JPH03228826A - Production of lithium-containing vanadium oxide - Google Patents

Abstract

PURPOSE:To obtain the powdery lithium-contg. vanadium oxide appropriate as the positive electrode active material for a galvanic cell and which need not be crushed by mixing vanadium pentoxide and a specified lithium compd. and subjecting the mixture to a solid-phase reaction at a specified calcination temp. CONSTITUTION:(A) Vanadium pentoxide and (B) a lithium compd. selected from Li2O, Li2O2, LiOH, LiNO3, LiI, LiCH3CO2 and Li2C2O4 or their hydrated compds. are mixed. The mixture is then calcined at <500 deg.C to allow the A component to react with the B component in a solid phase, and the lithium- contg. vanadium oxide expressed by the formula (0<=x<=0.6 and -0.5<=y<=0.3) is obtained in the form of powder. Consequently, when the product is applied to the positive electrode active material for a galvanic cell, crushing and classification can be omitted, the production process is simplified, and the positive electrode is efficiently produced.

Description

[Detailed description of the invention] The present invention is based on L 11+xVa Os+y (0≦x≦0
．． Regarding the method for producing a lithium-containing vanadium oxide represented by 6°-0.5≦y≦0.3, in more detail,
The present invention relates to a method for producing a lithium-containing vanadium oxide that has a high potential and a high energy density and is suitably used as a positive electrode active material for non-aqueous electrolyte secondary batteries.

V2 has been used as a positive electrode active material for non-aqueous electrolyte secondary batteries since it is expected to expand in the future.
O,, v, o□,, v, o,, amorphous V 20 s
' P 20 s -L I 0.3 V20s r
Vanadium oxides such as L i V3011 have been proposed. Among them, it has been reported that a lithium-2-lamum-containing vanadium oxide represented by Li1+xv308 (x=0.05 or x=0.2) can be used as a positive electrode active material with high energy density (G).

Pistoia et al., J., Electr.
ochem, Soc, Vol.

133, Nα12. P2454-2458.1986)
.

However, the synthesis method of lithium-containing vanadium oxide shown here uses Li2Co and V2O5 at 650~
This is a melt synthesis method in which the material is synthesized by melting it at 680° C., but the material obtained by this method becomes lumpy when cooled. For this reason, when used as a cathode active material for a battery, a pulverization process and a classification process are required, making the manufacturing process complicated. Also, 500-560℃
A method of synthesis at a temperature of (D, GW) has also been proposed.
iehhamtJ, Inorg, Nuch,
Chew, Vol, 27, 1939-1946, 1
965), when the reaction is completed in this temperature range, the product becomes a lava-like mass of fused powder, which also requires pulverization and classification steps.

For this reason, when synthesizing a lithium-containing vanadium oxide as a positive electrode active material for a non-aqueous electrolyte secondary battery, it is preferable to obtain the oxide in powder form for the electrode manufacturing process, and such a synthesis method Development is desired.

The present invention was made in view of the above circumstances, and L i i
+xVa Oa+y (0≦x≦0.6.-0.5≦y
An object of the present invention is to provide a method for producing a lithium-containing vanadium oxide, which is capable of synthesizing the lithium-containing vanadium oxide represented by ≦0.3) in a powder state.

In order to achieve the above-mentioned object, the present invention mixes vanadium pentoxide and a lithium compound and burns them to form L l 1+xV.
20a+y (0≦x≦0.6.-0.5≦y≦0.3
), in which the lithium compound is Li2O, L
i, 02. LiOH, LiNo.

Using a lithium compound selected from LiI, LiCH, Co□, Li2C2O4 or a water-containing compound thereof, 5
4- A method for producing a lithium-containing vanadium oxide, characterized in that the vanadium pentoxide and the lithium compound are subjected to a solid phase reaction at a firing temperature of less than 00°C;
Then, vanadium pentoxide and a lithium compound are mixed and fired to obtain L 1 x+xVa Os+y (0≦x≦0.6
゜-〇, 5≦y≦0.3) In the method for producing a lithium-containing vanadium oxide, Li2Co3 is used as the lithium compound, pre-calcined at a temperature of 500 to 600°C, and then remixed. Provided is a method for producing a lithium-containing vanadium oxide, characterized in that the above-mentioned vanadium pentoxide and Li2Co3 are subjected to a solid phase reaction by main firing at a temperature of less than 500°C.

That is, the present inventor has determined that L i , , V2O−+y (0≦
x≦0.6. -0.5≦y≦0.3) by mixing and firing vanadium pentoxide (V 20 S ) and a lithium compound, and various studies were conducted on methods to obtain the reaction product in powder form. As a result, lithium compounds such as lithium oxide (Li20 or Li2O□), lithium hydroxide (LiOH), and lithium nitrate (LiN
O3)-lithium iodide (LiI), lithium acetate (L
500
The solid phase reaction can be carried out well at a temperature below ℃, preferably 200 to 500℃, and L l 1+XV30e+y
It has been found that a product having the formula (0≦x≦0.6.-0.5≦y≦0.3) can be obtained in powder form. Also, as a lithium compound, lithium carbonate (Li2GO
3) can also be used, in this case 500 to 6
They found that it is possible to obtain a product in powder form by pre-calcining at a temperature of 00°C, remixing this, and then main-calcining at a temperature of less than 500°C, and completed the present invention. This is what I did.

The present invention will be explained in more detail below.

The method for producing lithium-containing vanadium oxide of the present invention includes:
As mentioned above, V, O, and Li2O, Li2O2゜L
iOH, LiNO3, Li I, LiCH, CO2゜L
A lithium compound selected from i2C2O4 or a hydrous compound thereof or Li2CO3 is mixed and heated at 500°C.
When Li2Co3 is used, it is pre-fired at a temperature of 500 to 600°C and remixed before firing at a temperature of less than 500°C.

Here, the mixing ratio of the above ■20s and the lithium compound is:
Although not particularly limited, the V:Li ratio is 3:0.8 to 3:1
．． 4, particularly preferably 3:0.9 to 3:1.2.

Further, the firing temperature (reaction temperature) is less than 500°C,
Preferably it is 200-500°C. The lower limit temperature for calcination is not particularly limited, but is usually higher than the melting point or decomposition temperature of the lithium compound used. The treatment time (reaction time) is also not limited, but X-ray diffraction of the product (Cu
The peak intensity near 2θ=20.4° due to Ka line) is 2
It is preferable to repeat the mixing and firing until the peak intensity is less than twice the peak intensity around 0=23.4°, thereby making it possible to obtain a positive electrode active material for batteries with even higher performance.

Note that when Li2Co3 is used as the lithium compound, the pre-calcination temperature is 500 to 600°C as described above.
However, this preliminary firing produces V2O.

7- The temperature and treatment time are set to such an extent that partial reaction between Li2Co and Li2CO3 occurs, but fusion between powder particles does not occur. Specifically 450-50
Preferably, the treatment is carried out at 0°C for 6 to 48 hours. Other firing conditions can be set to normal conditions for both preliminary firing and main firing, but the atmosphere during firing is usually air or oxygen atmosphere.

Note that the lithium-containing vanadium oxide obtained by the production method of the present invention is as described above.

It is expressed as L l l + XV30s + y, and the value of The value of this X changes from 0 to about 5 during charging and discharging. Moreover, the value of y changes in the range of -0.5 to 0.3 depending on the oxidation state of vanadium (V). In addition, the more preferable range of this Xe'j is that X is O-0.1°y is -0.3 to 0.

The lithium-containing vanadium oxide produced by the production method of the present invention is suitably used as a positive electrode active material for non-aqueous electrolyte secondary batteries. When creating a battery positive electrode as an active material, these powders are mixed with a conductive agent such as acetylene black, a binder such as fluororesin powder, etc., kneaded with an organic solvent, rolled with a roll, A positive electrode can be created by a method such as drying. In this case, the particle size of the positive electrode material is not necessarily limited, but a positive electrode with higher performance can be produced by using one with an average particle size of 3μ or less, and the amount of the conductive agent mixed is 100 parts by weight of the active material. On the other hand, it can be set at 3 to 25 parts by weight, especially 5 to 15 parts by weight, and in the present invention, since the conductivity of the active material is good, the amount of the conductive agent used can be reduced. In addition, the amount of the binder is 10% of the above positive electrode material.
The amount is preferably 2 to 25 parts by weight relative to 0 parts by weight.

As the negative electrode active material to be combined with the positive electrode, lithium metal or a lithium alloy capable of intercalating and deintercalating lithium is used. In this case, the lithium alloys include Ila, IIb, l1la, and IVa containing lithium.

9- Va group metals or alloys of two or more thereof can be used, especially AQ, In, Sn containing lithium.

Pb, Bi, Cd, Zn, or an alloy of two or more of these is suitable.

In addition, as an electrolyte, it is chemically stable with respect to the positive electrode active material and the negative electrode active material, and allows lithium ions to move for an electrochemical reaction with the positive electrode active material or the negative electrode active material. Any non-aqueous substance that can be obtained can be used, specifically LiP Fr,
, LiA s F,.

LiS b F,, LiB F4. LiCQO,,
LiI, LiBr.

LiCJ, LiA12CQ4. LiHF2. Li5CN
.

Li503CF, etc. are mentioned. Among these, especially LiPF6. LiAsF, LiCQO4 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, cyclic 10-carbonates such as propylene carbonate, ethylene carbonate, and butylene carbonate, acyclic carbonates such as diethyl carbonate and dibutyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, dioxane, dimethoxyethane, and diethylene glycol dimethyl ether. lactones such as γ-butyrolactone, phosphoric acid esters such as triethyl phosphate, boric acid esters such as triethyl borate, sulfolane, sulfur compounds such as dimethyl sulfoxide,
Nitriles such as acetonitrile, amides such as dimethylformamide and dimethylacetamide, dimethyl sulfate,
Examples include one or a mixture of two or more of nitromethane, nitrobenzene, dichloroethane, and the like. Among these, particularly preferred are one or more mixed solvents selected from cyclic carbonates such as ethylene carbonate and propylene carbonate, and acyclic carbonates such as diethyl carbonate. Moreover, 3 to 10% by weight of aromatic hydrocarbons (benzene, toluene, etc.) can be added to these solvents.

According to the production method of the present invention, Li1+xV3O8+7(
0≦x≦0.6. -0.5≦y≦0.3) can be synthesized in powder form, and therefore, when the product is applied to a positive electrode active material for batteries, a pulverization process and a classification process are required. This can be omitted, simplifying the manufacturing process, and making it possible to efficiently manufacture the positive electrode with less loss. Furthermore, by using the lithium-containing vanadium oxide as a positive electrode active material, a high-performance non-aqueous electrolyte battery with a high average potential and little capacity loss during high-rate discharge can be obtained.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples below.

[Example 1] 3 moles of V2O, and 2 moles/Lz(7)LiOH-I20
After mixing thoroughly, heat at 450℃ in air for 6 hours,
After further mixing well, the mixture was heated again at 450° C. for 12 hours to complete the reaction, and a powdered Li-V oxide was obtained. The X-ray diffraction (CuKα) pattern of this powder is that of Li V30a (or r, i V3 o) melt-synthesized at 750°C.
7. s). Also, the ratio of the peak intensity at 20.4° to the peak intensity at 23.4° for this powder is (I2
゜,,h/I 2. ,,) was 1.2.

[Example 2] 3 moles of V2O5 and 2.1 moles of LiN0. After mixing thoroughly, the process of heating at 400℃ x 6 hours in air and remixing was repeated three times to complete the reaction, and powdered L
An i-V oxide was obtained. X-ray diffraction of this powder (CuKα)
The pattern was the same as in Example 1. Also, this powder I
The value of 2°, 4/I23.4 was 0.8.

[Example 3] After thoroughly mixing 3 moles of V2O5 and 1 mole of Li2CO3, they were preheated in air at 550°C for 6 hours. The material obtained here was still in powder form.

This was thoroughly remixed and reheated at 490°C for 12 hours to complete the reaction, yielding a powdered Li-V acid 3-oxide. The X-ray diffraction pattern of the obtained powder (Cu
Kα) was the same as in Example 1. Also, I2 of this powder
°, the value of 4/I23.4 was 1.9 (see drawing)
.

[Comparative Example 1] 3 moles (7) V2O and 1 mole of Li2CO3 were thoroughly mixed and reacted by heating at 750° C. for 6 hours in air.

The melt was poured into a copper block and cooled to obtain a lump. After crushing this in a crusher for 3 hours, it was passed through a 200-mesh sieve, and the resulting powder was 70% of the original lumps.
It was about 0% by weight. Furthermore, those that did not pass through the 200-mesh sieve were re-pulverized for 2 hours and passed through the 200-mesh sieve again, resulting in a recovery rate of about 90% by weight, including the previous one. The X-ray diffraction pattern of this powder was the same as in Example 1. Also I20.4/I2
The value of 3.4 was 0.4.

[Comparative Example 2] 3 moles of V2O5 and 1 mole of Li2CO3 were thoroughly mixed and heated in air at 550'C for 6 hours. Here at 14- it was still a powdery substance. Then remix this and
When the mixture was heated and reacted at 550° C. for 12 hours, lava-like lumps were obtained. When this was crushed and classified in the same manner as in Comparative Example 1, the first yield was about 80%. The X-ray diffraction pattern of this powder was the same as in Example 1.

Moreover, the value of I211.4/I21.4 was 0.7.

A positive electrode for a battery was prepared according to a conventional method using the Li-■ oxide obtained in Examples 1 to 3 and Comparative Examples 1 and 2 as a positive electrode active material. These positive electrodes were combined with a negative electrode made of lithium metal and an electrolytic solution in which LiPFG was dissolved at 1 mol/Q in a mixed solvent of propylene carbonate and ethylene carbonate (volume ratio 1:1) to prepare a non-aqueous electrolyte secondary battery.

When the battery performance of these batteries was compared, the discharge capacities were all about the same, but the batteries using the positive electrode active materials of Examples 1 to 3 above were superior to those using the active materials of Comparative Examples 1 and 2. It was confirmed that the average potential was higher and the capacity drop during high rate discharge was smaller.

[Brief explanation of drawings]

The drawing is a graph showing an X-ray diffraction chart of a lithium-containing vanadium oxide synthesized by the production method of the present invention.

Claims (1)

[Claims] 1. Vanadium pentoxide and a lithium compound are mixed and fired to form Li_1_+_xV_3O_8_+_y (0≦x≦
0.6, -0.5≦y≦0.3), in which the lithium compounds include Li_2O, Li_2O_2, LiO
H, LiNO_3, LiI, LiCH_3CO_2, L
A method for producing a lithium-containing vanadium oxide, which comprises using a lithium compound selected from i_2C_2O_4 or a hydrous compound thereof, and subjecting the vanadium pentoxide and the lithium compound to a solid phase reaction at a firing temperature of less than 500°C. 2. Mix vanadium pentoxide and lithium compound and sinter to form Li_1_+_xV_3O_8_+_y (0≦x≦
0.6, -0.5≦y≦0.3), using Li_2CO_3 as the lithium compound,
After pre-calcining at a temperature of 00°C, it is remixed and heated to 600°C.
The above vanadium pentoxide and Li are main fired at a temperature below ℃.
A method for producing a lithium-containing vanadium oxide, which comprises performing a solid phase reaction with _2Co_3.