JPH10188954A - Lithium battery - Google Patents

Abstract

(57) [Summary] Li-Ni-O-based composition or Li-Ni-
When a Co—O-based composition is put into practical use, the difficulty in forming a layered structure and the problem of instability are solved, and a highly reliable lithium battery with stable charge / discharge characteristics is provided. SOLUTION: The lithium battery of the present invention comprises Li-Ni-
MO-based oxides (M has a valence other than Co of +1 to +
3) or a Li-Ni-Co-MO based oxide (M) in which the atomic ratio of Co is less than 0.5 with respect to the total atomic ratio of Ni and Co. Has a valence of +
A positive electrode 1 having a 1 to +3 oxygen coordination structure) and a negative electrode 2 capable of inserting and extracting Li ions
And a non-aqueous electrolyte 3 in which Li ions can move between the negative electrode and the positive electrode.

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 Li--Ni--O system and a Li--Ni--C system in which a part of Ni is replaced by Co.
The present invention relates to a lithium battery using an o-O-based oxide for a positive electrode.

[0002]

2. Description of the Related Art At present, commercially available lithium batteries use a composition represented by the chemical formula Li _x CoO _y as a positive electrode material. However, since Co (cobalt) has a small reserve as a resource, use of a composition containing Co causes an increase in the cost of a lithium battery. Therefore, a Li—Ni—O-based composition represented by a chemical formula Li _x NiO _{y in} which Co is entirely replaced with Ni,
And Li-Ni-Co- in which Co is partially replaced by Ni
O-based oxides are promising as low-cost materials.

Further, the positive electrode material of a lithium battery is required to have a capability of easily allowing lithium ions to enter and exit during charging and discharging, and from the viewpoint of this capability, it is desirable to have a layered structure. That is, in the case of the Li-Ni-O system, a structure in which lithium-oxygen-nickel-oxygen-lithium is stacked in the C-axis direction of the unit cell of the crystal is desirable, and (003) / ( 104) A layered structure with a diffraction intensity ratio of 1 or more (using Cu-Kα as an X-ray source) is desirable.

Hitherto, it has been difficult to obtain a layered structure of the Li—Ni—O system, and efforts have been made to obtain a desired layered structure by devising the firing atmosphere and starting materials.
The method disclosed in Japanese Patent Application Laid-Open No. Hei 2-40861 is an example. In this example, a Li-Ni-O system (LiNiO ₂ ) having good characteristics can be obtained by firing in air. In order to obtain LiNiO ₂ , it is usually necessary to fire in a sufficiently strong oxidizing atmosphere such as in oxygen. Since Co tends to have a valence of +3, a Li-Co-O-based composition having a layered structure can be easily obtained by baking in air, but one of the causes of the difficulty in obtaining a layered structure in a Li-Ni-O-based system is , And Ni are unlikely to have a +3 valence.

[0005] In addition, + trivalent Ni is inherently unstable. For this reason, the layered structure of the Li—Ni—O-based composition is unstable. According to the findings of the present inventors, for one year, Li
When the -Ni-O-based composition was left in a dry box, the (003) / (104) X-ray diffraction intensity ratio was 1.25.
From 0.56 to 0.56. This reduction is caused by Ni
If the Li-Ni-Co-O-based composition is substituted with o, the content is reduced, but sufficient stability cannot be obtained unless the substitution amount is 50 atomic percent or more.

JP-A-6-267538 discloses that the instability in the layered structure of a Li-Ni-O-based composition is caused by water resistance. As a countermeasure, silicon or boron is added in an amount of 10 atomic percent or less. It is described.

[0007] The instability of the layered structure is expressed by Li-Ni-
This is considered to be related to the stability of the charge / discharge cycle of the lithium battery manufactured using the O-based composition.

[0008]

SUMMARY OF THE INVENTION The present invention relates to Li-Ni
-O system and Li-N in which part of Ni is substituted by Co
It is an object of the present invention to provide a highly reliable lithium battery having stable charge / discharge characteristics by solving the difficulty of forming a layered structure and the problem of instability when an i-Co-O-based composition is put into practical use.

[0009]

The invention according to claim 1 is
A positive electrode having a Li-Ni-MO-based oxide (M is an element having a valence of +1 to +3 and having a six-coordinate oxygen structure other than Co), a negative electrode capable of inserting and extracting Li ions, A lithium battery including an electrolytic solution in which Li ions can move between the negative electrode and the positive electrode.

According to a second aspect of the present invention, in the lithium battery according to the first aspect, the element M is an alkali metal element or an alkaline earth metal element.

According to a third aspect of the present invention, in the lithium battery according to the second aspect, the alkali metal element is sodium, potassium, rubidium or cesium.

The invention according to claim 4 is the lithium battery according to claim 2, wherein the alkaline earth metal element is magnesium, calcium, strontium or barium.

[0013] The invention according to claim 5 is the invention according to claims 1 to 4.
Wherein the content of the element M is at least 0.001 and 0.0
It is in the range of 5 or less.

The invention according to claim 6 is the invention according to claims 1 to 5
In the lithium battery according to any one of the above, Li is in a range of 0.7 or more and 1.3 or less and O is in a range of 1.8 or more and 2.2 or less in atomic ratio with respect to Ni. Things.

According to a seventh aspect of the present invention, the atomic ratio of Co is N
Li that is less than 0.5 with respect to the total atomic ratio of i and Co
A positive electrode having a -Ni-Co-MO-based oxide (M is an element having a valence of +1 to +3 and having a six-coordinate structure of oxygen); a negative electrode capable of inserting and extracting Li ions; A lithium battery including an electrolyte solution in which Li ions can move between the positive electrode and the positive electrode.

The invention according to claim 8 is the lithium battery according to claim 7, wherein the element M is an alkali metal element or an alkaline earth metal element.

According to a ninth aspect of the present invention, in the lithium battery of the eighth aspect, the alkali metal element is sodium, potassium, rubidium or cesium.

According to a tenth aspect, in the lithium battery according to the eighth aspect, the alkaline earth metal element is magnesium, calcium, strontium, or barium.

An eleventh aspect of the present invention provides the lithium battery according to any one of the seventh to tenth aspects, wherein the element M
Is in the range of 0.001 to 0.05 in atomic ratio with respect to the total atomic ratio of Ni and Co.

According to a twelfth aspect of the present invention, in the lithium battery according to any one of the seventh to eleventh aspects, the atomic ratio of Li is 0.7 to the total atomic ratio of Ni and Co.
Or more and 1.3 or less, and O is 1.8 or more;
It is in the range of 2 or less.

[0021]

FIG. 1 is a sectional view showing an embodiment of a lithium battery according to the present invention. An embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is Li-Ni
-MO-based oxide (M has a valence other than +1 to +
3, an element which can have a six-coordinate structure of oxygen), or Li-Ni-Co- in which Ni is partially substituted with Co.
A positive electrode having an MO oxide (M is an element which can have a six-coordinate oxygen structure in the range of +1 to +3), 2 is a negative electrode for absorbing and releasing Li ions such as graphite and Li metal, and 3 is porous A non-aqueous electrolytic solution composed of a mixture of ethylene carbonate / dimethoxyethane / lithium perchlorate, etc., held on an organic film, 4 and 5 being current collectors made of aluminum foil or the like, 6 and 7 being cases made of stainless steel or the like, Reference numeral 8 denotes a gasket for sealing the cases 6 and 7, which is made of an insulating material such as rubber.

Li-Ni-MO oxide, and Li in which this Ni is substituted with Co in an atomic ratio of less than 50%
-Ni-Co-MO oxide has a valence of +1 to +
By containing the element M which can take a six-coordinate structure of oxygen in 3, the layered structure becomes stable and the charge / discharge characteristics of the lithium battery become stable.

The element having a six-coordinate structure takes in oxygen during firing and coordinates effectively in the crystal structure, so that a stable layered structure is considered to be obtained. The effect is larger when the valence is small with the valence being +3 as the threshold value.

The above-mentioned element M is selected from the group consisting of sodium, potassium, rubidium and cesium having a valence of +1 and an oxygen of 6
An alkali metal element having a coordination structure or an alkaline earth metal element having a valence of +2 and a six-coordinate oxygen structure, such as magnesium, calcium, strontium or barium, is particularly effective.

In addition, V, Cr, Fe, Mo, Rh, A
g, Cd, Ir, Al, Ga, Pb, Bi, La, M
Elements such as n, Cu, Sc, and Ti having an atomic valence of +3 or less and having a six-coordinate oxygen structure are also effective.

The content of the above-mentioned element M in the Li—Ni—MO based oxide is 0.0
It is particularly effective in the range of 01 or more and 0.05 or less.

The content of the element M in the Li—Ni—Co—MO oxide in which part of Ni in the Li—Ni—MO oxide is replaced by Co is determined by the atomic ratio of Ni to Co. With respect to the total of the range of 0.001 or more and 0.05 or less,
It is particularly effective as in the case of the Li-Ni-MO system.

Further, Li-Ni-M- containing the element M
The O-based oxide has an atomic ratio of Li to Ni of 0.7.
Or more and 1.3 or less, and O is 1.8 or more;
A particularly large effect can be obtained in the range of 2 or less.

Li-Ni-Co-M- containing element M
The O-based oxide has an atomic ratio of Li in the range of 0.7 or more and 1.3 or less with respect to the total atomic ratio of Ni and Co;
When O is in the range of 1.8 or more and 2.2 or less, Li-Ni-M
As with the -O system, a particularly great effect can be obtained.

The above-mentioned Li-Ni-MO-based oxide is prepared by adding oxygen distribution to commercially available lithium hydroxide monohydrate (LiOH.H ₂ O) and nickel hydroxide (Ni (OH) ₂ ). Such as sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ), and rubidium carbonate (Rb ₂ CO ₃ ) containing an alkali metal element such as an oxide, hydroxide or carbonate of the element M having a coordination structure ) Or cesium carbonate (Cs ₂ C)
O ₃ ), calcium hydroxide (Ca (OH) ₂ ) containing an alkaline earth metal element, magnesium hydroxide (M
g (OH) ₂ ), strontium carbonate (SrCO ₃ ), or barium oxide (BaO) are mixed in a mortar in a dry air atmosphere, and the mixed powder is calcined at 700 ° C. in air for a predetermined time to obtain a synthetic powder. be able to.

The Li-Ni-Co-MO oxide is a material used for synthesizing the above-mentioned Li-Ni-MO oxide, which is a cobalt hydroxide containing Co element (Co ( O
H) It can be obtained by adding ₃ ), firing similarly, and synthesizing.

The obtained Li-Ni-MO-based and Li-Ni-Co-MO-based oxides are obtained by using graphite as a conductive material and polyvinylidene fluoride (PVD) as a binder.
F) and a solvent such as N-methylpyrrolidone (NMP), and a predetermined amount of the paste is spread on an aluminum foil (current collector 4), dried, and then pressed to form. Thus, the positive electrode 1 can be obtained.

[0033]

Embodiments will be described below. The positive electrode 1 shown in FIG. 1 is composed of the compositions shown in Examples 1 to 8 below.

Embodiment 1 Commercially available lithium hydroxide monohydrate (LiOH.H ₂ O) and nickel hydroxide (Ni
(OH) ₂ ), sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ), rubidium carbonate (Rb ₂ CO ₃ ) or cesium carbonate (Cs ₂ C) as an alkali metal element
O ₃ ) were mixed to obtain raw materials for Samples 1 to 4 (Table 1 below). The mixing ratio is such that Li: Ni: alkali metal element = 1.05: 1: 0.05 in atomic ratio and mixed in a mortar in a dry air atmosphere. Bake at 700 ° C for 5 minutes in an electric furnace,
Samples 1 to 4 were obtained by synthesis.

[0035]

[Table 1]

For samples 1 to 4, Cu-Kα
X-ray diffraction analysis was performed using X-rays, and the ratio of the (003) plane peak (around 2θ = 18 degrees) intensity to the (104) plane peak (around 2θ = 44 degrees) intensity, (003) / (10)
4) was calculated. The results are shown in Table 2. Table 2 also shows, for comparison, the peak intensity ratio (003) / (104) of LiNiO ₂ (sample 5) containing no alkali metal element, which was obtained in the same manner as in this example. I have.

[0037]

[Table 2]

As is clear from the results shown in Table 2, the peak intensity ratio (003) / (104) is higher in Samples 1 to 4 containing the alkali metal element than in Sample 5 containing no alkali metal element. The addition of the alkali metal element promotes the development of the layered structure even when heating is performed at 700 ° C. for only 5 minutes.

Embodiment 2 FIG. Commercially available lithium hydroxide monohydrate (LiOH.H ₂ O) and nickel hydroxide (Ni
(OH) ₂ ) and sodium carbonate (Na ₂ CO ₃ ) as an alkali metal element in various proportions,
10 raw materials (Table 3 below). The mixing ratio is expressed as an atomic ratio of Li: Ni: alkali metal element = 1.05: 1: z
(Z = 0.0007, 0.001, 0.01, 0.0
5,0.07), mixed in a mortar in a dry air atmosphere, and calcined in air in an electric furnace at 700 ° C. for 5 hours to synthesize.
By pulverizing, samples 6 to 10 were obtained.

[0040]

[Table 3]

Next, using the samples 6 to 10 described above, FIG.
The positive electrode 1 shown in FIG. The positive electrode 1 was formed by 90% by weight of each of the samples 6 to 10 and graphite 6 as a conductive material.
% By weight and polyvinylidene fluoride (P
VDF) 4% by weight, N-methylpyrrolidone (NMP) was mixed as a solvent, and a paste was spread in a predetermined amount on an aluminum foil (cathode current collector 4) and dried. , And formed by pressing.

Next, the above-mentioned samples 6 to 10 were formed on the positive electrode 1, metal lithium was formed on the negative electrode 2, and ethylene carbonate / electrolyte was formed on the electrolyte.
A coin-type battery shown in FIG. 1 was constructed using a mixed solution of dimethoxyethane / lithium perchlorate, and a battery capacity test was performed.

FIG. 2 shows one result of the battery capacity test, showing the result in the case of the positive electrode using the sample 8 (z = 0.01). For comparison, the same method as in this example was used. Sample 11 containing no alkali metal element (LiN
The case of the positive electrode using iO ₂ firing time (5 hours) is also shown as a conventional example. As apparent from FIG. 2, the discharge capacity of Sample 8 to which Na was added was:
A clear increase was observed in comparison with the discharge capacity of Sample 11 to which Na was not added.

FIG. 3 shows the change in the battery discharge capacity with respect to the amount of added Na, where z = 0.001 (sample 7).
In the case of z = 0.05 (sample 9), similar to the case of z = 0.01 (sample 8) shown in FIG. 2, a result was obtained that was larger than that of sample 11 containing no alkali metal element. On the other hand, z = 0.0007 (sample 6) and z
In the case of 0.07 (sample 10), the effect of adding Na was not obtained. This result indicates that when z is less than 0.001, the effect of the added element is not sufficiently exhibited due to the small amount of addition, and when z exceeds 0.05, it is attributed to a change in the crystal structure. Conceivable. From the above results, it is optimal that the addition amount z of Na is in the range of 0.001 ≦ z ≦ 0.05.

Further, represented by Li _x NiNa _z O _y ,
In the range of 0.001 ≦ z ≦ 0.05, the same test was performed when x was not less than 1.3 and less than 0.7, and when y was not less than 2.2 and less than 1.8. ,
Conversely, the battery discharge capacity decreased. It is considered that the reason for the decrease in the above range is that the deviation from stoichiometry disrupts the crystal structure and inhibits lithium diffusion.

Further, when potassium (K ₂ CO ₃ ), rubidium (Rb ₂ CO ₃ ) and cesium (Cs ₂ CO ₃ ) are added as alkali metal elements, the same effect as when sodium is added is obtained. Was done.

Embodiment 3 FIG. Commercially available lithium hydroxide monohydrate (LiOH.H ₂ O) and nickel hydroxide (Ni
(OH) ₂ ), calcium hydroxide (Ca (OH) ₂ ) and magnesium hydroxide (M
g (OH) ₂ ), strontium carbonate (SrCO ₃ ), or barium oxide (BaO) were mixed to obtain raw materials for Samples 12, 13, 14, and 15, respectively. The mixing ratio is expressed as an atomic ratio of Li: Ni: alkaline earth metal element = 1.
05: 1: 0.05, respectively, and the mixture was mixed in a mortar in a dry air atmosphere, and the mixed powder was baked in an electric furnace at 700 ° C. for 5 minutes in air to synthesize.
After crushing, samples 12 to 15 were obtained.

For Samples 12 to 15, Cu-
X-ray diffraction analysis was performed using Kα rays, and the ratio of the (003) plane peak (around 2θ = 18 degrees) intensity to the (104) plane peak (around 2θ = 44 degrees) intensity, (003) / ( 1
04) was calculated. The results are shown in Table 4 below.

[0049]

[Table 4]

As is clear from Table 4 above, Samples 12 to 15 of the present example containing an alkaline earth metal element had a peak intensity ratio (003) in comparison with Sample 5 containing no alkaline earth metal element. ) / (104) is about 37-4
A five-fold increase, firing for only 5 minutes at 700 ° C., promotes layered structure development.

Embodiment 4 FIG. Commercially available lithium hydroxide monohydrate (LiOH.H ₂ O) and nickel hydroxide (Ni
(OH) ₂ ) and calcium hydroxide (Ca (OH) ₂ ) as an alkaline earth metal element were mixed at various ratios to obtain raw materials for Samples 16 to 20 (Table 5 below). The mixing ratio is Li: Ni: alkaline earth metal element =
1.05: 1: z (z = 0.0007, 0.001,
(0.01, 0.05, 0.07), and mixed in a mortar in a dry air atmosphere. The mixed powder was fired in an electric furnace at 700 ° C. for 5 hours in air. After the synthesis, pulverization was performed to obtain samples 16 to 20.

[0052]

[Table 5]

Next, the positive electrode 1 shown in FIG. 1 was formed using the samples 16 to 20. The positive electrode 1 was formed by separating 90% by weight of each of the samples 16 to 20, 6% by weight of graphite as a conductive material, and 4% by weight of polyvinylidene fluoride (PVDF) as a binder, and N-methylpyrrolidone (NMP). Was mixed as a solvent to form a paste, and a predetermined amount was spread on an aluminum foil (positive electrode current collector 4), dried, and then pressed.

Next, the above-mentioned samples 16 to 20,
A coin-type battery as shown in FIG. 1 was constructed using lithium metal as the negative electrode 2 and a mixed solution of ethylene carbonate / dimethoxyethane / lithium perchlorate as the electrolyte, and a battery capacity test was performed.

FIG. 4 shows one result of the battery capacity test, and shows the result in the case of the positive electrode using the sample 18 (z = 0.01). For comparison, the same method as in this example was used. Sample 11 containing no alkali metal element (Li
The case of a positive electrode using NiO ₂ firing time (5 hours) is also shown as a conventional example. As is clear from FIG. 4, the discharge capacity of Sample 18 to which Ca was added showed a clear increase as compared to the discharge capacity of Sample 11 to which Ca was not added.

FIG. 5 shows the change in the battery discharge capacity with respect to the amount of Ca added, where z = 0.001 (sample 1).
In the case of 8) and z = 0.05 (sample 19), similar to the case of z = 0.01 (sample 18) shown in FIG. 4, a result was obtained which was higher than that of sample 11 containing no alkali metal element. . On the other hand, z = 0.0007 (sample 1
6) and 0.07 (sample 20)
The effect of addition is small. This result is due to the fact that when z is less than 0.001, the effect of the added element is not sufficiently exhibited due to the small amount of addition, and when z exceeds 0.05, the crystal structure changes. It is considered to be. From the above results, the added amount z of Ca is 0.001 ≦ z ≦ 0.05.
It is optimal to set the range.

Further, represented by Li _x NiCa _y O _z ,
In the range of 0.001 ≦ z ≦ 0.05, the same test was performed when x was not less than 1.3 and less than 0.7, and when y was not less than 2.2 and less than 1.8. ,
Conversely, the battery discharge capacity decreased. It is considered that the reason for the decrease in the above range is that the deviation from stoichiometry disrupts the crystal structure and inhibits lithium diffusion.

When magnesium hydroxide (Mg (OH) ₂ ), strontium carbonate (SrCO ₃ ), or barium oxide (BaO) is added as an alkaline earth metal element, the same as when calcium hydroxide is added. The effect was obtained.

Embodiment 5 FIG. In Example 2, a part of nickel of a material (sample 8) in which the alkali metal element is sodium and the mixing ratio Z is 0.01 in terms of atomic ratio of nickel to nickel 1 is replaced with cobalt in various ratios. The prepared material was produced in the same manner as in Example 2 using cobalt hydroxide (Co (OH) ₃ ) as a cobalt source. The nickel / cobalt ratio is 0.9 / 0.1, 0.8 /
Samples of 0.2, 0.7 / 0.3, 0.6 / 0.4 were prepared and used as samples 21 to 24, respectively. Further, as comparative samples, samples in which nickel of the sample 11 containing no alkali metal was replaced with cobalt at the above ratio were prepared, and the samples were referred to as samples 25 to 28, respectively. Using these samples as the positive electrode 1, a coin battery as shown in FIG.

FIG. 6 shows one result of the battery capacity test, in which the discharge capacities of Samples 21 to 24 and Samples 25 to 28 are compared. As is apparent from FIG.
The charge / discharge capacities of Samples 21 to 24 containing a showed a clear increase as compared with those of Samples 25 to 28 not containing Na.

Embodiment 6 FIG. The sodium of sample 22 of Example 5 was replaced with another alkali metal element, potassium (K ₂ C).
O ₃ ), rubidium (Rb ₂ CO ₃ ), cesium (Cs ₂ C
O ₃ ) were prepared, and each sample 29
As Nos. 31 to 31, the same battery capacity test as in Example 5 was performed.

FIG. 7 shows the results of the battery capacity test.
9 shows a comparison between discharge capacities of Samples 26 and 31 and Sample 26. As is clear from FIG. 7, the discharge capacities of the samples 29 to 31 containing the alkali metal are clear as compared with the discharge capacities of the sample 26 not containing the alkali metal, as in the case of the sodium element (sample 22). There was an increase.

[0063] In _{addition, Li x Ni 1-n Co} n M z O y (M:
An alkali metal element, represented by 0 <n <0.5);
In the range of 001 ≦ z ≦ 0.05, x is not less than 1.3 and less than 0.7, and y is not less than 2.2 and 1.8.
The same test was carried out for the case where the value was less than the above, but the battery discharge capacity was conversely reduced. It is considered that the reason for the decrease in the above range is that the deviation from stoichiometry disrupts the crystal structure and inhibits lithium diffusion.

Embodiment 7 FIG. In the above Example 4, the alkaline earth metal element was calcium, and the mixing ratio Z was 0.01 in terms of atomic ratio with respect to nickel 1 (sample 1
A material in which part of nickel of 7) was replaced with cobalt at various ratios was produced in the same manner as in Example 4 using cobalt hydroxide (CO (OH) ₃ ) as a cobalt source. Regarding the nickel / cobalt ratio, the same as in Example 5 was used.
9 / 0.1, 0.8 / 0.2, 0.7 / 0.3, 0.6
/0.4, and samples 32-35 respectively
And In addition, as a comparative sample, the nickel of sample 11 (Z = 0) containing no alkaline earth metal was replaced with cobalt at the above ratio (sample 25 of Example 5).
To 28). Using these samples as the positive electrode 1, a coin battery as shown in FIG. 1 was produced, and the same battery capacity test as in Example 4 was performed.

FIG. 8 shows the results of the battery capacity test.
It is a comparison of the discharge capacities of Samples 2 to 35 and Samples 25 to 28. As is clear from FIG. 8, the discharge capacities of the samples 32 to 35 containing calcium showed a clear increase as compared with the discharge capacities of the samples 25 to 28 not containing calcium.

Embodiment 8 FIG. Sample 33 in Example 7 was prepared by substituting calcium for sample 33 with another alkaline earth metal element, magnesium (Mg (OH) ₂ ), strontium (SrCO ₃ ), and barium (BaO). The same battery capacity test as in Example 5 was performed.

FIG. 9 shows the results of the battery capacity test.
6 shows a comparison between the discharge capacities of Samples 26 to 38 and Sample 26. As is clear from FIG. 9, the discharge capacities of the samples 36 to 38 containing the alkali metal are clearer than those of the sample 26 not containing the alkali metal, as in the case of the calcium element (sample 33). There was an increase.

[0068] In _{addition, Li x Ni 1-n Co} n M z O y (M =
An alkaline earth metal element, represented by 0 <n <0.5),
In the range of 0.001 ≦ z ≦ 0.05, the same test was performed when x was 1.3 or more and less than 0.7, and when y was 2.2 or more and less than 1.8. ,
Conversely, the battery discharge capacity decreased. It is considered that the reason for the decrease in the above range is that the deviation from stoichiometry disrupts the crystal structure and inhibits lithium diffusion.

[0069]

According to the first aspect of the present invention, the positive electrode comprises:
Since the Li-Ni-MO-based oxide containing the element M having a valence of +1 to +3 and having a six-coordinate oxygen structure is used, the layered structure of the positive electrode becomes stable, and the charge / discharge characteristics of the lithium battery Improves and stabilizes.

According to the second, third and fourth aspects of the present invention, the alkali metal having a valence of +1 and a six-coordinate oxygen structure is added to the element M of the Li—Ni—MO based oxide contained in the positive electrode. Since a metal element or an alkaline earth metal element having a valence of +2 and having a six-coordinate oxygen structure is used, the effect of stabilizing the layer structure of the positive electrode is increased.

According to the invention of claim 5, the element M
Is not less than 0.001 in atomic ratio with respect to Ni,
Since it is in the range of 0.05 or less, a great effect is obtained on stabilization of the layer structure of the positive electrode.

According to the sixth aspect of the present invention, the Li—Ni—MO based oxide containing the element M is:
Since the atomic ratio of Li is in the range of 0.7 or more and 1.3 or less and O is in the range of 1.8 or more and 2.2 or less, a great effect is obtained on stabilization of the layer structure of the positive electrode. Can be

According to the seventh aspect of the present invention, C
The atomic ratio of o is 0.5 with respect to the total atomic ratio of Ni and Co.
And a valence of +1 to +3 and containing a Li-Ni-Co-MO-based oxide containing the element M having a six-coordinate oxygen structure, the layer structure of the positive electrode becomes stable, The charge and discharge characteristics of the lithium battery are improved and stabilized.

According to the eighth, ninth and tenth aspects of the present invention, the element M of the Li—Ni—Co—MO based oxide contained in the positive electrode has a six-coordinate structure of oxygen with a valence of +1. Since the alkali metal element to be used or the alkaline earth metal element having a valence of +2 and having a six-coordinate oxygen structure is used, the effect of stabilizing the layer structure of the positive electrode is increased.

According to the eleventh aspect, the content of the element M is in the range of 0.001 to 0.05 in atomic ratio with respect to the total atomic ratio of Ni and Co. In addition, a large effect can be obtained for stabilizing the layered structure of the positive electrode.

According to the twelfth aspect of the present invention, the Li—Ni—Co—MO based oxide containing the element M has an atomic ratio of Li with respect to the total atomic ratio of Ni and Co. 0.7
Or more and 1.3 or less, and O is 1.8 or more;
Since it is within the range of 2 or less, a great effect can be obtained for stabilizing the layered structure of the positive electrode.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a lithium battery according to one embodiment of the present invention.

FIG. 2 is a diagram comparing the discharge characteristics of a lithium battery according to one embodiment of the present invention with a conventional example.

FIG. 3 is a diagram showing the relationship between the Na content in Li-Ni-MO-based oxide and the discharge capacity in the lithium battery according to one embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between the Ca content in a Li—Ni—MO-based oxide and a discharge capacity in a lithium battery according to another embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a Ca content in a Li—Ni—MO based oxide and a discharge capacity in a lithium battery according to another embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between the Na content in the Li—Ni—Co—MO based oxide and the discharge capacity in the lithium battery according to one embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between an alkali metal-containing composition in a Li-Ni-Co-MO-based oxide and a discharge capacity in a lithium battery according to one embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a Ca content in a Li—Ni—Co—MO based oxide and a discharge capacity in a lithium battery according to another embodiment of the present invention.

FIG. 9 is a view showing a relationship between an alkali metal-containing composition in a Li-Ni-Co-MO-based oxide and a discharge capacity in a lithium battery according to another embodiment of the present invention.

[Explanation of symbols]

1 positive electrode, 2 negative electrode, 3 non-aqueous electrolyte, 4,5 current collector,
6, 7 cases, 8 gaskets.

Claims (12)

[Claims] 1. A Li—Ni—MO based oxide (M is C
a positive electrode having a valence of +1 to +3 and having a six-coordinate oxygen structure except o), a negative electrode capable of occluding and releasing Li ions, and movement of Li ions between the negative electrode and the positive electrode. A lithium battery comprising a possible electrolyte. 2. The lithium battery according to claim 1, wherein the element M is an alkali metal element or an alkaline earth metal element. 3. The lithium battery according to claim 2, wherein the alkali metal element is sodium, potassium, rubidium, or cesium. 4. The lithium battery according to claim 2, wherein the alkaline earth metal element is magnesium, calcium, strontium or barium. 5. The lithium battery according to claim 1, wherein the content of the element M is in the range of 0.001 to 0.05 in atomic ratio with respect to Ni. . 6. An atomic ratio of Li to Ni is 0.7.
Or more and 1.3 or less, and O is 1.8 or more;
6. The method according to claim 1, wherein the distance is in the range of 2 or less.
A lithium battery according to any of the preceding claims. 7. Li-Ni-Co-MO, wherein the atomic ratio of Co is less than 0.5 with respect to the total atomic ratio of Ni and Co.
A positive electrode having a system oxide (M is an element having a valence of +1 to +3 and having a six-coordinate structure of oxygen), a negative electrode capable of inserting and extracting Li ions, and between the negative electrode and the positive electrode,
A lithium battery comprising: an electrolyte capable of moving Li ions. 8. The lithium battery according to claim 7, wherein the element M is an alkali metal element or an alkaline earth metal element. 9. The lithium battery according to claim 8, wherein the alkali metal element is sodium, potassium, rubidium, or cesium. 10. The lithium battery according to claim 8, wherein the alkaline earth metal element is magnesium, calcium, strontium or barium. 11. The content of the element M is 0.001 or more and 0.05 or more in atomic ratio with respect to the total atomic ratio of Ni and Co.
11. The following range:
The lithium battery according to any one of the above. 12. With respect to the total atomic ratio of Ni and Co,
The atomic ratio of Li is in the range of 0.7 or more and 1.3 or less, and O is in the range of 1.8 or more and 2.2 or less. The lithium battery as described.