JPH0380119A - Electrode of cell - Google Patents

Abstract

PURPOSE:To obtain an electrode of a cell using mass-producible copper molybdenum sulfide at a low cost by reducing a solid precursor obtd. from ammonium thiomolybdate and copper halide under heating and using produced copper molybdenum sulfide as a base. CONSTITUTION:Ammonium thiomolybdate and copper halide are mixed and brought into a reaction in an org. solvent to form a precursor and the org. solvent as a medium is removed by evaporation. The resulting solid precursor is reduced under heating in an atmosphere of gaseous hydrogen to produce copper molybdenum sulfide and an electrode of a cell based on the sulfide is obtd. The copper molybdenum sulfide means copper molybdenum sulfide having so-called chevrel phase and is a compd. represented by the formula (where x is 1.5-4 and y is 0-0.4). Ammonium tetrathiomolybdate is preferably used as the ammonium thiomolybdate because oxygen is prevented from entering the product.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to battery electrodes. For more details,
The present invention relates to a battery electrode characterized in that it uses copper molybdenum sulfide produced by mixing and reacting ammonium thiomolybdate and copper halide to obtain a precursor and reducing the precursor.

[Prior art and problems to be solved by the invention] Chevrel phase compounds, whose general formula is MXMO6Sll (where M is a metal), are three-dimensional compounds with large oven channels synthesized by Chevrel et al. in 1971. , has a structure in which the third component metal M enters the gaps between the Mo6SB clusters.

This Chevrel phase compound shows specific properties for superconductivity, and copper molybdenum sulfide in which the metal M is Cu,
It is attracting attention because it has a relatively high superconducting transition point. Also,
Copper molybdenum sulfide is attracting attention as an electrode material for secondary batteries because it has the property that copper ions that enter the gaps between Moa5a clusters are extremely mobile.

A general method for producing copper molybdenum sulfide is to directly react an elemental metal or/and metal sulfide with elemental sulfur in a sealed tube made of glass or quartz.For example, (a) copper sulfide , molybdenum disulfide, and elemental sulfur were vacuum-sealed in a sealed quartz tube and heated at 1000"C for 100%
Time heating method [Toru Inoue, Electrochemistry, 5481.2
(1986) ), (b) Powders of metallic copper, metallic molybdenum, and elemental sulfur were directly blown into a sealed quartz tube by one person.
Heat this at 400° overnight, then at 1000°C for 2 hours.
Heated for 1 day, then heated to 1100°C for 30 minutes. 5 methods (K, Y, Cheun (Het, al,; Mat,
Res, Bull, 151717 (1980))
(C) Copper sulfide, molybdenum disulfide, and metal molybdenum were placed in a sealed quartz tube under vacuum for 3 to 4 hours, heated at 400°C overnight, and then heated at 1000°C for 21 hours. ,
The contents were taken out and crushed, and this was placed in a sealed quartz tube again under vacuum J for one person at +000°C using the crushing method [S, Yamamoto et al.
l,;Mat,Res,Bull,,181.31.1
(1983) ], (d) Each powder of metallic copper, metallic molybdenum, and car body sulfur was vacuum sealed in a sealed quartz tube, and heated at 440°C for 48 hours while shaking every 4 to 6 hours. Next, heating at 1000'C for 24 hours (,1
, Mizusaki et, al.; 5olid 5
tate Tonics, Earthworks 293 (1984))
etc. have been reported.

Therefore, evaluation of properties as a battery electrode has been limited to those obtained by two-way methods.

However, these methods require a long time to manufacture, and they all use a sealed quartz tube as a reaction vessel, but during the heating process, the inside of the sealed quartz tube is pressurized by the atmospheric pressure of the reacting elemental sulfur. If the heating speed to the processing temperature is too high, there is a risk that the seal will burst, and if it is too small, it will take more time to manufacture.

Further, in order to prevent the sealed tube from bursting, the volume of the sealed tube is limited to about 100 to 500 m1 at most, making mass production difficult. Furthermore, the quartz sealed tube must be broken each time to take out the contents.

Therefore, due to these factors, there is a problem in that the manufacturing cost I. is extremely high.

Further, each powder of metallic copper, metallic molybdenum, and elemental sulfur was heated for 6 to 2 hours at a temperature of 500 to 700'C in a sealed quartz tube.
After heating for 4 hours to form a precursor sulfide and pulverizing the precursor sulfide, the mixture was heated again in a sealed quartz tube to a temperature of 900 to 100'.
There is also a method of heating for 24 to 120 hours at a temperature of
(method described in issue).

However, this method also uses a sealed tube made of stopcock quartz, so although the problem of the sealed tube bursting during the production of copper molybdenum sulfide can be avoided, it requires a certain amount of time for production. Furthermore, the problems of high cost I and difficulty in mass production since the sealed tube must be broken each time to take out the contents have not been solved.

Therefore, commercializing copper molybdenum sulfide obtained by these manufacturing methods as a battery electrode has been impossible in the past in terms of production volume and cost.

[Means for Solving the Problems] The inventors of the present invention solved the above-mentioned problems and as a result of intensive studies to manufacture battery electrodes using copper molybdenum sulfide that can be mass-produced at low cost. A precursor is produced by mixing and reacting thiomolybdate ammonium salt and copper halide in an organic solvent, and the precursor solid obtained by evaporating the organic solvent as a medium is heated in a hydrogen gas atmosphere. If the method involves heating and reducing, it is a normal chemical process and can be mass-produced, and since it does not require special reaction equipment such as quartz mains and J-tubes, the manufacturing cost is also low. It was discovered that battery electrodes manufactured using the copper molybdenum sulfide manufactured in 1997 showed the same performance as those manufactured using ordinary quartz sealed tubes, and this led to the completion of the present invention.

That is, the present invention involves mixing and reacting thiomolybdate ammonium salt and copper halide in an organic solvent to produce a precursor, and then evaporating and distilling off the organic solvent as a medium to obtain the precursor solid. , relates to a battery electrode characterized in that it uses copper molybdenum sulfide produced by heating and reducing in a hydrogen gas atmosphere.

[Detailed disclosure of the invention]

The present invention will be explained in more detail.

The copper molybdenum sulfide used in the present invention refers to the so-called Chevrel phase copper molybdenum sulfide, which has the form Cu
xMobSe-y (x=1..5-4, y=O~0
．． Refers to the compound represented by 4).

The "precursor" as used in the present invention is a solid product obtained by mixing and reacting thiomolybdate ammonium salt and copper halide in an aqueous solvent, and then evaporating and distilling off the organic solvent.

The ammonium thiomolybdate salt used in the present invention is a variety of salts in which the oxygen atom in ammonium molybdate is replaced with a sulfur atom, such as ammonium dioctudithiomolybdate, The. Among them, ammonium osimolybdate, ammonium tetrathiomolybdate, etc. are preferred, and ammonium tetrathiomolybdate is preferable because it prevents the contamination of oxygen.

Copper halides include cuprous fluoride, cupric fluoride, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, and cupric iodide. Although copper can be used, cupric chloride is preferred because it is readily available and inexpensive.

In the present invention, the ratio iJ of thiomolybdate ammonium salt and copper halide, the molar ratio charged to the container, Cu
/Mo=0.25 to 0.67.

The organic solvent used in the present invention is one that can dissolve at least one of the above-mentioned thiomolybdate ammonium salt and copper halide, but these organic solvents may be alcohols, carbons, esters, etc. , nitriles, adands, halogenated hydrocarbons, amino alcohols, etc. To describe this more specifically, alcohols include methanol, ethanol, butanol, etc., ketones include acetone, methyl ethyl ketone, etc., esters include ethyl formate, ethyl acetate, etc., and nitriles include acetonyl-1-lyl, etc. As an amide, ace I
- Examples of halogenated hydrocarbons such as amide and diethylformamide include 1-lichloroethylene and trichloroethane, and examples of 71-noalcohols include ethanolamine. Incidentally, these organic solvents may be used alone or in combination of two or more.

The amount of organic solvent used is not particularly limited as long as it dissolves either ammonium thiomolybdate salt or copper halide, but it is not economical to use more than 100 mQ of organic solvent. Preferably, the amount of thiomolybdate ammonium salt is 2 g or more and the copper halide is 1 g or more.

In addition, when mixing and reacting thiomolybdate ammonium salt and copper halide in an organic solvent, each of them may be dispersed and dissolved in the organic solvent in advance, and then both may be mixed. A method of adding thiomolybdate ammonium salt and copper halide may also be used.

In the present invention, the aqueous solvent may be used as is, but it is preferable to blow nitrogen gas in advance to remove dissolved oxygen.

The mixed solution of ammonium thiomolybdate, copper halide, and organic solvent charged in the container can be heated and stirred as is, but in order to prevent oxidation, the ammonium thiomolybdate and Thiomolybdate ammonium salt and copper halide are mixed and reacted by heating and stirring while blowing nitrogen gas into the Ifa solvent containing copper halide or while flowing nitrogen gas through the gas phase of the container. It doesn't matter.

There are no particular limitations on the mixing/reaction temperature, but the mixing/reaction temperature is carried out at room temperature to a temperature below the boiling point of the organic solvent.

Therefore, it is preferable that the container is equipped with a reflux condenser.
The organic solvent evaporated during the mixing and reaction is condensed in this reflux condenser and recycled into the container.

There are no particular limitations on the mixing/reaction time, but it is usually 0.
．． You can choose an appropriate time between 5 and 10 hours.

The liquid after the completion of the mixing and reaction is then heated to evaporate and distill off the organic solvent used as a medium.

The organic solvent may be evaporated or distilled off under reduced pressure using, for example, a rotary evaporator, or simply under normal pressure.

The thus obtained solid precursor is heated and reduced in a hydrogen gas atmosphere to obtain Chevrel phase copper molybdenum sulfide. Note that this hydrogen gas for reduction does not necessarily have to be 100% hydrogen gas, and may be hydrogen gas diluted with an inert gas such as a nitrogen gas cap.

Reduction methods include a batch method in which a closed container containing the precursor and hydrogen gas is heated, and a semi-continuous method in which hydrogen gas is continuously supplied into the heating furnace while the precursor is charged into the heating furnace. For example, a continuous method is employed in which a precursor and hydrogen gas are continuously supplied to a fluidized bed apparatus.

The reduction temperature is selected in the range of 800-1500°C.

If the reduction temperature is less than 800°C, the rate of reduction to fluorine will be slow, which is not practical, while if it exceeds 1500°C, there will be restrictions on the material of the device, which is not preferable. The reduction temperature is therefore selected within a dual temperature range.

The reduction time cannot be determined centrally because it is determined by a combination of the set reduction temperature, the concentration of hydrogen in the reducing gas, and the amount of hydrogen gas supplied if the reduction method is semi-continuous or continuous. do not have.

However, when the resulting copper molybdenum sulfide is analyzed using an X-ray diffraction device, a peak of metal molybdenum appears in addition to the peak of Chevrel phase sulfide, and conversely, when the reduction is insufficient, In this case, the molybdenum disulfide peak remains in the Chevrel phase sulfide peak. Therefore, from the analysis results using an X-ray diffraction device, @iJ!
What is necessary is to determine the return conditions such as time.

The term "battery electrode" as used in the present invention refers to an electron conductor or a semiconductor provided for the purpose of forming a positive electrode and a negative electrode with an electrolyte material interposed therebetween for the purpose of discharging or charging the battery.

When forming a battery electrode using Chevrel phase copper molybdenum sulfide produced from ammonium thiomolybdate salt and copper halide, the produced product can be used alone, or RbaCII++, ], CI
+i, Rb1-, Cu4]+, 5C1s, s, etc. may be mixed with a solid electrolyte and then compressed or molded by adding additives.

There is no particular restriction on the mixing ratio of Chevrel phase copper molybdenum sulfide (hereinafter simply referred to as copper molybdenum sulfide) and the solid electrolyte, but it is preferable that the mixing ratio of copper molybdenum sulfide is at least 10% or more.

To mold copper molybdenum sulfide alone or a mixture of copper molybdenum sulfide and a solid electrolyte, add additives and a solvent and make a sheet using, for example, a doctor blade method, or use a normal pressure molding machine to form a sheet of several tens of kg. The molding may be carried out at a pressure of 1/cm2 to several t/cm. In this case, an appropriate amount of the additives described below may be added.

In the present invention, additives used in the above molding include polyisoprene, SBR, NBR, urethane rubber, chloroprene rubber, polyester rubber, epichlorohydrin rubber, silicone rubber, polystyrene, polyvinyl chloride, ethylene ethyl acetate. Copolymers, polyesters, epoxy resins, phenolic resins and mixtures thereof are used.

The proportion of the additives mentioned above is not particularly limited, but from the viewpoint of conductivity it is preferably within 30%. Furthermore, a conductive substance such as carbon blank or graphite may be added for the purpose of increasing the conductivity of the electrode.

There is no particular restriction on the proportion of carbon blank or graphite added. However, in consideration of the moldability and performance of the electrode, 5 to 60% is suitable.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist thereof remains unchanged.

Example 1 500 m of acetonitrile was added to a fourth flask with an internal volume of 11 equipped with a stirrer, a gas blowing tube, and a reflux condenser.
1 and 16 g of ammonium tetrathiomolybdate were charged, and the mixture was stirred while blowing nitrogen gas to dissolve the ammonium tetrathiomolybdate.

Next, put 400 ml of acetonitrile in another flask, stir while blowing nitrogen gas, add 2.76 g of cupric chloride to prepare a dissolved solution, and add this to the fourth flask mentioned above. (Preparation molar ratio Cu/Mo
=0.33).

Thereafter, the temperature was raised to reflux temperature while blowing nitrogen gas into the fourth flask, and the mixture was stirred at this temperature for 6 hours to react. After the reaction is complete, the reaction solution is cooled to room temperature, charged into a rotary evaporator, sucked with a vacuum pump, and heated under reduced pressure to completely evaporate and distill off acetonitrile, resulting in a solid product. 18.4IXi' of the precursor;
It was. Note that the yield of the precursor was 98% based on molybdenum.

(Reduction of Precursor) 6 g of the precursor obtained above was placed in an Al ≧ Na~1. The temperature was raised to C. After raising the temperature, while maintaining the temperature, the circulating gas is changed from nitrogen gas to a mixed gas of nitrogen gas and hydrogen gas (hydrogen gas concentration 50% by volume).
) and reduced the precursor for 4 hours.

After the reduction was completed, the circulating gas was switched to nitrogen gas again, and the reactor was cooled to room temperature. After cooling, the contents of the alumina bowl 1 were taken out, and 3.08 g of product was obtained. When this product was analyzed using an X-ray diffractometer, the X-ray diffraction diagram shown in FIG. 1 was obtained, and it was confirmed from the diagram that a single Chevrel phase compound was produced. Also, this
The ray diffraction diagram was the same as the X-ray diffraction diagram of the product obtained in Reference Example 1 (copper by conventional sealed tube method: production of liveden sulfide), which will be described later. The yield upon reduction was 97%, and the total yield was 95% (all based on molybdenum).
.

(Production of solid electrolyte) J, EIectrochem, Soc, 1261654
(1979), using CuCl with a purity of 99.9% and CuCl with a purity of 99.9%.
After sufficiently drying 1 lbcl of 9% Cul and 99.9% purity, 9.0 g, 13.3 g, and 4.9 g of each were weighed and vacuum-sealed in a glass sealed tube.

As a heating method, the reaction was carried out at 200°C for 17 hours,
After that, annealing is performed at 130°C to form a solid electrolyte Rb4.
Cu+ 617CI + 3 was produced.

(Formation of battery) 2 g of copper molybdenum sulfide obtained by reducing the precursor and
(Production of solid electrolyte) Rb4Cu+617c obtained in
After mixing 32 g of L.
? -1500) was thoroughly kneaded in a mortar and applied onto a Teflon plate using an applicator.

After coating, the toluene was dried to produce a sheet-like electrode with a thickness of about 100 μm. A disk with a diameter of 13 mm was cut out from the sheet and used as an electrode disk.

Next, 0.7 g of the solid electrolyte was press-molded at a pressure of 500 kg/cm 2 to produce a solid electrolyte disk with a diameter of 13 mm. The electrolyte was sandwiched between two electrodes, and the one using a graphite sheet as a current collector was used as the positive electrode, and the one using lPl foil was used as the negative electrode.

(Measurement of battery electrode performance) After charging the battery produced in the above (battery turbulence) until the amount of copper in the copper chevret of the positive electrode reached 0.62 μm,
The discharge characteristics were investigated by discharging at a constant current. As a result of measuring the positive electrode capacity when discharging to 300mV, it was 24.6m/
lhr/g, manufactured by the quartz sealed tube method of Reference Example 1,
For electrodes manufactured using copper molybdenum sulfide,
It showed good battery electrode characteristics that were approximately equal to 25.0 mAh/g.

The battery performance is determined by Hokuto Denko's battery charge/discharge test device +1.
Measurement was performed using J-201B model.

Reference Example 1 13.3 g of electrolytic copper powder with a purity of 99.7% and a particle size of 50 particles as metallic copper, a purity of 99.9% and a particle size of 5
26.1 g of elemental sulfur powder having a particle size of 6 Ω, Og, and a purity of 99.9% and a particle size of 50 mesh were weighed and mixed. (Molar ratio Cu:Mo:S = 2:6:7.8) The above mixture was charged into a sealed quartz container with an internal volume of 150 m1 made from a quartz tube with an outer diameter of 34 mm and an inner diameter of 28 mm, and then, While heating this sealed tube to a temperature of 60°C with a heater, air inside the sealed tube is pumped out using a vacuum pump] T
It was evacuated to a pressure of orr or less and melt-sealed.

This sealed tube was heated to 60°C in an electric furnace at a heating rate of 20°C/h.
The temperature was raised to 0°C and incubated at this temperature for 12 hours to produce a precursor sulfide. After the reaction is complete, the sealed tube is allowed to cool naturally, the contents are taken out, and the total amount of this precursor sulfide is reduced to 115
It was crushed in a mortar to become Metsuyubas.

Next, this pulverized precursor sulfide was charged into a sealed tube with the same quartz front as that used for producing the precursor sulfide, and this sealed tube was heated to a temperature of 60 ° C with a heater. Then, the air in the sealed tube was evacuated to a pressure of Torr or less using a vacuum pump, and the tube was fused and sealed.

This sealed tube was placed in an electric furnace at a heating rate of 100'C/h.
The temperature was raised to 000'C, and the reaction was continued at this temperature for 24 hours.

After the reaction was completed, the sealed tube was allowed to cool naturally, and the contents were taken out and analyzed using an X-ray diffraction device. It was confirmed that

Examples 2 to 4 Using the equipment used in Example 1, under the conditions shown in Table 1,
A precursor was produced and reduced in the same manner as in Example 1 to obtain copper molybdenum sulfide.

That is, in the fourth flask used in Example 1, there were the types shown in Table 1. 500 mR each of 4 medium and 16 g each of ammonium tetradiomolybdate were charged and stirred while blowing nitrogen gas.

Next, in separate flasks, add 4 quarts each of the types of organic solvents shown in Table 1.
00 was prepared, stirred while blowing nitrogen gas, and added copper halide of the type shown in Table 1 in the amount shown in Table 1 to prepare a solution, which was added to the fourth flask mentioned above. .

Thereafter, the mixture was stirred while blowing nitrogen gas into the fourth flask, and mixing was carried out at the temperature and time shown in Table 1. After the mixing was completed, the liquid was cooled to room temperature.

Next, this reaction solution is charged into a rotary evaporator, sucked with a vacuum pump, and heated under reduced pressure to completely evaporate and distill off the organic solvent. I got it.

6 g of each of the precursors obtained above was put into an alumina boat in the same manner as in Example 1, and then charged into a tube furnace. The temperature was raised to After raising the temperature, the precursor was reduced under the conditions shown in Table 1 using hydrogen gas at the concentration shown in Table 1 to obtain a product with a volume not shown in Table 1.

When each of these products was analyzed using an X-ray diffraction apparatus in the same manner as in Example 1, the X-ray diffraction pattern was similar to that in Example 1, and it was identified as copper molybdenum sulfide in a single Chevrel phase.

(Battery Formation) Electrodes were molded from the copper molybdenum sulfide produced in Examples 2 and 3 shown in Table 1 under the conditions produced in Example 1 (Battery Formation). Next, as a result of examining the discharge characteristics under the measurement conditions of Example 1 (measurement of battery electrode performance), as shown in Table 1, the electrode manufactured using the copper molybdenum sulfide of Reference Example 1 and Almost the same good results were obtained.

C Effects of the Invention] As explained in detail above, the battery electrode of the present invention is produced by mixing and reacting ammonium molybdate salt with copper halide in an organic solvent to obtain a precursor, and then exposing the precursor to a hydrogen gas atmosphere. It was produced by using the copper molybdenum sulfide obtained by reducing the copper molybdenum sulfide.

Moreover, there is no danger of the conventional manufacturing method using sealed quartz tubes, and even if the electrode is manufactured using copper molybdenum sulfide using a manufacturing method suitable for mass production, As shown in the reference examples, the quality of the product is equivalent to that of an electrode manufactured using copper molybdenum sulfide, which was achieved using a conventional method using a sealed tube, so it is suitable as an electrode for secondary batteries. It is used.

The present invention has various great effects as described above, and in particular, since it uses copper molybdenum sulfide which can be mass-produced, it is possible to provide a large quantity of inexpensive battery electrodes, so the role of the present invention in industry is extremely important. There is something.

[Brief explanation of drawings]

Figure 1 is an X-ray diffraction diagram of copper molybdenum sulfide of the present invention obtained in Example 1, and Figure 2 is an X-ray diffraction diagram of copper molybdenum sulfide obtained in Reference Example 1 (conventional sealing method). It is an X-ray diffraction diagram of.

Claims (1)

[Claims] 1) A precursor is produced by mixing and reacting thiomolybdate ammonium salt and copper halide in an organic solvent, and the precursor solid obtained by evaporating and distilling off the organic solvent as a medium is heated with hydrogen gas. A battery electrode made mainly of copper molybdenum sulfide, manufactured by heating and reducing in an atmosphere.