hours, and washed with 100 weight of water for 4 hours per 1 weight of the calcined product. Was separated by filtration and the powder obtained was vacuum dried at 100 ° C. to obtain Li _0.97 NiO ₂ . The chemical composition is IC
It was calculated from the analysis value of nickel by P emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is designated as A5.

The X value of sample A5 thus synthesized,
The peak intensity of the interplanar spacing is 2.05 ± 0.02Å and the peak intensity of the interplanar spacing is 4.74 ± 0.04Å, and the battery using the sample A5 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. It has a merit that it can discharge a large capacity at high voltage and can be used as a positive electrode material for high energy density batteries.

The capacity retention ratio (discharge capacity value at the time of the first discharge capacity was measured when the battery was charged and discharged at a voltage regulated voltage of 3.0 V to 4.5 V at a charge / discharge current density of 0.5 mA / cm ^2. The ratio (%) divided by the value is shown in Table 2. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0038]

[Example 6] L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.93 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 2: 1 and stirred for 4 hours, then water was evaporated, and the mixture was calcined at 700 ° C. for 12 hours, washed with 50 parts by weight of water for 4 hours, and filtered. Was separated by filtration and the powder obtained was vacuum dried at 100 ° C. to obtain Li _0.93 NiO ₂ . The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is A
6

The X value of the sample A6 thus synthesized,
The peak intensity of the interplanar spacing is 2.05 ± 0.02Å, the peak intensity of the interplanar spacing is 4.74 ± 0.04Å, and the battery using the sample A6 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. It has a merit that it can discharge a large capacity at high voltage and can be used as a positive electrode material for high energy density batteries.

The capacity retention rate (discharge capacity value at the first discharge capacity was measured when the battery was charged and discharged at a voltage regulated voltage of 3.0 V to 4.5 V at a charge / discharge current density of 0.5 mA / cm ^2. The ratio (%) divided by the value is shown in Table 2. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0042]

[Example 7] L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.92 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 6: 5, stirred for 4 hours, evaporated to evaporate water, calcined at 700 ° C. for 12 hours, washed with 1 weight of the calcined product and 50 weight of water for 4 hours, and filtered. Was separated by filtration to obtain a powder, which was then vacuum dried at 100 ° C. to obtain Li _0.92 NiO ₂ . The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is A
7

The X value of the sample A7 thus synthesized,
The peak intensity of the interplanar spacing of 2.05 ± 0.02Å against the peak intensity of 4.74 ± 0.04Å, and the battery using the sample A7 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. It has a merit that it can discharge a large capacity at high voltage and can be used as a positive electrode material for high energy density batteries.

The capacity maintenance rate (discharge capacity value when the charge and discharge current density of 0.5 mA / cm ² was 3.0 V to 4.5 V, which was regulated and discharged at the first discharge capacity). The ratio (%) divided by the value is shown in Table 2. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

[0046]

[Example 8] L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.94 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water in a molar ratio of 4: 1 and stirred for 4 hours, then water was evaporated, and the mixture was calcined at 800 ° C. for 12 hours, washed with 50 parts by weight of water for 4 hours, and the filtrate was obtained. Was separated by filtration to obtain a powder, which was then vacuum dried at 100 ° C. to obtain Li _0.94 NiO ₂ . The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is A
8

The X value of the sample A8 thus synthesized,
The peak intensity of the interplanar spacing of 2.05 ± 0.02Å and the peak intensity of the interplanar spacing of 4.74 ± 0.04Å, the battery using the sample A8 as the positive electrode active material is up to 4.5 V at a current density of 0.5 mA / cm ^2. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. It has a merit that it can discharge a large capacity at high voltage and can be used as a positive electrode material for high energy density batteries.

In addition, this battery was maintained at a capacity of 3.0 V-4.5 V at a charge / discharge current density of 0.5 mA / cm ² , and the capacity retention rate (the discharge capacity value was determined as the first discharge capacity). The ratio (%) divided by the value is shown in Table 2. As is apparent from this, it is understood that the capacity decrease due to the cycle is small.

In Examples 1 to 8, starting materials, firing temperature, mixing method of lithium salt, and Li _x NiO ₂ (X ≦ 1.0) having different mixing atomic ratio Li / Ni of lithium salt and nickel salt were used as the positive electrode active material. The characteristics of the battery prepared by using the above are shown, but the starting materials, the firing temperature, the mixing method of the lithium salt, the mixed atomic ratio of the lithium salt and the nickel salt are not limited, and the lithium salt and the nickel salt are not limited. Li by atomic ratio
/Ni≧1.2, the mixture is heated and baked, and then excess lithium is washed away to obtain an X-ray diffraction analysis. The interplanar spacing is 4.74 ± for the peak intensity of 2.05 ± 0.02Å Needless to say, the same effect is produced when a complex oxide Li _x NiO ₂ (X ≦ 1.0) having a peak intensity of 0.04 Å is 1.2 times or more is used as the positive electrode active material.

[0051]

[Comparative Example 1] L synthesized as follows in the positive electrode active material
A lithium battery was produced in the same manner as in Example 1 except that i _0.87 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was mixed at a molar ratio of 1: 1 and baked at 800 ° C. for 12 hours to obtain Li _0.87 NiO ₂ . The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry.
This sample is designated as B1.

X value of the sample B1 thus synthesized,
The peak intensity of the interplanar spacing of 2.05 ± 0.02Å and the peak intensity of the interplanar spacing of 4.74 ± 0.04Å, and the battery using the sample B1 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the charge / discharge characteristics when the battery was charged and then discharged to 3.0V. Compared with this battery, the batteries produced in Examples 1 to 8 of the present invention have a large discharge capacity,
It can be seen that it shows excellent performance.

[0054]

[Comparative Example 2] L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.79 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was mixed in a molar ratio of 1: 1 and baked at 900 ° C. for 12 hours to obtain Li _0.79 NiO ₂ . The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry.
This sample is designated as B2.

The X value of the sample B2 thus synthesized,
The peak intensity of the interplanar spacing of 2.05 ± 0.02Å and the peak intensity of the interplanar spacing of 4.74 ± 0.04Å, and the battery using the sample B2 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the charge / discharge characteristics when the battery was charged and then discharged to 3.0V. Compared with this battery, the batteries produced in Examples 1 to 8 of the present invention have a large discharge capacity,
It can be seen that it shows excellent performance.

[0057]

[Comparative Example 3] L synthesized on the positive electrode active material as follows
A lithium battery was produced in the same manner as in Example 1 except that i _0.86 NiO ₂ was used.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 11:10 and stirred for 4 hours, then water was evaporated and calcined at 800 ° C.
The mixture was washed with 50 parts by weight of water for 4 hours, the filtrate was separated by filtration, and the obtained powder was vacuum dried at 100 ° C. to obtain Li _0.86 NiO ₂ . The chemical composition was calculated from the analysis value of nickel by ICP emission spectrometry and the analysis value of lithium by atomic absorption spectrometry. This sample is B3
And

The X value of the sample B3 thus synthesized,
The peak intensity of the interplanar spacing of 2.05 ± 0.02Å against the peak intensity of 4.74 ± 0.04Å, and the battery using the sample A7 as the positive electrode active material has a current density of 0.5 mA / cm ² up to 4.5 V. Table 1 shows the first charge / discharge characteristics when the battery was charged and then discharged to 3.0V. As compared with this battery, it can be seen that the batteries manufactured in Examples 1 to 8 of the present invention have a large discharge capacity and exhibit excellent performance.

FIGS. 4 and 5 show the first, fifth, sixth, seventh and eighth embodiments.
Also, the relationship between the mixed atom ratio Li / Ni of the lithium salt and the nickel salt and the first-time discharge capacity of the batteries produced in Comparative Examples 1 and 3 are shown. As is clear from this, when using a positive electrode material obtained by mixing a lithium salt and a nickel salt so that the atomic ratio Li / Ni ≧ 1.2, heating and firing, and then removing excess lithium by washing, It can be seen that the battery has a large discharge capacity and exhibits excellent performance. Also,
Comparing A1 of Example 1 and A8 of Example 8 with respect to the firing temperature, A1 of 700 ° C. is slightly superior to A8 of 800 ° C., but there is no big difference, and it is almost the same in the firing temperature range of 700 ° C. to 800 ° C. It can be seen that various characteristics are obtained.

[0061]

Comparative Example 4 A lithium battery was manufactured in the same manner as in Example 1 except that Sample B4 synthesized as follows was used as the positive electrode active material.

First, LiOH.H ₂ O and Co (NO ₃ ) ₂
6H ₂ O is dissolved in water at a molar ratio of 1: 1 and stirred for 4 hours, then water is evaporated, the obtained powder is calcined at 800 ° C. for 12 hours, and the obtained powder is vacuum dried at 100 ° C. The LiCoO ₂ obtained in step ₁ was used. This sample is designated as B4.

When the sample B4 thus synthesized was analyzed by X-ray diffraction analysis, only a peak corresponding to LiCoO ₂ was observed, and no other compound was mixed. In addition, a battery using this sample B4 as a positive electrode active material is 0.5 mA / c.
Table 1 shows the first charge / discharge characteristics when the battery was charged to 4.5 V at a current density of m ² and then discharged to 3.0 V.
As compared with this battery, it can be seen that the batteries manufactured in Examples 1 to 8 of the present invention have a large discharge capacity and exhibit excellent performance.

[0064]

Comparative Example 5 A lithium battery was produced in the same manner as in Example 1 except that Sample B5 synthesized as described below was used as the positive electrode active material.

First, LiOH.H ₂ O and Co (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 4: 1 and stirred for 4 hours, then water was evaporated, and the obtained powder was calcined at 700 ° C. for 12 hours, and 1 weight of the calcined product was heated to 50 weight of water for 4 hours. The powder obtained by washing and separating the filtrate by filtration is 100 ° C.
LiCoO ₂ obtained by vacuum-drying was used.
This sample is designated as B5.

When the sample B5 thus synthesized was analyzed by X-ray diffraction analysis, only a peak corresponding to LiCoO ₂ was observed, and no other compound was mixed. Further, a battery using this sample B5 as a positive electrode active material is 0.5 mA / c.
Table 1 shows the first charge / discharge characteristics when the battery was charged to 4.5 V at a current density of m ² and then discharged to 3.0 V.
As compared with this battery, it can be seen that the batteries manufactured in Examples 1 to 8 of the present invention have a large discharge capacity and exhibit excellent performance.

Further, unlike the case of LiNiO ₂ , it is clear that there is no tendency to improve the battery characteristics even if an excess lithium salt is added and baked.

[0068]

Comparative Example 6 A lithium battery was produced in the same manner as in Example 1 except that Sample B6 synthesized as described below was used as the positive electrode active material.

First, LiOH.H ₂ O and Ni (NO ₃ ) ₂
6H ₂ O was dissolved in water at a molar ratio of 4: 1 and stirred for 4 hours, water was evaporated, and the obtained powder was calcined at 700 ° C. for 12 hours. The powder was vacuum dried at 100 ° C. without washing. By doing so, Sample B6 was obtained.

When the sample B6 thus synthesized was analyzed by X-ray diffraction analysis, peaks attributable to Li ₂ O and Li ₂ CO ₃ were found in addition to the peak corresponding to LiNiO ₂ . When a battery using the sample B6 as the positive electrode active material was charged to 4.5 V at a current density of 0.5 mA / cm ² , a short circuit of the battery was observed during charging and it was not possible to discharge or charge thereafter. Compared with this battery,
It can be seen that the batteries produced in Examples 1 to 8 of the present invention have a large discharge capacity and exhibit excellent performance.

Further, it is clear that the work of washing and removing excess lithium is necessary to obtain excellent battery characteristics.

[0072]

[0073]

[0074]

[0075]

As described above, according to the present invention,
A lithium battery having a small size and a large charge / discharge energy can be inexpensively constructed, and it has an advantage that it can be used in various fields including a power source 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 is} an X-ray diffraction characteristic diagram of Li _0.99 NiO ₂ in Example 1 of the present invention.

FIG. 3 is a charge / discharge characteristic diagram of Li _0.99 NiO ₂ in Example 1 of the present invention.

FIG. 4 shows a mixed atom ratio Li / Ni of a lithium salt and a nickel salt and a first discharge capacity of the batteries prepared in Examples 1, 5, 6, 7, 8 of the present invention and Comparative Examples 1, 3. FIG.

FIG. 5 is a mixed atomic ratio Li of a lithium salt and a nickel salt of the batteries prepared in Example 7 of the present invention and Comparative Examples 1 and 3;
The figure which shows the relationship (enlarged view) between / Ni and the discharge capacity of the 1st time.

[Explanation of symbols]

 1 Sealing plate 2 Gasket 3 Positive electrode case 4 Lithium negative electrode 5 Separator 6 Positive electrode mixture pellet

 ─────────────────────────────────────────────────── ─── 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 (2)

[Claims] 1. A plane spacing of 2.0 ± 0.
Surface spacing for peak intensity of 02Å 4.74 ± 0.04
Double oxide Li _x N having a peak intensity of Å 1.2 times or more
iO ₂ (X ≦ 1.0) is contained as a positive electrode active material, lithium or a compound thereof is used as a negative electrode active material, it is chemically stable to the positive electrode active material and the negative electrode active material, and the lithium ion is 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 has an atomic ratio of Li / Ni ≧.
Li _x NiO ₂ (X ≦ 1.0) obtained by mixing a lithium salt and a nickel salt so as to be 1.2, heating and firing, and washing and removing excess lithium. 1. The lithium battery according to 1.