JPH10188980A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion battery with large battery capacity and energy density. SOLUTION: This battery has lithium occluded/released positive electrode active material and negative electrode active material 1 and lithium ion conducive nonaqueous electrolyte. The negative electrode active material in the charged condition contains lithium contained composite oxide Lix My Oz (where 0.1<=x/y<=8, 0.1<=z/y<=4, and M mainly contains at least one kind out of a typical group element IIIB or VB, Ge, Sn and Pb) and lithium compound Lis M't (where 0.01<=s/t<=8, and M' mainly contains at least one kind of a typical group element IIIB or VB, Ge, Sn and Pb).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art Conventionally, lithium, its alloys, and carbonaceous materials capable of inserting and releasing lithium have been used as negative electrode active materials for lithium secondary batteries.

However, when lithium or an alloy thereof is used as a negative electrode active material, lithium metal precipitates and grows in a resinous state during charge and discharge, and is liable to cause an internal short circuit. And so on. In addition, even in a carbonaceous material capable of inserting and releasing lithium, in addition to the precipitation of lithium metal in an overcharged state, the volume density is low due to the low density, and the capacity density per volume when a battery is formed cannot be improved. There was a problem.

For this reason, oxides or chalcogen compounds capable of occluding and releasing lithium have been studied as negative electrode active material materials. However, all transition metal oxides have a high operating potential and constitute a 3.6 V class battery. I couldn't.

As oxides having a low operating potential and a high capacity battery voltage and a high capacity, lithium-containing composite oxides mainly composed of silicon (JP-A-6-325765, JP-A-7-230800)
Publication), lithium-containing composite oxides mainly composed of group IVB and VB elements (JP-A-7-122274), III, IVB, V
A lithium-containing composite oxide mainly composed of a group B element (Japanese Patent Application Laid-Open No. 7-288123) is known.

[0006]

SUMMARY OF THE INVENTION A lithium-containing composite oxide mainly composed of silicon (JP-A-6-325765, JP-A-7-325765)
-230800) as a negative electrode active material cannot be extended to a high-capacity system containing no silicon due to the provision of silicon. Lithium-containing composite oxides mainly composed of IVB and VB group metalloid elements
In the prior art in which a negative electrode active material is used as a negative electrode active material, it is described that the constituent element is used in a range that does not alloy with lithium, and the increase in capacity is insufficient. II
Oxides and / or chalcogenides containing two or more elements selected from Group I, IVB and VB elements (JP-A-7-28812)
No. 3) as a negative electrode active material,
Although there is a description of adding a lithium alloy, it is described that these are not used as a battery reaction,
Since the electrode reaction of alloying is not used, the increase in capacity is insufficient.

An object of the present invention is to provide a lithium secondary battery having a large energy density per volume and weight.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-aqueous electrolyte secondary battery including a positive electrode active material for absorbing and releasing lithium, a negative electrode active material, and a lithium ion conductive non-aqueous electrolyte. Before or after the configuration, the charge termination potential of the negative electrode is set to L
By the i reference range of 0-0.5V, a negative electrode active material in charged state, the lithium-containing composite oxide Li _x M _y
O _z (However, 0.1 ≦ x / y ≦ 8, 1 ≦ z / y ≦ 4, M
Represents at least one of the group IIIB and VB typical elements, Ge, Sn and Pb) and the lithium compound Li
_s M ′ _t (where 0.01 ≦ s / t ≦ 8, M ′ is IIIB,
VB group typical element, at least one of Ge, Sn and Pb).

The positive electrode active material of the present invention preferably uses a lithium-containing transition metal composite oxide, particularly LiCo.
It is preferable to use O ₂ , LiNiO ₂ , and LiMn ₂ O ₄ . As the electrolyte solvent of the present invention, it is preferable to use a mixture of at least one of alkyl carbonate, a partially substituted alkyl carbonate, methyl propionate, ethyl propionate, and 1,2-dimethoxyethane. A mixed solvent of carbonate and dimethyl carbonate or a mixed solvent of ethylene carbonate and diethyl carbonate is preferred.

As the electrolyte supporting salt of the present invention, it is preferable to use a lithium compound having a lithium dissociation property and a halogen element, particularly LiPF ₆ .

Incidentally, a transition metal element can be added to the negative electrode active material of the present invention.

The discharge capacity can be increased by amorphizing the negative electrode active material or the negative electrode active material precursor of the present invention.

According to the non-aqueous electrolyte secondary battery of the present invention, the negative electrode can be used to a low potential at which lithium is alloyed, so that a large discharge capacity and a low operating potential can be obtained. Therefore, the capacity as a battery is large, and the operating voltage is also large. Thereby, the energy density of the battery is also improved.

Further, the lithium alloy electrochemically formed from the negative electrode of the present invention is fine, and it is possible to minimize the deterioration of cycle characteristics, which is a problem in a conventional electrode using a single lithium alloy as a negative electrode active material. it can.

Another problem is that the oxide negative electrode alone has a large retention during initial charging and discharging. In order to compensate for this, it is conceivable to mix lithium or a lithium alloy or the like in advance at the time of forming the electrode. However, it is difficult to design such that lithium or the lithium alloy does not exceed the retention amount of the oxide so as not to remain. Assuming that lithium or a lithium alloy is interposed, it is possible to interpose lithium or a lithium alloy in excess of the oxide retention amount, which facilitates design.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail.

(Synthesis Example 1) The following samples were prepared for evaluation of battery characteristics.

1) Tin oxide SnO ₂ , lead oxide PbO ₂ , germanium oxide GeO ₂ , indium oxide l ₂ O ₃ , bismuth oxide Bi ₂ O ₃ are mixed and mixed at a molar ratio of 9: 1, and the mixture is mixed in an argon atmosphere at 10K. / Min.
After being melted, it was cast on a copper rotating roll to prepare a quenched sample.

2) Tin oxide SnO, lead oxide PbO ₂ , germanium oxide GeO ₂ , indium oxide l ₂ O ₃ , bismuth oxide Bi ₂ O ₃ are mixed and mixed at a molar ratio of 9: 1, and the mixture is mixed in an argon atmosphere at 10 K / cm 2. After heating and melting at a temperature rising rate of min or more, the sample was cast on a copper rotating roll to prepare a quenched sample.

Further, commercially available tin oxides SnO ₂ and SnO were each evaluated alone.

After synthesizing the above sample, it was pulverized by a planetary ball mill, classified to 45 μm or less, and used for battery characteristics evaluation.

(Example 1) FIG. 1 is a sectional view of a cell for battery characteristic evaluation as a negative electrode material of the synthetic powder shown in Synthesis Example 1.

The negative electrode plate was subjected to the following procedure with a humidity of 3%.
It was produced in the following atmosphere.

The composition of the negative electrode mixture was 87: 8.7: 4.3 in terms of the weight ratio of the synthetic powder, the conductive material, and the binder. First, synthetic powder and conductive material graphite in a weight ratio are kneaded in a mortar, and then NM
A binder polyvinylidene fluoride diluted to 10 wt% with P was added and kneaded to obtain a mixture paste. The mixture paste was applied to electrolytic copper foil, and after pre-drying at 80 ° C. for 2 hours, 1.
After pressing with a load of 5 t ² / cm ² , it was dried at 120 ° C. for 2 hours.

The prepared negative electrode plate was arranged in a glove box with a lithium plate as a counter electrode and a reference electrode as shown in FIG. 1 and a polyethylene separator interposed therebetween to form a cell, and was housed in a sealed glass container. As the electrolytic solution, a mixture of ethylene carbonate and dimethyl carbonate in a ratio of 1: 2 to which 1 M / liter of LiPF ₆ was added as a supporting salt was used to impregnate the separator and the negative electrode active material.

The battery was subjected to a charge / discharge test at a current density of 40 mA per gram of the synthetic powder and in a potential range of ^{0 to} 1.5 V vs Li ⁺ / Li. Table 1 shows the results of the charge / discharge test. The discharge capacity is increased by utilizing the potential of the negative electrode in the range of 0-0.5 V vs Li ⁺ / Li.

[0027]

[Table 1]

[0028]

According to the non-aqueous electrolyte secondary battery of the present invention,
Since the negative electrode can be used up to a low potential at which lithium is alloyed, a large discharge capacity and a low operating potential can be obtained. Therefore, the capacity as a battery is large,
In addition, the operating voltage increases. Thereby, the energy density of the battery is also improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a battery characteristic evaluation cell as a negative electrode material of a synthetic powder shown in Synthesis Example 1.

[Explanation of symbols]

1: negative electrode active material, 2: negative electrode current collector, 3: lithium counter electrode,
4 ... lithium reference electrode, 5 ... separator, 6 ... SUS jig for cell fixing, 7 ... fixing bolt, 8 ... fixing nut.

Continued on the front page (72) Inventor Hideto Momomo 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Yoshi Komatsu 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 In Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Ren Muranaka 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture In Hitachi Research Laboratory, Hitachi, Ltd.

Claims (7)

[Claims] 1. A positive electrode active material for absorbing and releasing lithium,
And the anode active material, the non-aqueous electrolyte secondary battery comprising a lithium ion conductive non-aqueous electrolyte, the negative electrode active material in charged state, the lithium-containing composite oxide Li _x M _y O _z (where 0.1 ≦ x / y ≦ 8, 0.1 ≦ z / y ≦ 4, M is III
B, VB group typical element, at least one of Ge, Sn and Pb) and lithium compound Li
_s M ′ _t (where 0.01 ≦ s / t ≦ 8, M ′ is IIIB,
A non-aqueous electrolyte secondary battery comprising at least one of VB group typical elements, Ge, Sn and Pb). 2. A cell assembly before or after assembly, the precursor M _{y 'O z'} (except, 0.1 ≦ z '/ y' ≦ 8, M is III
B, VB group typical elements, Ge, Sn, Pb and at least one is mainly) lithium electrochemical or chemically reacting the with of Li, lithium-containing composite oxide was inserted lithium Li _x M _y O _z (However, 0.1 ≦ x / y
≦ 8,0.1 ≦ z / y ≦ 4 , M is IIIB, VB group typical elements, Ge, at least one of Sn and Pb is mainly) and lithium and M 'are alloyed Li _s M' _t ( 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein 0.01 ≦ s / t ≦ 8 and M ′ is mainly formed of at least one of IIIB and VB group typical elements, Ge, Sn and Pb. . 3. The charge end potential of the negative electrode is 0-
The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte secondary battery has a range of 0.5 V. 4. 4. The non-aqueous electrolyte secondary battery according to claim 1, wherein said positive electrode active material is a lithium-containing transition metal composite oxide. 5. The electrolyte solvent according to claim 1, wherein a mixture of at least one of alkyl carbonate, a partially substituted alkyl carbonate, methyl propionate, ethyl propionate, and 1,2-dimethoxyethane is used. 4. The non-aqueous electrolyte secondary battery according to 2 or 3. 6. The non-aqueous electrolyte secondary battery according to claim 1, wherein a lithium-dissociable halogen-containing lithium compound is used as a supporting electrolyte. 7. Computers and their connected peripherals, information and communication equipment, video and audio equipment, cooling and heating equipment, lighting equipment, other home appliances, watches, calculators, toys, tools, medical equipment,
Uninterruptible power supply, power storage system, automobile, other vehicles,
Claims 1, 2, 3, 4, 5 for use in satellites and submarines
Or the non-aqueous electrolyte secondary battery according to 6.