JP2001273896A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery capable of improving safety and reducing generation of gas without impairing battery characteristics including cycle performance. SOLUTION: In a nonaqueous electrolyte battery wherein a positive electrode 5 including a positive active material, a negative electrode 6, and a nonaqueous electrolyte containing a lithium salt are put in a casing, the positive active material is a lithium-containing composite oxide represented by the formula CoxMyAlzO2 [M is at least one kind selected from among transition metal elements and the elements in groups IIA, IIIB, IVB, and VB of the periodic table (excluding Al); 0.90<=x<1 (particularly, 0.94<=x<1); 0<y<=0.05 (particularly, 0.00001<=y<=0.05); 0<z<=0.05 (particularly, 0.0001<=z<=0.05); and x+y+z=1].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonaqueous electrolyte battery in which a positive electrode containing a positive electrode active material, a negative electrode, and a nonaqueous electrolyte containing a lithium salt are housed in a package.

[0002]

2. Description of the Related Art In recent years, there has been a demand for the development of a small, lightweight and high energy density battery as a power source for portable equipment. Non-aqueous electrolyte batteries utilizing lithium oxidation and reduction have come to be used.

[0003] In such a battery, lithium cobalt oxide is mainly used as a positive electrode material. However, charge and discharge capacity and charge and discharge efficiency gradually decrease by repeating charge and discharge, and a sufficient cycle life cannot be obtained. There is a disadvantage that. The cause of the decrease in charge / discharge capacity and charge / discharge efficiency is due to a change in the crystal structure of the positive electrode active material,
It is conceivable that the irreversible change of the active material occurs partially, and that the electrolytic solution is decomposed by charging in which the potential of the positive electrode becomes higher than the reference value or charging in which the potential becomes lower than the reference value. For this reason, as described below, attempts have been made to solve the above problem by partially substituting various metal elements in the positive electrode active material.

For example, as disclosed in Japanese Patent Application Laid-Open Nos. 4-329267 and 5-13082, a solid solution of a titanium compound in lithium cobalt oxide is used as a positive electrode active material. No. 319260 discloses a solid solution of zirconium in lithium cobaltate used as a positive electrode active material. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. A battery using a solid solution of boron or the like as a positive electrode active material has been proposed. In a battery using such a positive electrode active material, the cycle characteristics can be improved by substituting another metal element with lithium cobalt oxide as a partial element. However, there are problems such as a decrease in safety due to a decrease in the heat generation starting temperature and a significant increase in gas generation due to a reaction with the electrolyte.

[0005] In recent years, as the thickness of batteries and the improvement of energy density are rapidly progressing along with the miniaturization of portable devices,
An ion battery and a gel-like polymer battery using a laminate casing as the casing have been proposed. Such a battery is deformed by a slight increase in battery internal pressure, and thus, in addition to battery performance, battery swelling due to generation of a large amount of gas during charge / discharge or high-temperature storage is a major problem. Therefore, in order to prevent the battery from swelling, it has been necessary to develop a technique for reducing gas generation.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to improve safety and reduce gas generation without deteriorating battery characteristics such as cycle characteristics. The purpose of the present invention is to provide a non-aqueous electrolyte battery that can be used.

[0007]

Means for Solving the Problems To achieve the above object, among the present invention, the invention according to claim 1 comprises a positive electrode containing a positive electrode active material, a negative electrode, and a nonaqueous electrolyte containing a lithium salt. the storage the nonaqueous electrolyte battery outer casing, as the positive electrode active _{material, LiCo x M y Al z O} 2 [M is a transition metal element and the periodic table IIA, IIIB, IVB, VB group elements (However, Al At least one selected from the group consisting of 0.90 ≦ x <1 (in particular, 0.94 ≦ x <
1), 0 <y ≦ 0.05 (especially, 0.00001 ≦ y ≦
0.05), 0 <z ≦ 0.05 (especially 0.0001 ≦
z ≦ 0.05), and a lithium-containing composite oxide represented by x + y + z = 1] is used.

As described above, when a solid solution of lithium metal oxide and another metal element M and Al is used as the positive electrode active material, the lithium cobalt oxide has the same characteristics as lithium metal oxide in the battery characteristics such as cycle characteristics. that a solid solution of M only (specifically, LiCo _x M _y O represented by ₂₎ it can obtain the same performance as that of the positive electrode active material, moreover, other lithium cobaltate As compared to the case where a solid solution of only the metal element M is used as the positive electrode active material, safety can be improved and gas generation can be reduced. In particular, in the _{LiCo x M y Al z O 2} , 0.9
4 ≦ x <1, 0.00001 ≦ y ≦ 0.05, 0.00
In the range of 01 ≦ z ≦ 0.05, the above effect is further exhibited.

[0009] Incidentally, in the _{LiCo x M y Al z O 2} ,
The reason for restricting to 0.90 ≦ x, y ≦ 0.05 and z ≦ 0.05 is that if the amount of M or Al is too large, the amount of Co becomes relatively small, and the battery capacity decreases. It is.
On the other hand, in _{LiCo x M y Al z O 2} , particularly preferred range of y and z, 0.00001 ≦ y, 0.000
The reason for 1 ≦ z is that if the amount of M or Al is smaller than this, improvement in safety and reduction of gas generation may not be sufficiently exhibited.

[0010] According to a second aspect of the invention, in the invention according to the first aspect, the LiCo _x M _y Al _z O ₂ in M
Is at least one selected from Ti, Nb, and Zr.

When a material obtained by dissolving only another metal element M in lithium cobalt oxide is used as a positive electrode active material, if M is Ti, Nb or Zr, M is an element other than these elements. As compared with the case, the battery characteristics such as cycle characteristics are remarkably improved, but, on the other hand, safety is reduced and moreover, gas generation due to reaction with the electrolyte is caused. Therefore, when a material obtained by dissolving not only Ti, Nb, or Zr but also Al in lithium cobalt oxide is used as the positive electrode active material, it is equivalent to a solution in which only the other metal element M is dissolved in lithium cobalt oxide. While maintaining the battery characteristics described above, safety can be improved and gas generation can be reduced.

The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the electrolyte is a gel-like solid polymer.

In the case where a gel-like solid polymer is used as an electrolyte, if not only the other metal element M but also Al is dissolved in lithium cobaltate, the oxidation resistance of the gel-like solid polymer is increased. In particular, battery characteristics such as cycle characteristics and safety are improved, and gas generation due to reaction with the electrolyte can be significantly suppressed.

[0014] The invention described in claim 4 is based on claim 1,
In the invention described in the item 2 or 3, the exterior body that is deformed by a slight increase in battery internal pressure is used as the exterior body.

In a battery using such a soft laminate outer package, rupture or leakage due to deformation of the battery is liable to occur, but rupture or leakage can be suppressed if the amount of generated gas is significantly reduced as described above. .

[0016] Further, the invention according to claim 5 is based on claim 1,
In the invention described in 2, 3, or 4, an aluminum laminate exterior body is used as the exterior body that is deformed by the slight increase in battery internal pressure.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First and second embodiments of the present invention will be described below.

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a front view of a nonaqueous electrolyte battery according to a first embodiment, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, and FIG.
FIG. 4 is a cross-sectional view of a laminate exterior body used for the nonaqueous electrolyte battery according to the first embodiment. FIG. 4 is a perspective view of a power generating element used for the nonaqueous electrolyte battery according to the first embodiment.

As shown in FIG. 2, the thin battery of the present invention
The power generation element 1 includes a power generation element 1 inside the storage space 2.
Are located in This storage space 2 is, as shown in FIG.
Then, the upper and lower ends and the center of the aluminum laminate
By sealing with sealing parts 4a, 4b, 4c respectively
Is done. The storage space 2 contains ethylene carbonate.
(EC) and diethyl carbonate (DEC)
Lithium hexafluorophosphate (LiPF)₆)
An electrolytic solution dissolved at a rate of 1 mol / l is injected.
In addition, as shown in FIG.
_xM_yAl_zO _Two[M is a transition metal element and periodic table II
A, IIIB, IVB, VB group element (excluding Al)
At least one selected from the group consisting of 0.90 ≦ x <
1, 0 <y ≦ 0.05, 0 <z ≦ 0.05, x + y + z
= 1] as an active material, and a graphite-based carbon material as an active material.
Negative electrode 6 and a separator for separating these two electrodes
(Not shown in FIG. 4) in a flat spiral shape
It is produced by doing.

As shown in FIG. 3, the specific structure of the aluminum laminate case 3 is as follows.
(Thickness: 30 μm), resin layers 13 and 13 (thickness: 3) made of polypropylene via adhesive layers 12 and 12 (thickness: 5 μm) made of modified polypropylene, respectively.
0 μm) is the structure to be bonded.

The positive electrode 5 is connected to a positive electrode lead 7 made of aluminum, and the negative electrode 6 is connected to a negative electrode lead 8 made of copper, so that chemical energy generated inside the battery can be taken out as electric energy. Has become.

Here, the battery having the above structure was manufactured as follows.

First, lithium carbonate, cobalt oxide powder, aluminum oxide, and M [M is a transition metal element and an element of the periodic table IIA, IIIB, IVB, VB group (however, Al
) Is mixed with a metal oxide or hydroxide at a predetermined ratio, and calcined in an oxygen atmosphere for 24 hours (850 ° C.)
_{By, LiCo x M y Al z O} 2 (0.90
≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05) to obtain a positive electrode active material composed of a lithium-containing composite oxide. The positive electrode active material thus synthesized and graphite, carbon black, and a fluororesin-based binder were added in a weight ratio of 9%.
After mixing at a ratio of 0: 3: 2: 5 to prepare a positive electrode mixture, the positive electrode mixture was applied to both sides of an aluminum foil, dried, and then rolled, whereby a positive electrode 5 was prepared.

On the other hand, a graphite-based carbon material and a fluororesin-based binder were mixed at a weight ratio of 90:10 to prepare a negative electrode mixture, and this negative electrode mixture was applied to both surfaces of a copper foil. Then, after drying and rolling, the negative electrode 6 was produced.

Next, the positive and negative electrodes 5.
6, a positive electrode lead 7 or a negative electrode lead 8 is attached thereto, and the positive and negative electrodes 5 and 6 are spirally wound through a separator to produce a power generating element 1. Inserted in. Finally, an electrolytic solution was injected into the aluminum laminate exterior body 3, and the aluminum laminate exterior body 3 was further sealed to produce a battery. In addition, as an electrolytic solution, ethylene carbonate (E
A solution prepared by dissolving lithium hexafluorophosphate (LiPF ₆ ) at a ratio of 1 mol / l in an equal volume mixed solvent of C) and diethyl carbonate (DEC) was used.

(Second Embodiment) A battery was manufactured in the same manner as in the first embodiment except that a gel-like solid polymer was used as an electrolyte. Specifically, it is as follows.

First, after the power generating element produced in the same manner as described above is inserted into the aluminum laminate outer casing, polyethylene glycol diacrylate (molecular weight: 1000) as a prepolymer and E
1 mole of LiPF ₆ in an equal volume mixed solvent of C and DEC
and a mixture obtained by adding 5,000 ppm of t-hexyl peroxypivalate as a polymerization initiator to the mixture.
1 was injected. Thereafter, the battery was prepared by heat treatment at 60 ° C. for 3 hours and curing.

In the above embodiment, only one kind of metal is used as M. However, the present invention is not limited to this, and two or more kinds of metal (for example, Ti and Nb) are used as M. Can also obtain the effect of the present invention.

Although an aluminum laminate case is illustrated as an example of the case that is deformed by a slight increase in battery internal pressure, the present invention is not limited to such a case.

Further, as the negative electrode material used in the present invention, in addition to the above-mentioned carbon materials, lithium metal, lithium alloy and the like are preferably used. Further, the solvent of the electrolytic solution is not limited to the above, and for example, ethylene carbonate and dimethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolan, 2-methoxytetrahydrofuran, diethyl ether and the like A solvent obtained by mixing a low-viscosity low-boiling solvent with an appropriate ratio can be used. As the solute of the electrolyte solution, addition of the LiPF _6, LiN (SO ₂ C
_{2 F 5) 2, LiAsF 6} , LiClO 4, LiB
F ₄ , LiCF ₃ SO ₃ or the like can be used.

In addition, in addition to polyethylene glycol diacrylate, polyether-based solid polymers, polycarbonate-based solid polymers, polyacrylonitrile-based solid polymers, and two or more of these gel-like solid polymers can be used. Or a cross-linked polymer material,
It is also possible to use a combination of a fluorine-based solid polymer such as polyvinylidene fluoride, a lithium salt, and an electrolytic solution.

[0033]

EXAMPLES (First Example) [Examples 1 to 5] M [M is a transition metal element and periodic table II.
A, IIIB, IVB, VB Group elements (except, Al is excluded)] using Ti as, and LiCo _x M _y Al _z O
X in _2, y, z and 0.90 ≦ x <1,0 <y ≦
0.05, 0 <z ≦ 0.05
A battery was produced in the same manner as in the embodiment.

The batteries thus manufactured are hereinafter referred to as batteries A1 to A5 of the present invention, respectively.

Further, a test battery was prepared by immersing the same positive electrode as the above battery and a negative electrode (reference electrode) made of a metallic lithium foil in the same electrolytic solution as the above battery.

The batteries manufactured in this manner are hereinafter referred to as batteries A101 to A105 of the present invention, respectively. [Examples 6 to 10] Using Nb as M and LiCo
_x M _y Al _{z x} in O _2, y, z and 0.90 ≦ x <
A battery was manufactured in the same manner as the method described in the first embodiment, except that 1, 0 <y ≦ 0.05 and 0 <z ≦ 0.05.

The batteries fabricated in this manner are hereinafter referred to as Batteries A6 to A10 of the present invention, respectively.

Also, a test battery was prepared by immersing the same positive electrode as the above-mentioned battery and a negative electrode (reference electrode) made of metallic lithium foil in the same electrolytic solution as the above-mentioned battery.

The batteries fabricated in this manner are hereinafter referred to as Batteries A106 to A100 of the invention, respectively. [Examples 11 to 15] Using Pb as M and LiC
o _x M _y Al _{z x} in O _2, y, z and 0.90 ≦ x
<1, 0 <y ≦ 0.05 and 0 <z ≦ 0.05 were manufactured in the same manner as in the first embodiment, except that the battery was manufactured.

The batteries manufactured in this manner are hereinafter referred to as batteries A11 to A15 of the present invention, respectively.

Further, the same positive electrode as the above battery and a negative electrode (reference electrode) made of a metallic lithium foil were immersed in the same electrolytic solution as the above battery to prepare a test battery.

The batteries fabricated in this manner are hereinafter referred to as Batteries A111 to A115 of the invention, respectively. [Examples 16 to 20] Zn was used as M and LiC was used.
o _x M _y Al _{z x} in O _2, y, z and 0.90 ≦ x
<1, 0 <y ≦ 0.05 and 0 <z ≦ 0.05 were manufactured in the same manner as in the first embodiment, except that the battery was manufactured.

The batteries fabricated in this manner are hereinafter referred to as Batteries A16 to A20 of the present invention, respectively.

Further, a test battery was prepared by immersing the same positive electrode as the above-mentioned battery and a negative electrode (reference electrode) made of metallic lithium foil in the same electrolytic solution as the above-mentioned battery.

The batteries fabricated in this manner are hereinafter referred to as Batteries A116 to A120 of the invention, respectively. Example 21 Using Zr as M and LiCo _x M
_y Al _z x in O _2, y, and z x = 0.98, y =
A battery was manufactured in the same manner as in the first embodiment, except that 0.01 and z = 0.01.

The battery fabricated in this manner is hereinafter referred to as Battery A21 of the invention.

Also, a test battery was prepared by immersing the same positive electrode as the above battery and a negative electrode (reference electrode) made of a metallic lithium foil in the same electrolytic solution as the above battery.

The battery fabricated in this manner is hereinafter referred to as Battery A121 of the invention. Comparative Examples 1 and 2] LiCo _x M _y Al _z O ₂ in the x, y, and z, respectively x = 0.8, y = 0.1, z =
A battery was fabricated in the same manner as in Example 1 except that 0.1, x = 0.99, y = 0.01, and z = 0.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X1 and X2, respectively.

A test battery was prepared by immersing the same positive electrode as the above battery and a negative electrode (reference electrode) made of metallic lithium foil in the same electrolytic solution as the above battery.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X101 and X102, respectively. Comparative Examples 3 and 4] LiCo _x M _y Al _{z x} in O _2, y, and z x = 0.8, y = 0.1 , z = 0.1 and x = 0.99,, y = 0 A battery was fabricated in the same manner as in Example 6 except that the values were 0.01 and z = 0.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X3 and X4, respectively.

Further, a test battery was prepared by immersing the same positive electrode as the above battery and a negative electrode (reference electrode) made of a metallic lithium foil in the same electrolytic solution as the above battery.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X103 and X104, respectively. Comparative Examples 5 and 6] LiCo _x M _y Al _{z x} in O _2, y, and z x = 0.8, y = 0.1 , z = 0.1 and x = 0.99,, y = 0 A battery was manufactured in the same manner as in Example 11 except that 0.01 and z = 0.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X5 and X6, respectively.

Also, a test battery was prepared by immersing the same positive electrode as the above battery and a negative electrode (reference electrode) made of metallic lithium foil in the same electrolytic solution as the above battery.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X105 and X106, respectively. Comparative Examples 7 and 8] LiCo _x M _y Al _{z x} in O _2, y, and z x = 0.8, y = 0.1 , z = 0.1 and x = 0.99,, y = 0 A battery was fabricated in the same manner as in Example 16 except that 0.01 and z = 0.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X7 and X8, respectively.

A test battery was prepared by immersing the same positive electrode as the above battery and a negative electrode (reference electrode) made of metallic lithium foil in the same electrolytic solution as the above battery.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries X107 and X108, respectively. Comparative Example 9] LiCo _x M _y Al _{z x} in O _2,
A battery was fabricated in the same manner as in Example 1 except that y and z were x = 1, y = 0, and z = 0.

The battery fabricated in this manner is hereinafter referred to as Comparative Battery X9.

Further, the same positive electrode as the above-mentioned battery and a negative electrode (reference electrode) made of metallic lithium foil were immersed in the same electrolytic solution as the above-mentioned battery to prepare a test battery.

The battery fabricated in this manner is hereinafter referred to as Comparative Battery X109. Comparative Example 10] LiCo _x M _y Al _{z x} in O _2,
A battery was fabricated in the same manner as in Example 21 except that y and z were set to x = 0.99, y = 0.01, and z = 0.

The battery fabricated in this manner is hereinafter referred to as Comparative Battery X10.

A test battery was prepared by immersing the same positive electrode as the above battery and a negative electrode (reference electrode) made of a metallic lithium foil in the same electrolytic solution as the above battery.

The battery fabricated in this manner is hereinafter referred to as Comparative Battery X110. [Experiment 1] Using the batteries A101 to A120 of the present invention and the comparative batteries X101 to X109, the charge capacity per unit weight of the positive electrode active material was examined.
The results are shown in Tables 1 and 2.

[0067]

[Table 1]

[0068]

[Table 2] As is apparent from Table 1 and Table 2, LiCo _x M _y
As the sum of the values of y and z in Al _z O ₂ (x + y + z = 1) increases, it is recognized that the charge capacity per unit weight decreases, and as a result, the weight energy density also decreases. This is considered to be due to the fact that as the sum of the y and z values increases, the Co amount decreases.

[0069] Therefore, from the viewpoint of weight energy density, x in the _{LiCo x M y Al z O 2} , y, z
Are 0.9 ≦ x, y ≦ 0.05, z ≦ 0.05 (particularly,
0.94 ≦ x, y ≦ 0.05, z ≦ 0.05). [Experiment 2] Batteries A1 to A20 of the present invention and comparative battery X
Using 1 to X9, the cycle characteristics, high-temperature storage characteristics, and safety were examined under the following conditions, and the results are shown in Tables 1 and 2 above. -Cycle characteristics After charging until the end-of-charge voltage reaches 4.2 V at a charge current of 500 mA, the end-of-discharge voltage becomes 3.1 V at a discharge current of 500 mA.
The battery was charged and discharged for 500 cycles under the condition that the battery was discharged to the maximum. Then, the initial discharge capacity, the discharge capacity after 500 cycles, and the remaining capacity rate [discharge capacity after 500 cycles /
Initial discharge capacity × 100 (%)]. -High-temperature storage characteristics After each battery was stored at 80 ° C for 96 hours, the amount of gas generated in the batteries was examined.・ Safety 5 mg of the positive electrode active material charged to 4.2 V and 2 mg of EC (ethylene carbonate) are sealed in a predetermined container and DS
C was measured, and the heat generation starting temperature and the heat generation amount were examined.

As is clear from Tables 1 and 2, the comparative battery X in which another element M was dissolved in lithium cobaltate was dissolved.
1, X3, X5, and X7 have improved cycle characteristics as compared with the comparative battery X9 in which the other element M is not dissolved in lithium cobalt oxide, and have low-temperature characteristics not shown in Tables 1 and 2. also improved battery characteristics (in particular, LiCo _x M _y
When the value of y in O ₂ is y ≧ 0.00001). However, the comparative batteries X1, X3, X5, and X7 are comparative batteries X
As compared with No. 9, the amount of gas after high-temperature storage was large, the heat generation starting temperature was low, and the amount of heat generation was large.

On the other hand, the batteries A1 to A of the present invention in which not only the other element M but also Al was dissolved in lithium cobaltate as a solid solution.
20 has substantially the same cycle characteristics as the comparative battery X9, and has a smaller amount of gas after high-temperature storage, a higher heat generation start temperature, and a lower calorific value than the comparative batteries X1, X3, X5, and X7. it is recognized that safety is improved because less (in particular, when the value of z in LiCo _x M _y Al _z O ₂ is z ≧ 0.0001).

From the results of Experiments 1 and 2, Li
Co _x M _y Al _{z x} in O _2, y, z is 0.90 ≦
When x <1, 0 <y ≦ 0.05, and 0 <z ≦ 0.05, while suppressing the deterioration of the positive electrode capacity and the cycle characteristics,
It is possible to reduce the amount of gas during high-temperature storage and the like, and to improve safety. In particular, 0.94 ≦ x <1, 0.00
If the range is 001 ≦ y ≦ 0.05 and 0.0001 ≦ z ≦ 0.05, the above effect is further exhibited. [Experiment 3] Battery A121 of the present invention and Comparative Battery X11
0, the charge capacity per unit weight of the positive electrode active material was examined, and the cycle characteristics, high-temperature storage characteristics, and safety were examined using the battery A21 of the present invention and the comparative battery X10. And Table 3 below. The conditions for cycle characteristics, high-temperature storage characteristics and safety are as follows:
The conditions were the same as in Experiment 2 above, and in Table 2,
Inventive batteries A3, A103, A8, A108, A13,
A113, A18, A118 and comparative batteries X1, X10
1, X3, X103, X5, X105, X7, X107
The results are also shown.

[0073]

[Table 3] As is clear from Table 3, a comparative battery X in which another element M (Ti, Nb, or Zr) was dissolved in lithium cobalt oxide as a solid solution
1, X3 and X10 represent other elements M in lithium cobalt oxide.
Compared with the comparative batteries X5 and X7 in which (Pb or Zn) is dissolved, cycle characteristics are improved, and battery characteristics such as low-temperature characteristics not shown in Table 3 are also improved. On the other hand, the comparative batteries X1, X3, and X10 have a larger amount of gas after high-temperature storage than the comparative batteries X5 and X7. Is recognized.

On the other hand, in the batteries A3, A8 and A21 of the present invention in which not only the other element M (Ti, Nb or Zr) but also Al was dissolved in lithium cobaltate, the comparative battery X
1, X3, and X10, have substantially the same cycle characteristics as those of Comparative batteries X1, X3, and X10, have a significantly smaller amount of gas after high-temperature storage, have a significantly higher heat generation start temperature, and have a higher heat generation value. It is recognized that the safety has been dramatically improved because the number of particles is extremely small. Therefore, LiCo _x M
The effect of dissolving the other element M in _y O ₂ to reduce the amount of gas after high-temperature storage and improving the safety is as follows.
It can be understood that this is remarkable when Ti, Nb, or Zr is used.

(Second Example) [Examples 1 to 21] The batteries shown in Examples 1 to 20 were manufactured by the same method as that described in the second embodiment. Note that M
[M is a transition metal element and periodic table IIA, IIIB, IVB,
VB group elements (excluding Al)] and Li
The value of Co _x M _y Al _{z x} in O _2, y, z corresponds to Examples 1-21 in the first embodiment (e.g., Example 1 of the second embodiment is the first embodiment Example 1 and the type of M and the values of x, y, and z are the same).

The batteries fabricated in this manner are hereinafter referred to as Batteries B1 to B21 of the present invention, respectively. Comparative Example 1-9] kind of M, and LiCo _x M _y Al _z
The values of x, y, and z in O ₂ correspond to Comparative Examples 1 to 9 in the first embodiment (for example, Comparative Example 1 in the second embodiment differs from Comparative Example 1 in the first embodiment in the type of M). And x, y,
A battery was fabricated in the same manner as in Example 1 except that the value of z was the same.

The batteries fabricated in this manner are hereinafter referred to as comparative batteries Y1 to Y9, respectively. [Experiment 1] Batteries B1 to B20 of the present invention and comparative battery Y
The cycle characteristics, high-temperature storage characteristics and safety were examined using 1 to Y9, and the results are shown in Tables 4 and 5 below. The cycle characteristics and the high-temperature storage characteristics were performed under the same conditions as in Experiment 2 of the first embodiment, and the safety was performed under the following conditions. -Safety 5 mg of the positive electrode active material charged to 4.2 V and 2 mg of the gel polymer electrolyte were sealed in a predetermined container, and DSC measurement was performed to examine the heat generation start temperature and the heat generation amount.

[0078]

[Table 4]

[0079]

[Table 5] As is clear from Tables 4 and 5, the comparative batteries Y1, Y3, and Y obtained by dissolving another element M in lithium cobalt oxide were dissolved.
5 and Y7 have improved cycle characteristics as compared with the comparative battery Y9 in which the other element M is not dissolved in lithium cobaltate, and also have battery characteristics such as low-temperature characteristics not shown in Tables 4 and 5. improved (especially, when the value of y in the LiCo _x M _y O ₂ is y ≧ 0.00001). However, the comparative batteries Y1, Y3, Y5, and Y7 have a larger amount of gas after high-temperature storage than the comparative battery Y9, and have a lower heat generation start temperature and a larger calorific value, so that the safety is reduced. Can be

On the other hand, the batteries B1 to B of the present invention in which not only the other element M but also Al was dissolved in lithium cobaltate as a solid solution.
20 has cycle characteristics substantially equivalent to those of the comparative batteries Y1, Y3, Y5, and Y7, and furthermore, the comparative batteries Y1, Y3, and Y7.
5, Y7 compared to, small amount of gas after high temperature storage is recognized that safety is improved because more heat generation initiation temperature is high and heat generation amount is small (particularly, LiCo _x M _y A
When the value of z in l _z O ₂ is z ≧ 0.0001).

On the other hand, although not shown in Tables 4 and 5, the battery using the gel polymer
_{x M y Al z O 2 (} x + y + z = 1) in the y, according to the total value of z is greater (the value of x decreases), it is recognized that the charge capacity per unit weight is reduced, As a result, the weight energy density was found to decrease. Therefore, from the viewpoint of the weight energy density, LiCo _x M _y Al _{z x} in O _2, y, z is, 0.9 ≦ x, y ≦ 0.05 , z ≦ 0.0
5 (especially 0.94 ≦ x, y ≦ 0.05, z ≦ 0.0
It is understood that 5) is desirable.

[0082] As described above, from the results of the experiment 1, LiCo _x M _y
X, y, and z in Al _z O ₂ are 0.90 ≦ x <1, 0
Within the ranges of <y ≦ 0.05 and 0 <z ≦ 0.05, it is possible to reduce the amount of gas at the time of high-temperature storage and to improve the safety while suppressing the deterioration of the positive electrode capacity and the cycle characteristics. Can be. In particular, 0.94 ≦ x <1, 0.00001 ≦ y
Within the ranges of ≦ 0.05 and 0.0001 ≦ z ≦ 0.05, the above effects are further exhibited.

In addition, the batteries A1 to A1 of the present invention using the electrolytic solution
Compared with A21, the batteries B1 to B21 of the present invention using the gel polymer electrolyte further reduced the amount of gas generated after high-temperature storage (for example, the battery A1 of the present invention using the electrolytic solution).
Is 3.8 mg, whereas that of the battery B1 of the present invention using the gel polymer electrolyte is 3.0 mg). Therefore, when the present invention is applied to a battery using a gel polymer electrolyte, the effect is further exhibited. [Experiment 2] The cycle characteristics, high-temperature storage characteristics, and safety were examined using the battery B21 of the present invention and the comparative battery Y10. The results are shown in Table 6 below. The cycle characteristics, high-temperature storage characteristics, and safety conditions were the same as those in Experiment 1. In Table 6, the batteries B3, B8, B13, and B18 of the present invention and the comparative batteries Y1 and Y
3, Y5, and Y7 are also shown.

[0084]

[Table 6] As is clear from Table 6, the comparative battery Y in which another element M (Ti, Nb, or Zr) was dissolved in lithium cobalt oxide was dissolved.
1, Y3 and Y10 are other elements M in lithium cobalt oxide.
Compared with the comparative batteries Y5 and Y7 in which (Pb or Zn) is dissolved, cycle characteristics are improved, and battery characteristics such as low-temperature characteristics not shown in Table 6 are also improved. On the other hand, the comparative batteries Y1, Y3, and Y10 have a larger amount of gas after high-temperature storage than the comparative batteries Y5 and Y7. Is recognized.

On the other hand, in the batteries B3, B8, and B21 of the present invention in which not only the other element M (Ti, Nb, or Zr) but also Al was dissolved in lithium cobalt oxide, the comparative battery Y
1, Y3, and Y10, have substantially the same cycle characteristics, and have a significantly smaller amount of gas after high-temperature storage than the comparative batteries Y1, Y3, and Y10. It is recognized that the safety has been dramatically improved because the number of particles is extremely small. Accordingly, even in a battery using a gel polymer electrolyte, LiCo _x M _y O ₂
The effect of improving the safety by reducing the amount of gas after high-temperature storage by dissolving another element M in a solid solution is remarkable when Ti, Nb, or Zr is used as the other element M. I understand.

[0086]

As described above, according to the present invention,
There is an excellent effect that safety can be improved and the amount of gas generated can be reduced without lowering battery characteristics such as cycle characteristics. In particular, in a battery using an aluminum laminate exterior body, deformation and rupture of the exterior body can be suppressed by reducing the amount of gas generated, so that the effect is large.

[Brief description of the drawings]

FIG. 1 is a front view of a nonaqueous electrolyte battery according to a first embodiment.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a cross-sectional view of a laminate exterior body used for the nonaqueous electrolyte battery according to the first embodiment.

FIG. 4 is a perspective view of a power generation element used in the nonaqueous electrolyte battery according to the first embodiment.

[Explanation of symbols]

 1: Power generation element 2: Storage space 3: Laminated exterior body 5: Positive electrode 6: Negative electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H011 AA01 AA13 CC02 CC06 CC10 5H029 AJ11 AJ12 AK03 AL07 AM00 AM03 AM04 AM07 AM16 BJ04 BJ14 DJ02 DJ09 EJ01 EJ12 HJ02 5H050 AA14 AA15 BA17 CA08 CB08 DA02 DA13 DA14

Claims (5)

[Claims] [1 claim: a positive electrode including a positive active material, a negative electrode, the nonaqueous electrolyte battery and a non-aqueous electrolyte is housed in the outer package containing a lithium salt, as the positive electrode active material, LiCo _x M _y Al _z O ₂ [M
Is the transition metal element and the periodic table IIA, IIIB, IVB, VB
And at least one element selected from group III elements (excluding Al), and 0.90 ≦ x <1 (particularly 0.94 ≦ x
<1), 0 <y ≦ 0.05 (especially, 0.00001 ≦ y
≦ 0.05), 0 <z ≦ 0.05 (especially 0.0001
≦ z ≦ 0.05), and a lithium-containing composite oxide represented by x + y + z = 1] is used. As M of wherein said _{LiCo x M y Al z O 2} , Ti, is at least one selected Nb, and from Zr, non-aqueous electrolyte battery according to claim 1, wherein. 3. The method according to claim 2, wherein the electrolyte is a gel-like solid polymer.
The non-aqueous electrolyte battery according to claim 1. 4. An exterior body that is deformed by a slight increase in battery internal pressure is used as the exterior body.
Or the non-aqueous electrolyte battery according to 3. 5. The nonaqueous electrolyte battery according to claim 4, wherein an aluminum laminate exterior body is used as the exterior body deformed by a slight increase in battery internal pressure.