JP2003208897A - Lithium battery and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is hard to take a large current and that the charge and discharge cycle characteristic is low because single sulfur is an insulating material and hinders electron conductivity and ion conductivity and the problem that it is hard to mix with the conductive agent such as a carbon because the single sulfur is hard to be dissolved in the solvent except carbon bisulfide (CS<SB>2</SB>). <P>SOLUTION: Sulfur is heated for melting, and mixed with the solid electrolyte and the conductive agent to form a positive electrode having high electron conductivity and high ion conductivity. This positive electrode is used for a lithium battery, and the battery is formed of the positive electrode, a negative electrode and the electrolyte chemically stabilized in relation to the positive electrode and the negative electrode and for moving the ion between these electrodes. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lithium battery including a positive electrode, a negative electrode and a non-aqueous electrolyte.

[0002]

2. Description of the Related Art In recent years, with the development of mobile communication equipments and portable electronic equipments, the demand for their power sources has become very large. Lithium secondary batteries have high electromotive force and high energy density, and are therefore widely used as power sources for portable electronic devices. However, with the reduction in size and weight of portable electronic devices, the demand for higher energy density of batteries is also increasing, and the advent of new electrode materials having higher energy density is desired. On the other hand, the drive voltage of the equipment is also decreasing, and a situation where a voltage of 2 to 2.5 V can be used as a battery is also emerging. Against this background, various efforts are being made. In particular, since increasing the energy density of the positive electrode and the negative electrode active material directly leads to increasing the energy density of the battery itself, efforts for material development are being actively carried out for each of the positive electrode and the negative electrode.

Among them, much research has been carried out on lithium batteries using high capacity and low cost elemental sulfur as a positive electrode material. The followings are the researches on the major sulfur batteries so far. U.S. Pat. No. 5,523,179 proposes using elemental sulfur for the positive electrode. That is, it is said that this battery has an operating voltage of 2 V and a high energy density of 100 to 800 Wh / kg can be expected using a metallic lithium negative electrode, but since it can be charged and discharged only at high temperature and in a molten state, it is practically used. It has not been realized. In US Pat. No. 4,833,048 and US Pat. No. 5,516,598, Dejonghe et al. Invented a secondary battery using an organic sulfur compound. This sulfur compound is most simply expressed as M ⁺ − ⁻ S−R−S ⁻ −M ⁺ (R is an aliphatic or aromatic organic group, S is sulfur, M ⁺
Is a proton or a metal cation). This compound bound to each other via an S-S bond by the electrolytic ^{oxidation, M + - - S-R} -S-S-R-S-S-R-S - polymers in the form such as -M ⁺ . The polymer thus produced returns to the original monomer by electrolytic reduction. This reaction is used for a charge / discharge reaction to obtain a secondary battery. A. Skotheim et al. And Moltech used poly-carbon sulfides represented by the general formula (C ₂ S _x ) _n (2 ≦ x ≦ 100, n ≧ 2). Invented a secondary battery (US Pat. No. 5,441,8)
31 and U.S. Pat. No. 5,529,860).
This polycarbon sulfide has a structure in which carbon is a skeleton and sulfur atoms are side chains. A secondary battery was made by utilizing the SS bond / dissociation reaction of the sulfur atom.

On the other hand, as a high capacity material for the negative electrode, lithium is used.
Um-containing composite nitrides are expected. Nitriding of lithium
As the material, lithium nitride (Li
₃N) has been well studied. This lithium nitride is
Since it has on-conductivity but no electron conductivity,
Instead, it has been considered as an electrolyte. However, recently L
i ₃Addition of other metal components to N to impart electronic conductivity
In addition, so-called lithium-containing composite nitride is used as the electrode active material.
I understand that it works. This lithium-containing composite nitride
The researches on the objects are as follows. Lithium-containing composite
Nitride is V.W.Sachsze, et a1., Z. Anorg. Chem. (1949)
p278 and T. Asai, et al., Mat. Res. Bull. vol. 16 (19
84) Reported in p1377. Li₃Fe was added to N
Li₃FeN₂(M, Nishijima, et al., J. Solid State Ch
em..vol.113, (1994) p205, Li₃L in which Mn is added to N
i₇MnN_Four(M. Nishijima, et al., J. Electrochem. So
c. Vol. 141. (1994) p2966., Li₃L with Co added to N
i_3-xCo_xN (M.Nishijima, et al., Solid State Ionic
s vol.83 (1996) p107 Same as T. Shoudai, et al., Soli
d State Ionics vol.86-88, p785 (1996)).
Also, as a patent application using this kind of material as an electrode material
Are disclosed in JP-A-7-78609 and JP-A-7-3207.
No. 20, JP-A-9-22697, etc. are known.
ing.

[0005]

However, the above sulfur-based battery has the following problems. That is,
Since elemental sulfur is an insulator, it has poor electron conductivity and ionic conductivity, and the redox reaction is slow at room temperature, making it difficult to extract a large current. Further, there is a problem that the charge / discharge cycle characteristics are poor when the elemental sulfur is used as it is. Further, elemental sulfur is difficult to dissolve in a solvent other than carbon disulfide (CS ₂ ), and the amount of dispersed solvent is small, so that it is difficult to mix it with a conductive agent such as carbon. Also, carbon dioxide having a low boiling point and a low flash point (C
It is necessary to use S ₂ ) as solvent. Further, the polycarbon sulfide represented by the general formula (C ₂ S _x ) _n described above is complicated to synthesize. The cost is also high. Furthermore, organic sulfur compounds are mainly disulfides, and high capacity cannot be realized. Further, in any of the above-mentioned sulfur-based batteries, lithium metal is used for the negative electrode, so that commercialization of the battery was difficult.

The lithium-containing composite nitride has the following problems. That is, the lithium-containing composite nitride, unlike graphite materials, alloys, and metal oxides, is a battery starting from lithium desorption. Therefore, when combined with a positive electrode such as LiCoO ₂ , pretreatment such as lithium desorption treatment is required in advance.

An object of the present invention is to solve the above problems in the prior art and provide a high capacity secondary battery.

[0008]

According to the present invention for solving the above-mentioned conventional problems, the general formula (Li _x S) _n (0 <x ≦ 1.5,
n is an integer of 1 or more), and a positive electrode having a compound represented by the following:
General formula Li _3-y M _y N (0.2 ≦ y ≦ 0.8, M is Ti,
A compound represented by at least one element selected from V, Cr, Mn, Fe, Co, Ni, and Cu) or
A lithium battery having a negative electrode containing a solid solution of Sn and Si, an intermetallic compound of Sn or Si, or an oxide of Sn or Si, and an electrolytic solution was prepared. further,
When the positive electrode mixture weight is 100% by weight, the general formula (Li
_x S) _n (0 <x ≦ 1.5, n is an integer of 1 or more) is 60 to 98% by weight, the solid electrolyte is 20 to 1% by weight,
And the electric conductor has 20 to 1% by weight, and the (Li _x S) _n
A lithium battery having a solid electrolyte on the particle surface of the compound represented by and a conductor controlling the electron conductivity in the positive electrode was obtained.
Further, the solid electrolyte is Li ₂ S-SiS _{(2 + a)} (a is Li ₃ P
At least one selected from O ₄ , LiI, and Li ₄ SiO ₄ ), Li ₂ S-
A lithium battery having at least one selected from P ₂ O ₅ , Li ₂ SB ₂ S ₅ , and Li ₂ SP ₂ S ₅ -GeS ₂ was used. Furthermore, the conductor that controls the electron conductivity in the positive electrode is a carbon material having conductivity,
A lithium battery containing at least one selected from polyaniline, polypyrrole, polythiophene, and polyacetylene was prepared. Furthermore, the general formula (Li _x S) _n (0 <x ≦
The average particle shape of the compound represented by 1.5 and n is an integer of 1 or more) is a lithium battery having a particle shape of 5 to 100 μm.

Further, the general formula (Li _x S) _n (0 <x ≦ 1.
5, n is an integer of 1 or more), a positive electrode having a compound represented by a heating process, a dissolution process, a solid electrolyte, a process of mixing with a conductor that controls the electronic conductivity in the positive electrode Manufacturing method.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention produced a positive electrode for a lithium battery having high electrochemical activity by mixing elemental sulfur with a conductive agent and a solid electrolyte at the molecular level. Furthermore, a high-capacity secondary battery was realized by using the positive electrode and the negative electrode having the lithium-containing composite nitride.

That is, in the present invention, a conductive agent such as carbon is added to the surface of the simple substance sulfur particles to improve the electron conductivity, and further, a solid electrolyte is added to the surface of the simple substance sulfur particles to improve the ionic conductivity. By obtaining elemental sulfur having high electrochemical activity and using it as a positive electrode active material, a high capacity secondary battery was obtained.

The highly dispersed mixing of the elemental sulfur with the conductive agent and the solid electrolyte was realized by heating and melting the elemental sulfur at high temperature and mixing the conductive agent and the solid electrolyte therein. Also,
The reaction of the elemental sulfur with the conductive agent and the solid electrolyte is simple.

That is, in the present invention, the compound represented by the general formula (Li _x S) _n (0 <x ≦ 1.5, n is an integer of 1 or more) dissolved in the above-mentioned general formula (Li _x S) _{n is used.} When in the compounds represented is 100 wt% of the positive electrode mixture by weight, 60 to 98%, the solid electrolyte is 20 to 1%, and the conductor are mixed in a weight ratio of 20 to 1%, the formula (Li _x The conductive agent and the solid electrolyte are present on the surface of the particles of the compound represented by S) _n , and the conductive material and the solid electrolyte are used for the positive electrode for a lithium battery using an active material having a uniformly distributed shape. The positive electrode is composed of a compound represented by the general formula (Li _x S) _n (0 <x ≦ 1.5, n ≧ 1), a solid electrolyte, and a conductor that controls electronic conductivity in the positive electrode. As the conductor, for example,
Graphite, a conductive carbon material such as carbon, a conductive polymer or the like is preferable, and as the conductive polymer, for example, polyacene, polyacetylene, polyaniline, polypyrrole, a polymer or a polymer thereof having a conjugated structure such as polythiophene, A derivative having a side chain such as butyl is preferable. Further, as the solid electrolyte, Li ₂ S-SiS _{(2 + a)} (a is at least one selected from Li ₃ PO ₄ , LiI, Li ₄ SiO ₄ ), Li ₂ SP ₂ O ₅ , Li ₂ SB ₂ S ₅ , Li ₂ SP ₂
In addition to S ₅ -GeS ₂ , sodium / alumina (Al ₂ O ₃ ), amorphous, low phase transition temperature (Tg) polyether, amorphous vinylidene fluoride copolymer, blend of different polymers, polyethylene oxide, poly An ion conductive gel polymer electrolyte in which a low molecular weight non-aqueous solvent such as ethylene carbonate or propylene carbonate is added to acrylonitrile, a copolymer of ethylene and acrylonitrile, or a crosslinked polymer, and an electrolyte salt is added thereto is preferably used. Then, it is also preferable to add, for example, polyvinylidene fluoride, amorphous polyether, or polyacrylamide as a binder into the positive electrode active material. The electrolyte salt comprises a halogen salt of an alkali metal such as lithium, sodium or potassium or an alkaline earth metal such as magnesium, or a salt of a fluorine-containing compound represented by perchlorate or trifluoromethanesulfonate. At least one selected from the group is preferable, and specific examples of such an electrolyte salt include, for example, lithium fluoride, lithium chloride, lithium perchlorate, lithium trifluoromethanesulfonate, lithium tetrafluorofluoride, and bistrifluoromethyl. Examples thereof include lithium sulfonylimide, lithium thiocyanate, magnesium perchlorate, magnesium trifluoromethanesulfonate, and sodium tetrafluoroborate.

In addition to the nitrogen compound of lithium, the negative electrode is
Alkali metal-inserted carbons such as lithium, tin (Sn) and composites with carbon or other metals, polymers having conjugated structures such as polyacene, polyacetylene, polyaniline, polythiophene, polypyrrole and their methyl, butyl, benzyl, etc. Examples thereof include conductive polymers made of derivatives having a side chain.

[0015]

EXAMPLES Examples of the present invention will be described below. In this example, first, a method for manufacturing a positive electrode is described, and then, a lithium battery including a manufactured positive electrode, a negative electrode, and an electrolytic solution is described.

Example 1 A sulfur positive electrode was synthesized as follows.

A predetermined amount of elemental sulfur (S) (molecular weight;
Tohka Chemical Co., Ltd., conductive carbon (den
Kablack Denki Kagaku Kogyo), Li as solid electrolyte₂S
-SiS ₂-Li₃PO_FourWas added and mixed well to obtain a positive electrode powder. Single sulfur
Table 1 shows the mixing ratio of yellow, the conductive agent, and the solid electrolyte.

[0018]

[Table 1]

Next, using the positive electrode powder prepared above,
A positive electrode plate was produced by the following method. The positive electrode powder was mixed with polyvinylidene fluoride (KF polymer 9130, manufactured by Kureha Chemical Industry Co., Ltd.) as a binder at a weight ratio of 10: 1. After mixing well, cast this mixture on an aluminum foil current collector.
Vacuum drying was performed at ℃ for 1 hour. After drying, this is 13.5m in diameter
It was punched out on a disk of m to obtain a positive electrode plate. At this time, the thickness of the electrode plate was adjusted so that the weight was 13 mg or less.

Next, a method for synthesizing the gel electrolyte used as the electrolyte will be described. As the gel electrolyte, 20.7 g of a mixed solution of propylene carbonate and ethylene carbonate (manufactured by Sollite Mitsubishi Chemical Co., Ltd.) in which 1 M of LiBF ₄ was dissolved at a volume ratio of 1: 1 was added to 3.0 g of polyacrylonitrile.
(Manufactured by Aldrich), and heated at 140 ° C. for 5 minutes on a stenbat to cause gelation to obtain a gel electrolyte. The thickness of this gel electrolyte was 0.3 mm.

Metal lithium (thickness: 300 μm, made by Asahi Tohkin Co., Ltd.) was used as a counter electrode for the positive electrode plate prepared by the above method to prepare a coin-type battery, and its characteristics were evaluated. The structure of the coin-type battery used for evaluation is shown in FIG. Next, a battery manufacturing procedure is shown below. First, the positive electrode plate (11) is attached to the case (1
It is placed on the current collector (13) provided in 2), then lithium metal is pressure-bonded to the inside of the case with the sealing ring attached to the peripheral edge, and the gel electrolyte (14) is placed on this, and further on top of this. A separator made of a porous polyethylene sheet (Celgard Asahi Kasei) (15) was installed in the above, and this was caulked and sealed with an interlocking press to produce a coin battery. For the coin battery produced in this way, the current value per unit area was 0.1 mA, the voltage range was
A constant current charge / discharge was performed at 1.5V to 4.0V and the characteristics were evaluated.
The results are shown in Table 2. Here, the discharge capacities of the second cycle and the fifth cycle are shown.

[0022]

[Table 2]

As is apparent from Table 2, when the positive electrode mixture weight is 100% by weight according to the preparation method of the example, the sulfur content is 60%.
Below, 98% or more, solid electrolyte and conductive agent 20%
As described above, in the case of the composition within the range of 2% or less, the capacity is small, and preferable characteristics cannot be obtained. Therefore,
60% to 98% sulfur and 2% solid electrolyte
It was found that the preferable characteristics cannot be obtained outside the range of 0 to 1% and the weight ratio of the conductor of 20 to 1%.

The reason for this is that the solid electrolyte and the conductive agent are uniformly distributed on the surface of the sulfur particles which are insulators, and the structure is such that a sufficient conductive path from the current collector to the sulfur particles can be obtained.
It is considered that the discharge capacity and cycle characteristics were improved.

The positive electrode mixed weight is 100% by weight, sulfur is 60 to 98%, solid electrolyte is 20 to 1%, and conductor is
It was confirmed that the positive electrode plate in a weight ratio range of 20 to 1% had a structure in which the solid electrolyte and the conductive agent were present on the surface of the sulfur particles or on the surface of the particles, as shown in FIG. From these results, it was found that the structure in which the solid electrolyte and the conductive agent are present on the surface of the sulfur particles in the ratio in the above range leads to the improvement of the cycle characteristics of the sulfur positive electrode.

(Example 2) Sulfur carried out by the method of Example 1 was 60 to 98%, the solid electrolyte was 20 to 1%, and the conductor was
A method for producing a positive electrode having a weight ratio of 20 to 1% was studied.

Elementary sulfur (S) having a predetermined composition (molecular weight: 32
Kanto Kagaku) to N-methylpyrrolidone (Kanto Kagaku)
It was heated to 110 to 120 ° C. together with (weight ratio 1: 1). Further dissolve, add 10 g of acetylene black (Denka Black Denki Kagaku Kogyo) as a conductive agent, and further 10 g of Li ₂ S-SiS ₂ -Li ₃ PO ₄ as a solid electrolyte.
The mixture was added and mixed well to obtain a black ink-like liquid. To this black ink-like liquid, 4 g of LiBF ₄ as an electrolyte salt and 10 g of polyvinylidene fluoride (N-methylpyrrolidone solution, KF polymer 9130 manufactured by Kureha Chemical Industry Co., Ltd.) as a binder were added and mixed for 1 hour, and then an aluminum foil having a thickness of 16 μm. It was cast on the surface and then vacuum dried at 60 ° C. for 2 hours to obtain a positive electrode.

Comparative Example 1 80 g of elemental sulfur (S) (molecular weight: 32 manufactured by Kanto Kagaku) was mixed with N-methylpyrrolidone (manufactured by Kanto Kagaku) (weight ratio 1: 1). 10 g of conductive carbon (made by Denka Black Denki Kagaku Kogyo) was added as a conductive agent, and Li ₂ S-SiS ₂ -was added as a solid electrolyte.
10 g of Li ₃ PO ₄ was added and mixed well to obtain a black ink-like liquid. 4 g of electrolyte salt was added to this black ink-like liquid.
LiBF4, polyvinylidene fluoride (N-methylpyrrolidone solution, KF polymer 9130 manufactured by Kureha Chemical Industry) as a binder
After adding 10 g and mixing for 1 hour, cast on an aluminum foil with a thickness of 16 μm, then vacuum dry at 60 ° C. for 2 hours,
It was used as the positive electrode.

Comparative Example 2 80 g of elemental sulfur (S) (molecule
Amount: 32 Conductive carbon (den
Kablack Denki Kagaku Kogyo Co., Ltd.) (10 g)
Li as body electrolyte ₂S-SiS₂-Li₃PO_FourAdd 10g and mix well
Then, a black powder was obtained. 4 as electrolyte salt in this black powder
g LiBF_Four, Polyvinylidene fluoride (N-meth) as a binder
Tyrpyrrolidone solution, KF polymer 9130 Kureha Chemical Industry
10g) and mixed for 1 hour.
Cast on um foil and vacuum dry at 60 ℃ for 2 hours
It carried out and it was set as the positive electrode.

A coin-type battery was prepared using the positive electrode, the negative electrode and the electrolyte prepared in Example 2 and Comparative Examples 1 and 2, and the charge / discharge test was evaluated. The negative electrode, the electrolyte and the coin battery were prepared in the same manner as in Example 1. The charge / discharge test was evaluated on the positive electrode plate at a current value of 0.1 mA per unit area and a voltage range of 1.5V to 4.0V. The results are shown in Table 3. In Table 3, only the discharge capacities at the 2nd, 5th and 10th cycles are shown.

[0031]

[Table 3]

The positive electrodes prepared in Comparative Examples 1 and 2 showed a high discharge capacity up to the 5th cycle, but a capacity decrease was observed at the 10th cycle. The positive electrode prepared in Example 2 showed a high discharge capacity even at the 10th cycle. From the above results, it was possible to obtain higher charging / discharging characteristics in the positive electrode production method of Example 2 than in the production methods of Comparative Examples 1 and 2.

The average particle shape of the positive electrode mixture prepared in Example 2 and Comparative Examples 1 and 2 was observed. The results are shown in Table 4.

[0034]

[Table 4]

In Comparative Examples 1 and 2, the average particle shape of the positive electrode mixture was 50 to
Although it is 550 nm, the average particle shape of the mixture prepared by the method of Example 2 is 5 to 100 nm, and both the particle shape and the distribution are small. In addition, from the observation results of the positive electrode particles using a scanning electron microscope, in Comparative Examples 1 and 2, the sulfur, the solid electrolyte, and the conductive agent were not uniformly distributed, but were largely unevenly distributed. On the other hand, Example
The particles of No. 2 had a structure in which sulfur, a solid electrolyte and a conductive agent were uniformly distributed as shown in FIG. From these results, it was found that the electrode manufacturing method of Example 2 improved the dispersion of particles in the electrode.

The manufacturing method described in Example 2 was
By passing through the process of heating the sulfur and the process of dissolving it, the dispersion of the elemental sulfur, the solid electrolyte, and the conductive agent in the electrode was improved, and uniform mixing became possible. When the dispersion of the elemental sulfur, the solid electrolyte, and the conductive agent is improved, the electron conductivity in the positive electrode plate is improved, and the elemental sulfur can be efficiently reacted. In the mixing that does not go through the conventional heating and melting process performed in the comparative example, it is difficult to mix the elemental sulfur, the conductive agent, and the solid electrolyte in a high dispersion. On the other hand, when the process of heating and melting is performed, mixing with high dispersion becomes possible, and
The capacity at the cycle was about 400 mAh / g in the comparative example, whereas it was 600 mAh / g in Example 2, and the cycle characteristics could be greatly improved. From the above results, the electron conductivity in the electrode was improved and high charge / discharge characteristics were obtained by passing through the process of heating sulfur and the process of dissolving sulfur. In Comparative Examples 1 and 2, since the capacity was small and the preferable characteristics were not obtained, the average particle size of the positive electrode mixture was 5 to 10
It is preferably in the range of 0 μm. Furthermore, when the particle size distribution was measured, the maximum peak was retained near 60 μm, so the range of 50 to 70 μm is still preferable.

Example 3 The sample prepared in Example 3 and the sample prepared in Comparative Example were used as positive electrode plates,
A coin-type battery using a lithium-containing composite nitride as a negative electrode active material was prepared and the characteristics were evaluated. The electrolyte, the configuration and manufacturing method of the coin-type battery, the experimental conditions and the like were the same as in the case of Example 1.

A negative electrode containing a lithium-containing composite nitride as an active material
A method of making a pole will be shown. The molar ratio of Li / Co is 2.6 / 0.
Place the lithium cobalt alloy of No. 4 in a copper container and nitrogen
Hold at 800 ° C for 12 hours in the atmosphere to react with nitrogen.
It was After the reaction, the obtained black gray compound was crushed and
Mucobalt composite nitride powder was obtained. For synthetic samples,
Powder X-ray diffraction measurement was performed using CuKα rays. That conclusion
As a result, lithium nitride (Li ₃N) based on hexagonal crystal
A folding pattern appears, and Co dissolves in lithium nitride.
It was confirmed that it was a single phase of the state. Also synthetic
The lithium-containing composite nitride composition is Li_2.6Co_0.4At N
there were. Lithium-containing composite nitride produced in this way
Powder, carbon powder, and poly 4-fluoride as a binder
Tylene powder is mixed and kneaded at a weight ratio of 100: 25: 5.
It was After thoroughly kneading, roll this mixture on a sheet
Then, punch it out on a disk with a diameter of 13.0 mm to make an electrode plate.
It was At that time, the weight of the electrode plate was set to 25 mg.

A coin-type battery was prepared with the positive electrode plate using the sample prepared in Example 2 as the positive electrode active material and the lithium-containing composite nitride prepared by the above method as the negative electrode active material together with the electrolytic solution.

Example 4 The sample prepared in Example 2 and the sample prepared in Comparative Example were used as positive electrode plates,
A coin-type battery using a metal oxide as a negative electrode active material was prepared and the characteristics were evaluated. The electrolyte, the configuration and manufacturing method of the coin-type battery, the experimental conditions and the like were the same as in the case of Example 1. A method for producing a SiO negative electrode used as a metal oxide is shown. The positive electrode was prepared in the same manner as in Example 1.

As the negative electrode active material, SiO was used by pulverizing a commercially available reagent into powder. 250 ° C in vacuum, 5
It was used after being dried for an hour. And powder Si
O and Li _2.6 Co _0.4 N powder produced in the same manner as in Example 3 were mixed at a weight ratio of 1: 1. Then, to 100 parts by weight of this mixed active material powder, 25 parts by weight of graphite powder as a conductive agent and 5 parts by weight of Teflon (registered trademark) resin powder as a binder were added, sufficiently kneaded, and then rolled with a roller. Processed into a film. Since the manufactured negative electrode does not contain lithium, it is necessary to perform a chemical conversion treatment to insert lithium. In this example, an electrochemical lithium insertion treatment was performed on the negative electrode active material. This insertion treatment was performed by constructing an electrochemical cell using metallic lithium as a counter electrode, performing constant current electrolysis at a current value of 0.5 mA per unit area, and oxidizing it to an upper limit voltage of 1.5V. After that, the electrode plate subjected to this treatment was taken out and used as a negative electrode.

Example 5 The sample prepared in Example 2 and the sample prepared in Comparative Example were used as positive electrode plates,
A coin-type battery using the alloy negative electrode as a negative electrode active material was produced and the characteristics were evaluated. The electrolyte, the configuration and manufacturing method of the coin-type battery, the experimental conditions and the like were the same as in the case of Example 1. The method for producing the alloy negative electrode will be described below. Example of negative electrode
In the same manner as in 3, Fe ₂ Sn powder, SiO powder, Li _2.6
Co _0.4 N powder was prepared. And Fe ₂ Sn: Si
O: Li _2.6 Co _0.4 N was mixed in a weight ratio of 1: 1: 2. Then, to 100 parts by weight of this mixed active material powder, 25 parts by weight of graphite powder as a conductive agent and 5 parts by weight of Teflon resin powder as a binder were added, sufficiently kneaded, and then rolled with a roller to form a film. processed. Since the manufactured negative electrode does not contain lithium, it is necessary to perform a chemical conversion treatment to insert lithium. In this example, an electrochemical lithium insertion treatment was performed on the negative electrode active material in the same manner as in Example 4.

(Comparative Example 3) A positive electrode plate using the sample prepared in Example 2 as a positive electrode active material and lithium metal as a negative electrode active material were used to prepare a coin-type battery together with an electrolytic solution. The charge and discharge characteristics of the coin type batteries prepared in Examples 3, 4 and 5 and Comparative Example 3 were evaluated. The charge / discharge test results at this time are shown in FIG. Only when lithium metal was used for the negative electrode, capacity deterioration was observed after 50 cycles. When the metal oxide negative electrode and the alloy negative electrode were used, the capacity deterioration was not observed even after 60 cycles, and particularly when the lithium-containing composite nitride negative electrode was used, the capacity deterioration was not observed even after exceeding 100 cycles. This is because when lithium metal is used as the negative electrode active material, as the charge and discharge cycle is repeated,
It is considered that a lithium compound such as lithium carbonate is generated and deposited on the lithium metal. It is considered that this deteriorated the lithium metal negative electrode and deteriorated the discharge capacity. on the other hand,
It is considered that when the lithium-containing composite nitride negative electrode was used, the deterioration of the discharge capacity was not observed even after 100 cycles because the deterioration of the negative electrode itself due to the cycle was very small. When a metal oxide negative electrode or an alloy negative electrode is used,
It is considered that deterioration with cycling is less than that of lithium metal.

The theoretical capacity of a lithium cobalt oxide-carbon negative electrode battery, which is currently widely used as a positive electrode material of a lithium secondary battery, is 145 mAh, but a sulfur positive electrode-lithium-containing composite nitride negative electrode battery has a high capacity of about 600 mAh. Obtainable. In the case of the sulfur positive electrode-metal lithium battery, a battery having a higher capacity than the sulfur positive electrode-lithium-containing composite nitride negative electrode battery can be expected, but there is a problem in cycle characteristics.

It should be noted that when manufacturing in this embodiment, N-
Methylpyrrolidone was used, but this is a commercially available reagent as it is, or a zeolite adsorbent allows water content of 20 ppm.
Those reduced below can be used. In addition, in addition, pyrrolidone, N-ethyl-2-pyrrolidone, N-
Butyl-2-pyrrolidone or the like can also be used.

Further, although aluminum foil is used as the electrode current collector in this embodiment, metal foil such as copper or stainless steel, conductive polymer film such as polyaniline or polypyrrole, or conductive polymer is used. It is also possible to use a metal foil or carbon sheet coated or covered with a membrane film.

Further, in the negative electrode active material of this embodiment,
A lithium-containing composite nitride using Co was prepared, but other transition metals such as Ti, V, Cr, Mn, and F were prepared.
You may use e, Ni, Cu, etc. Also C
Two kinds of transition elements selected from these groups containing o may be used.

[0048]

INDUSTRIAL APPLICABILITY The composite electrode of the present invention provides a battery having higher cycle characteristics and higher energy density than the conventional lithium battery.

[Brief description of drawings]

FIG. 1 is a diagram including a vertical cross section of a coin-type test cell that is a first embodiment of a lithium battery of the present invention.

FIG. 2 is a particle structure diagram of the positive electrode material of the present invention.

FIG. 3 is a diagram showing the results of charge / discharge tests of the batteries manufactured in Examples 3, 4 and 5 of the present invention.

[Explanation of symbols]

11 Positive electrode plate 12 cases 13 Current collector 14 gel electrolyte 15 separator 21 Sulfur particles 22 Conductive agent 23 Solid electrolyte

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Nitta             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5H029 AJ02 AK05 AL01 AM03 AM07                       AM12 BJ03 BJ13 CJ02 DJ08                       DJ09 DJ16 EJ04 EJ13 HJ01                       HJ02 HJ05                 5H050 AA02 BA17 CA11 CB01 DA02                       DA10 DA13 EA08 EA15 EA23                       EA26 FA17 FA18 GA02 HA01                       HA02 HA05

Claims (6)

[Claims] 1. The general formula (Li _x S) _n (0 <x ≦ 1.5,
n is an integer of 1 or more), and a positive electrode having a compound represented by the following:
General formula Li _3-y M _y N (0.2 ≦ y ≦ 0.8, M is Ti,
A compound represented by at least one element selected from V, Cr, Mn, Fe, Co, Ni, and Cu) or
A lithium battery comprising a negative electrode containing at least one of a solid solution of Sn and Si, an intermetallic compound of Sn or Si, or an oxide of Sn or Si, and an electrolytic solution. 2. When the positive electrode mixture weight is 100% by weight,
The compound represented by the general formula (Li _x S) _n (0 <x ≦ 1.5, n is an integer of 1 or more) is 60 to 98% by weight, and the solid electrolyte is 20
˜1 wt%, and the conductor is 20 to 1 wt%, and has a solid electrolyte on the particle surface of the compound represented by (Li _x S) _n and a conductor that controls the electron conductivity in the positive electrode. The lithium battery according to claim 1, wherein: 3. The solid electrolyte is Li ₂ S—SiS _{(2 + a)} (where a is
At least one selected from Li ₃ PO ₄ , LiI, and Li ₄ SiO ₄ ), L
The lithium battery according to claim 2, comprising at least one selected from i ₂ SP ₂ O ₅ , Li ₂ SB ₂ S ₅ , and Li ₂ SP ₂ S ₅ -GeS ₂ . 4. The conductor controlling the electron conductivity in the positive electrode is at least selected from a conductive carbon material, polyaniline, polypyrrole, polythiophene and polyacetylene.
The lithium battery according to claim 2, which has one kind. 5. The general formula (Li _x S) _n (0 <x ≦ 1.5,
The average particle shape of the compound represented by
The lithium battery according to claim 2, which has a particle shape of 100 μm. 6. The general formula (Li _x S) _n (0 <x ≦ 1.5,
The positive electrode having a compound represented by the formula (n is an integer of 1 or more) is
3. The method for producing a lithium battery according to claim 1, further comprising a heating process, a dissolution process, and a process of mixing with a solid electrolyte and a conductor controlling electronic conductivity in the positive electrode.