JPH0763010B2 - Organic electrolyte battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic electrolyte battery (so-called lithium battery) using lithium or a lithium alloy as a cathode and an organic electrolyte as an electrolyte, and particularly Li The present invention relates to an improvement in an organic electrolyte battery using a composite oxide of a metal and a transition metal as an anode active material.

[Outline of Invention]

The present invention provides LiNi _x Co _(1-x) as an anode material for an organic electrolyte battery.
By using the composite metal oxide represented by O ₂ (where 0 <x ≦ 0.27), it is completely compatible with the mercury battery in terms of operating voltage, has a large battery capacity, and is non-polluting. It aims to provide an entirely new battery system.

[Conventional technology]

In recent years, various electronic devices such as watches, cameras, and calculators have been miniaturized, and silver oxide batteries and mercury batteries, which are small and thin and have high energy density among aqueous batteries, are used for these devices. There is.

However, as interest in environmental pollution increases,
Since not only mercury batteries but also silver oxide batteries use zinc amalgam as the cathode, the relation to the pollution associated with the disposal of these mercury batteries and silver oxide batteries has been proposed.

Under such circumstances, the advent of pollution-free batteries compatible with mercury batteries and silver oxide batteries is strongly desired.

On the other hand, a lithium battery that uses lithium or a lithium alloy for the cathode and an organic electrolyte for the electrolyte has excellent storage stability and has a large energy density, so it can be made small and thin, and it also uses mercury. Since it is non-polluting because it is not present, it is beginning to be used in various electronic devices.
For example, a material using MnO ₂ , CF _x , AgCrO ₄ or the like as an anode active material has been put into practical use.

However, since these lithium batteries have a high battery voltage of 3 V, they have a difficulty in compatibility with conventional silver batteries and mercury batteries. Therefore, development of lithium batteries compatible with these silver oxide batteries and mercury batteries has been promoted, and Fe as an anode active material has been developed.
Lithium batteries and the like have been proposed in which S, FeS ₂ , CuO and the like are used and are combined with a lithium cathode. Such a lithium battery has a battery voltage of 1.5 to 1.6 V, which is almost the same as a silver oxide battery, and compatibility with the silver oxide battery is secured. However, since the battery voltage of the mercury battery is as low as 1.3 V, a lithium battery that is completely compatible with this mercury battery is not known.

Therefore, the applicant of the present application previously proposed an organic electrolyte battery that uses a composite oxide of Li and a transition metal as an anode material and exhibits a battery voltage almost equal to that of a mercury battery.

[Problems to be solved by the invention]

The present invention is intended to further improve an organic electrolyte battery using such a composite oxide as an anode material.

That is, the present invention aims to increase the battery capacity of an organic electrolyte battery using a composite oxide of Li and a transition metal as an anode material.

[Means for solving problems]

As a result of various studies using LiCoO ₂ as a basic active material, the present inventors have found that replacing a part of cobalt atoms with nickel atoms results in very good characteristics as an active material. The organic electrolyte battery of the present invention has been completed on the basis of such findings, and includes a cathode made of lithium or a lithium alloy and LiNi _x Co _(1-x) O ₂ (where 0 <x ≦
It is 0.27. ) Is composed of an anode made of a composite metal oxide and an organic electrolyte.

In the present invention, a composite oxide of Li, Co and Ni is used as the anode material, but this composite oxide is easily mixed by mixing Li carbonate, Co carbonate and Ni carbonate and heat-treating. Can be synthesized.

In addition, in the organic electrolyte battery using LiNi _x Co _(1-x) O ₂ as the anode material, the capacity increases as the value of x increases.
That is, if 0 <x, an effect can be expected in that the discharge capacity increases. However, if the value of x becomes too large, in other words, if the content of nickel becomes too large, the battery voltage will decrease. Therefore, when considering the use as a substitute for the mercury battery, the value of x is 0 <x ≦
The range is preferably 0.27, and more preferably 0.07 ≦ x ≦ 0.22. When the value of x exceeds 0.27, the apparent discharge capacity until the battery voltage reaches 1.2V sharply decreases. However, when the battery voltage may be low to some extent, the value of x may exceed the above range in terms of battery life.

On the other hand, as the cathode active material, other than lithium, LiAl alloy,
An alloy of Li and one or more of Al, Pb, Sn, Bi, Cd, etc. can be used.

A non-aqueous organic electrolyte prepared by dissolving a lithium salt in an electrolyte and dissolving it in an organic solvent is used as the electrolytic solution.

Here, as the organic solvent, esters, ethers, 3
Substituted-2-oxazolidinones and mixed solvents of two or more of these may be mentioned.

Examples of the esters include alkylene carbonate (ethylene carbonate, propylene carbonate, γ-butyrolactone, etc.) and the like.

The ethers include cyclic ethers, for example, ethers having a 5-membered ring [tetrahydrofuran; substituted (alkyl,
Alkoxy) tetrahydrofuran, for example 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2-
Ethyltetrahydrofuran, 2,2'-dimethyltetrahydrofuran, 2-methoxytetrahydrofuran, 2,5-dimethoxytetrahydrofuran, etc .; dioxolane, etc.], ether having a 6-membered ring [1.4-dioxane, pyran, dihydropyran, tetrahydropyran], dimethoxyethane Etc.

The 3-substituted-2-oxazolidinones include 3-alkyl-2-oxazolidinone (3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, etc.), 3-
Cycloalkyl-2-oxazolidinone (3-cyclohexyl-2-oxazolidinone, etc.), 3-aralkyl-2
-Oxazazolidinone (3-benzyl-2-oxazolidinone, etc.), 3-aryl-2-oxazolidinone (3-
Phenyl-2-oxazolidinone and the like).

Among them, propylene carbonate, ether having a 5-membered ring (particularly tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2-methoxytetrahydrofuran), and 3-methyl-2-oxazolidinone are preferable.

As the electrolyte, lithium perchlorate, lithium borofluoride, lithium phosphofluoride, lithium chloroaluminate, lithium halide, lithium trifluoromethanesulfonate and the like can be used, and lithium perchlorate and lithium borofluoride are preferable.

[Action]

By using LiCoO ₂ which is a composite oxide of Li and Co as a basic active material and replacing some of the cobalt atoms with nickel atoms, the discharge capacity of the organic electrolyte battery using this as an anode material increases.

In particular, the value of x of LiNi _x Co _(1-x) O ₂ which is the anode material is 0 <x ≦
By setting it to 0.27, an organic electrolyte battery having a larger capacity than a battery using LiCoO ₂ as an anode material can be obtained, and a sufficient battery voltage can be secured to substitute for a mercury battery.

〔Example〕

 Hereinafter, the present invention will be described based on specific experimental results.

Example of composite oxide synthesis Commercially available lithium carbonate powder and cobalt carbonate powder were mixed so that the ratio of lithium atoms and cobalt atoms was 1: 1 and the mixture was fired in air at 900 ° C for 5 hours to obtain a lithium cobalt composite oxide (LiCoO). ₂ ) got The X-ray diffraction pattern of the obtained lithium cobalt composite oxide is shown in FIG. 1A.

Next, in order to replace the cobalt atom of the lithium-cobalt composite oxide with the nickel atom, lithium carbonate (Li
CO ₃ ), cobalt carbonate (CoCO ₃ ), nickel carbonate (NiC
O ₃ ) is mixed to match the composition of LiNi _x Co _(1-x) O ₂ ,
Baked. That is, depending on the value of each x, mixed firing was performed so that the lithium atom, the nickel atom, and the cobalt atom became 1: x: 1-x. The firing conditions were 900 ° C. in air for 5 hours, similar to the lithium cobalt composite oxide.

1B to 1G show X-ray diffraction patterns of these composite oxides, and FIG. 1B shows LiNi _0.1 Co _0.9 O ₂ ,
Figure 1C shows LiNi _0.2 Co _0.8 O ₂ and Figure 1D shows LiNi _0.4 Co.
_0.6 O ₂ , FIG. 1E shows LiNi _0.6 Co _0.4 O ₂ , and FIG. 1F shows LiNi _0.8.
Co _0.2 O ₂ and FIG. 1G show LiNiO ₂ , respectively.

As is clear from the X-ray diffraction patterns shown in FIGS. 1A to 1G, it is found that in LiNi _x Co _(1-x) O ₂ , cobalt and nickel are replaced at a free ratio.
The reason is that the basic pattern of LiCoO _{2 with} x = 0 (FIG. 1A) does not change, the X-ray diffraction pattern gradually changes according to the value of x, and finally LiNiO _{2 with} x = 1. This is because the pattern (Fig. 1G) changes.

Example The composite oxide prepared in the previous composite oxide synthesis example [LiNi _x C
o _(1-x) O ₂ (x = 0 to 1)] 70 parts by weight of graphite
27 parts by weight and 3 parts by weight of polytetrafluoroethylene powder serving as a binder were mixed and compacted to prepare an anode pellet having a diameter of 10.3 mm and a thickness of 0.5 mm.

Next, as shown in FIG. 2, a lithium foil (2) having a diameter of 12.3 mm and a thickness of 1.6 mm is punched out and press-bonded to the anode cup (1), and a separator (3) containing an electrolyte solution is further formed thereon. , Put the plastic gasket (4) on it, put the prepared anode pellet (5) on the separator (3), cover the cathode can (6), and crimp the end to seal the organic electrolyte battery. Assembled. The electrolyte used was propylene carbonate in which lithium perchlorate was dissolved at a rate of 1 mol / mol.

These batteries are discharged through a 6.5 kΩ resistor,
Discharge time up to 1.2V was measured and the anode material LiNi _x Co
The discharge time per unit weight (1 mg) of _(1-x) O ₂ was determined.
Results are shown in FIG.

As shown in Fig. 3, in the battery using LiNi _x Co _(1-x) O ₂ as the anode material, its discharge capacity changes depending on the value of x, and when a part of cobalt is replaced by nickel, it is compared to LiCoO ₂ . It was found that the discharge capacity increased. However, this replacement is also x ≧
It was also found that at 0.27 the capacity decreased with increasing nickel.

Therefore, according to the present embodiment, the composite oxide LiNi _x Co _(1-x) O ₂ consisting of three elements of lithium, cobalt and nickel is excellent as a battery active material, and particularly, the value of x is 0 <x.
≤0.27 selected with some cobalt atoms replaced with nickel atoms is based on the reaction shown by the following formula: LiMO ₂ + 3Li → 2Li ₂ O + M (1) (where M is a transition metal). It has been proved that it is an excellent battery active material in an organic electrolyte battery which is a battery reaction.

Figure 4 shows the maximum discharge capacity of Li / LiNi _0.1 Co _0.9 O ₂
FIG. 3 is a characteristic diagram showing discharge curves of a battery in comparison with those of a Li / LiCoO ₂ battery and a Li / LiNiO ₂ battery. Also from this FIG.
The superiority of using LiNi _x Co _(1-x) O ₂ as the anode material was confirmed. That is, in the battery using LiCoO ₂ as an anode material, there is no problem in terms of discharge voltage, but discharge capacity remains unsatisfactory. On the other hand, in the battery using LiNiO ₂ as the anode material, the discharge curve is flat and shows good characteristics for battery life.
The discharge voltage is a little low, and when the final voltage is 1.2V, the battery capacity is almost out of reach.

On the other hand, the battery using LiNi _0.1 Co _0.9 O ₂ as the anode material,
Both discharge voltage and discharge capacity showed good characteristics.

〔The invention's effect〕

As is clear from the above description, in the present invention,
Since LiCoO ₂ is used as the basic active material and some of the cobalt atoms thereof are replaced with nickel atoms as the anode active material, the discharge capacity of the battery is significantly improved.

In addition, the organic electrolyte battery using the composite oxide of Li and transition metal as the anode material has few problems from the viewpoint of pollution, etc., and has an operating voltage of 1.2 to 1.3 V, which is compatible with mercury batteries, and is a completely new battery system. Is.

[Brief description of drawings]

1A to 1G are spectrum diagrams showing X-ray diffraction patterns when the value of x is changed stepwise from 0 to 1 in LiNi _x Co _(1-x) O ₂ . Figure A shows LiCoO ₂ (X
= 0), Fig. 1B shows LiNi _0.1 Co _0.9 O ₂ , and Fig. 1C shows LiNi _0.2.
Co _0.8 O ₂ , Figure 1D shows LiNi _0.4 Co _0.6 O ₂ , Figure 1E shows LiNi
_0.6 Co _0.4 O ₂ , Fig. 1F shows LiNi _0.8 Co _0.2 O ₂ , Fig. 1G shows Li
The X-ray diffraction patterns of NiO ₂ (X = 1) are shown respectively. FIG. 2 is an enlarged cross-sectional view showing an example of the structure of the organic electrolyte battery. Figure 3 shows _{x in} a battery with LiNi _x Co _(1-x) O ₂ as the anode material.
It is a characteristic view showing the relationship between the value of and the discharge time per unit weight. FIG. 4 is a characteristic diagram showing discharge curves of a battery using LiNi _0.1 Co _0.9 O ₂ as an anode material in comparison with those of a battery using LiCoO ₂ as an anode material and a battery using LiNiO ₂ as an anode material. 2 ... Lithium foil (cathode) 3 ... Separator 5 ... Anode pellet

Claims (1)

[Claims] 1. A cathode made of lithium or a lithium alloy, an anode made of a composite metal oxide represented by LiNi _x Co _(1-x) O ₂ (where 0 <x ≦ 0.27), and an organic electrolyte. An organic electrolyte battery composed of