JPH01173575A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PURPOSE:To make it possible to acquire an excellent cycle characteristic by using an amorphous material, as a positive pole active material, which is obtained by melting a mixture of copper (II) oxide and vanadium (V) oxide or a mixture of them and a vitrification agent and cooling the mixture rapidly. CONSTITUTION:An amorphous material obtained by a melting mixture of copper (II) oxide and vanadium (V) oxide or of them and a vitrification agent, and cooling the mixture rapidly, is used as a positive pole 1 active material. In the cases of the two components consisting of copper (II) oxide and vanadium (V) oxide and three components consisting of copper (II) oxide, vanadium (V) oxide and the vitrification agent, the mole ratios are preferably CuO:V2O5=5:95 to 30:70 and CuO:V2O5:vitrification agent=5:90:5 to 30:55:15 respectively. Consequently, it is possible to acquire an excellent cycle characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-aqueous electrolyte secondary battery that has high energy density, long charging/discharging life, and excellent stability and reliability.

The days are getting longer. Many proposals have been made regarding high energy density batteries, and lithium batteries using lithium as a negative electrode active material and fluorinated graphite or manganese dioxide as a positive electrode active material are already on the market.

However, these batteries are primary batteries and have the disadvantage that they cannot be recharged.

For secondary batteries that use lithium as the negative electrode active material, titanium and molybdenum are used as the positive electrode active material.

Batteries using chalcogenides (sulfides, selenides, tellurides) of niobium, vanadium, and zirconium have been proposed, but few have been put into practical use because the battery characteristics and economic efficiency are not necessarily sufficient. recently,
Secondary batteries using molybdenum sulfide have been put into practical use, but they also have drawbacks such as low discharge potential and vulnerability to overcharging. Chromium oxide is a positive electrode active material with a high discharge potential.
Vanadium pentoxide and the like are known, but chromium oxide has poor charge-discharge cycle characteristics, vanadium pentoxide has low conductivity, and has not yet achieved sufficient cathode properties. It has also been proposed to use an amorphous material obtained by adding phosphorus pentoxide to vanadium pentoxide and rapidly cooling it after melting as a positive electrode active material (Solid 5t
ate Ionics 9 &10.649-654 (
1983)), when this is also used as a secondary battery, the capacity after the second cycle is low, and the charging and discharging characteristics cannot be said to be sufficient.

Therefore, it is desired to develop a secondary battery that has high energy density, long charging/discharging life, and excellent stability and reliability.

The present invention has been made in view of the above circumstances, and by using a positive electrode active material with a large capacity, it is possible to achieve high energy density by reducing the amount of conductivity imparting agent added, and also has a large charge/discharge capacity and a high potential. The purpose is to provide a non-aqueous electrolyte secondary battery with excellent cycle characteristics.

. In order to achieve the above object, the inventors of the present invention have made extensive studies and found that after melting a mixture containing copper oxide and vanadium pentoxide or a mixture in which a vitrifying agent is added thereto, the present inventors melt the mixture and then rapidly cool it. The amorphous material obtained by this process has good conductivity and high capacity, and when a non-aqueous electrolyte secondary battery is constructed using this amorphous material as a positive electrode active material, it is possible to achieve high energy density and They discovered that it was possible to obtain a non-aqueous electrolyte secondary battery with high potential and excellent cycle characteristics, and completed the present invention.

Therefore, the present invention uses an amorphous material obtained by melting a mixture containing copper oxide and vanadium pentoxide or a mixture containing a vitrifying agent and then rapidly cooling the mixture as a positive electrode active material. The present invention provides a non-aqueous electrolyte secondary battery with characteristics.

The present invention will be explained in more detail below.

As described above, the non-aqueous electrolyte secondary battery of the present invention uses, as a positive electrode active material, an amorphous material obtained by melting copper oxide, vanadium pentoxide, or a mixture containing these and a vitrifying agent, and then rapidly cooling the mixture. However, the vitrifying agent here may be any compound that promotes vitrification when a mixture of copper oxide and vanadium pentoxide is made amorphous, such as P2O5t Tea, Gem2. B20. ,
Sb, 03°Bi2O3, 5in2. Sea,,As
, 03, etc.

Further, the mixing ratio of these is not particularly limited, but in the case of two components of copper oxide and vanadium pentoxide, the molar ratio is CuO: V, O, = 5: 95 to 30 near 0. In the case of three components of copper oxide, vanadium pentoxide and vitrifying agent, it is preferable that CuO:V2O5 vitrifying agent=5:90:5 to 30:55:15.

Note that the method of making the mixture amorphous is to rapidly cool it in a melter, but specifically, using a twin roll quenching device, copper oxide and vanadium pentoxide or these and a vitrifying agent are thoroughly mixed, Preferably, the mixture is placed in a quartz nozzle, completely melted, and then jetted between twin rollers rotating at 2,000 to 4,000 rpm in a twin-roll quenching device to ultra-rapidly solidify the mixture.

Furthermore, when melting the mixture, 1 lithium oxide
By adding 0 to 30 mol%, the cycle characteristics of a battery can be further improved.

When creating a positive electrode using this positive electrode material, the particle size of the positive electrode material is not necessarily limited, but if one with an average particle size of 3 μm or less is used, a positive electrode with higher performance can be produced. In this case, the positive electrode is prepared by adding and mixing a conductive agent such as acetylene black or a binder such as fluororesin powder to these powders, kneading with an organic solvent, rolling with a roll, and drying. can be created. The amount of the conductive agent mixed is preferably 3 to 25 parts by weight, particularly 5 to 15 parts by weight, based on 100 parts by weight of the positive electrode material. The amount of the binder added is 2 to 2 parts by weight per 100 parts by weight of the above positive electrode material.
The amount is preferably 5 parts by weight.

As the negative electrode active material of the secondary battery of the present invention, lithium, a lithium alloy capable of inserting and releasing lithium, carbon or graphite containing lithium, etc. are preferably used.

In this case, the lithium alloy is II containing lithium.
Metals of groups a, IIb, Ha, IVa, Va or alloys of two or more thereof can be used, especially AQ, In, Sn, Pb, Bi containing lithium.

Cd, Zn, Sb, or an alloy of two or more of these is preferred.

Note that lithium and the metal to be alloyed can be alloyed with lithium by an electrochemical method in the battery container after the battery is constructed.

Furthermore, as the electrolyte used in the secondary battery of the present invention, an electrolyte that is chemically stable with respect to the positive electrode active material and the negative electrode active material, and that undergoes an electrochemical reaction with the positive electrode active material or the negative electrode active material. Any non-aqueous substance can be used as long as it has a negative ion capable of transferring, particularly Li+ as a cation and P Fa- as an anion.

Va such as AsFG-, 5bFG-, 5b (J2G'-)
Halide anion of group element, B F4-, AQC
■ Halide anions of group a elements such as Q4-, I'
”(I3-).

Halogen anions such as Br-, CQ-, CQO4'''
Perchlorate anions such as HFz'', CFa SO
Examples include compounds having anions such as 3-8CN-, but are not necessarily limited to these anions. A specific example of an electrolyte having such anions and cations is LiPF.

LiAsF, , Li5bF, , LiBF4. LiCQo
,.

LiI, LiBr, LiC<4. LiAflCQ,,L
Examples include iHF2°Li5CN, Li5O, CF3, and the like. Among these, especially LiPF, , LiAsF,
, LiBF4°LiCΩ04. LiSbF6. LiS○
, CF are preferred.

Note that the electrolyte is usually used in a state dissolved in a solvent, and in this case, the solvent is not particularly limited, but a relatively highly polar solvent is preferably used. Specifically, glymes such as propylene carbonate, ethylene carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, dioxane, dimethoxyethane, diethylene glycol dimethyl ether, lactones such as γ-butyrolactone, phosphoric acid esters such as triethyl phosphate, One or two types of boric acid esters such as triethyl borate, sulfur compounds such as sulfolane and dimethyl sulfoxide, nitriles such as acetonitrile, amides such as dimethylformamide and dimethylacetamide, dimethyl sulfate, nitromethane, nitrobenzene, and dichloroethane. Mixtures of the above may be mentioned.

Among these, especially ethylene carbonate, propylene carbonate, butylene carbonate.

Tetrahydrofuran, 2-methyltetrahydrofuran,
One or more mixed solvents selected from dimethoxyethane, dioxolane, and γ-butyrolactone are suitable.

Furthermore, as the electrolyte constituting the secondary battery of the present invention, the above electrolyte is impregnated with a polymer such as polyethylene oxide, polypropylene oxide, incyanate crosslinked product of polyethylene oxide, or a phosphazene polymer having an ethylene oxide oligomer in the side chain. Organic solid electrolyte, Li3N.

Inorganic ionic conductors such as LiCΩ4, Li2SiO3゜L
An inorganic solid electrolyte such as lithium glass such as i, BO, etc. can also be used.

The secondary battery of the present invention is usually constructed by interposing an electrolyte between the positive and negative electrodes, but in this case, a separator may be interposed between the positive and negative electrodes to prevent short-circuiting of current due to contact between the two electrodes. As the separator, it is possible to use porous materials that allow the electrolyte to pass through or be contained therein, such as nonwoven fabrics, woven fabrics, and nets made of synthetic resins such as polytetrafluoroethylene, polypropylene, and polyethylene.

1 Bad Jυ Results The nonaqueous electrolyte secondary battery of the present invention uses a high-capacity amorphous material as a positive electrode active material, so it has high energy density, excellent cycle characteristics at high potential, and stability. , and has excellent reliability.

EXAMPLES Hereinafter, the present invention will be specifically explained by showing examples and comparative examples of the present invention, but the present invention is not limited to the following examples.

[Examples 1 to 4] CuO, V2O5 and TaO2 were mixed at each mixing ratio shown in Table 1 below, the mixture was put into a quartz nozzle, and
After complete melting at 00℃, 2000℃ in a twin-roll quenching device
It was ejected between twin rollers rotating at ~4000 rpm and solidified by ultra-rapid cooling to obtain four types of thin scale-like amorphous materials. After thoroughly pulverizing these samples, 15 parts by weight of acetylene black as a conductive agent and 15 parts by weight of fluororesin powder as a binder were added to 100 parts by weight of the powder, and after thorough mixing, organic The mixture was kneaded with a solvent, rolled to about 450 pm with rolls, vacuum dried at 150° C., and punched out to a predetermined diameter, which was used as a positive electrode.

The negative electrode is made by pressing lithium onto an aluminum plate punched to a predetermined size, and then forming aluminum-lithium (AQ-L) in an electrolyte.
i) Using an alloyed product, lithium perchlorate (LiCRO4) was added in a mixed solvent of propylene carbonate and dimethoxyethane (volume ratio 1:1) at a rate of 1 mol/1.
Using the solution dissolved in Ω as an electrolyte, four types of batteries as shown in the drawings were assembled.

Here, in the drawing, 1 is a positive electrode, 2 is a positive electrode current collector made of stainless steel, and the positive electrode 1 and current collector 2 are integrated, and the current collector 2 is spotted on the inner bottom surface of the positive electrode can 3. Welded. Further, 4 is a negative electrode, 5 is a negative electrode current collector, and the negative electrode 4 is spot-welded to the current collector fixed to the inner bottom surface of the negative electrode can 6.

Furthermore, 7 is a separator made of polypropylene nonwoven fabric, which is impregnated with the electrolytic solution. In addition, 8
is an insulating backing. Also, the battery dimensions are 20mm in diameter.
The thickness is 0 mm and the thickness is 1.6 nm.

Next, the discharge voltage of each of these four types of batteries was 1.5.
Charging and discharging were repeated by discharging until the voltage reached V and then charging until the charging voltage reached 3.3 V, and the discharge capacity at the fifth cycle of each was measured. Table 1 shows the specific capacity per active material.

[Example 5] The composition of the positive electrode active material was CuO and v20. Batteries were prepared in the same manner as in Examples 1 to 4, except that the ratio was 25:75, and the same charge and discharge repeated tests as in Examples 1 to 4 were conducted, and the discharge capacity at the 5th cycle was determined. It was measured. Table 1 shows the specific capacity per active material.

[Comparative Examples 1 and 2] The composition of the positive electrode active material was v20. and Tea, the ratio of which is 95:5 (Comparative Example 1), and P2O5 and P2O
Two types of batteries were prepared in the same manner as in Examples 1 to 4 except that the ratio was 95=5.
A repeated charge/discharge test similar to 4 was conducted, and the discharge capacity at the 5th cycle was measured.

Table 1 shows the specific capacity per active material.

Table 1 From the results shown in Table 1, it was confirmed that the battery of the present invention had a large capacity and a long cycle life. Therefore,
According to the present invention, it is possible to obtain an excellent non-aqueous electrolyte secondary battery having a high discharge capacity, and its industrial value is extremely large.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of the battery used in the repeated charge/discharge test. DESCRIPTION OF SYMBOLS 1... Positive electrode, 2... Positive electrode current collector, -3... Positive electrode can, 4... Negative electrode, 5... Negative electrode current collector, 6... Negative electrode can, 7... Separator , 8... Insulating backing. Izukendai Brideston Co., Ltd. Agent Patent Attorney Takashi Kojima

Claims (1)

[Claims] 1. A non-crystalline material characterized in that the cathode active material is an amorphous material obtained by melting a mixture containing copper oxide and vanadium pentoxide or a mixture to which a vitrifying agent is added and then rapidly cooling the mixture. Water electrolyte secondary battery.