JP2006024415A - Cathode material and battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cathode material capable of improving battery characteristics such as cycle characteristics, and a battery using the same. <P>SOLUTION: The cathode 12 contains metal sulfide MI<SB>x</SB>MII<SB>1-x</SB>S<SB>y</SB>as a cathode active material. MI is at least one out of a group consisting of Ni, Co, Fe, Mn, V, Ti, Mo and W; MII is at least one out of a group consisting Fe, Cu, Ni, Co, Mn, V, Ti, Mg, and Zn; MI is an element different from MII; and (x) and (y) satisfy 0<x<1, and 0.5<y<2.5. Stability of a structure is improved by containing MI and MII. The metal sulfide is preferred to constitute a complex material together with carbon material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a positive electrode material containing a metal sulfide and a battery using the same.

  In recent years, the power consumption of devices has increased with the increase in functionality and performance of portable devices, and a further increase in capacity has been demanded for batteries serving as power sources. Among these, from the viewpoint of economy and reduction in size and weight of equipment, there is a great demand for secondary batteries. In addition, with the reduction in voltage of devices, research and development has been conducted on secondary batteries having a battery voltage of around 1.5 V, and some of them have been put into practical use.

  Conventionally, nickel-cadmium batteries or nickel metal hydride batteries are used as secondary batteries of about 1.5 V, but it is difficult to further increase the capacity of these secondary batteries. Accordingly, lithium secondary batteries have been studied as those capable of obtaining high output and high energy density.

As the positive electrode material of the lithium secondary battery, metal oxide, metal sulfide, metal selenide, polymer, or the like is used. For example, titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), niobium selenide ( NbSe ₂ ), lithium (Li) -free compounds such as vanadium pentoxide (V ₂ O ₅ ), or lithium-containing oxides such as LiCoO ₂ , LiNiO ₂ , or LiMn ₂ O ₄ are known. Yes. Some of them have a voltage of about 1.5V with respect to lithium.

For example, Patent Document 1 describes a lithium secondary battery using iron sulfide (FeS) as a positive electrode, and Non-Patent Document 1 describes a lithium secondary battery using nickel sulfide (NiS) as a positive electrode. Yes.
Japanese Patent No. 3447187 Jay. Alloys and Compounds, 2003, No. 351, p. 273

  However, these metal sulfides have a problem that the crystal structure changes with charge / discharge, and the capacity decreases. In addition, there is a problem that an inactive product is produced by reacting with the electrolyte, and charge / discharge efficiency is lowered. Therefore, battery characteristics such as cycle characteristics are not sufficient.

  The present invention has been made in view of such problems, and an object thereof is to provide a positive electrode material capable of improving battery characteristics such as cycle characteristics and a battery using the same.

The first positive electrode material according to the present invention contains a metal sulfide represented by Chemical Formula 1.
(Chemical formula 1)
MI _x MII _1-x S _y
(In the formula, MI represents a first metal element, and nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), vanadium (V), titanium (Ti), molybdenum (Mo) and tungsten ( W) at least one member selected from the group consisting of W), MII represents a second metal element, and includes iron, copper (Cu), nickel, cobalt, manganese, vanadium, titanium, magnesium (Mg), and zinc (Zn). It is at least one member of the group and is an element different from the first metal element, where x and y are values in the range of 0 <x <1, 0.5 <y <2.5, respectively. .)

The second positive electrode material according to the present invention includes a composite material of a metal sulfide represented by Chemical Formula 2 and a carbon material.
(Chemical formula 2)
MI _x MII _1-x S _y
(In the formula, MI represents the first metal element and is at least one member selected from the group consisting of nickel, cobalt, iron, manganese, vanadium, titanium, molybdenum and tungsten. MII represents the second metal element, and iron. , Copper, nickel, cobalt, manganese, vanadium, titanium, magnesium, and zinc, and is different from the first metal element, where x and y are each 0 <x <1 , 0.5 <y <2.5.)

A first battery according to the present invention includes an electrolyte together with a positive electrode and a negative electrode, and the positive electrode includes a metal sulfide represented by Chemical Formula 3.
(Chemical formula 3)
MI _x MII _1-x S _y
(In the formula, MI represents the first metal element and is at least one member selected from the group consisting of nickel, cobalt, iron, manganese, vanadium, titanium, molybdenum and tungsten. MII represents the second metal element, and iron. , Copper, nickel, cobalt, manganese, vanadium, titanium, magnesium, and zinc, and is different from the first metal element, where x and y are each 0 <x <1 , 0.5 <y <2.5.)

A second battery according to the present invention includes an electrolyte together with a positive electrode and a negative electrode, and the positive electrode includes a composite material of a metal sulfide represented by Chemical Formula 4 and a carbon material.
(Chemical formula 4)
MI _x MII _1-x S _y
(In the formula, MI represents the first metal element and is at least one member selected from the group consisting of nickel, cobalt, iron, manganese, vanadium, titanium, molybdenum and tungsten. MII represents the second metal element, and iron. , Copper, nickel, cobalt, manganese, vanadium, titanium, magnesium, and zinc, and is different from the first metal element, where x and y are each 0 <x <1 , 0.5 <y <2.5.)

  According to the first positive electrode material of the present invention, since the metal sulfide represented by Chemical Formula 1 is included, for example, when used in a battery, it is possible to suppress structural changes that occur during charging and discharging. And reversibility of the charge / discharge reaction can be improved. Therefore, battery characteristics such as cycle characteristics can be improved.

  According to the second positive electrode material of the present invention, since the composite material of the metal sulfide represented by Chemical Formula 2 and the carbon material is included, for example, when used for a battery, it is generated at the time of charge / discharge. The structure change can be suppressed and the side reaction with the electrolyte can be suppressed. Therefore, the reversibility of the charge / discharge reaction can be further improved, and battery characteristics such as cycle characteristics can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The positive electrode material according to one embodiment of the present invention contains a metal sulfide represented by Chemical Formula 5.
(Chemical formula 5)
MI _x MII _1-x S _y
(In the formula, MI represents the first metal element and is at least one member selected from the group consisting of nickel, cobalt, iron, manganese, vanadium, titanium, molybdenum and tungsten. MII represents the second metal element, and iron. , Copper, nickel, cobalt, manganese, vanadium, titanium, magnesium, and zinc, and is different from the first metal element, where x and y are each 0 <x <1 , 0.5 <y <2.5.)

  This metal sulfide contains two or more metal elements, thereby improving the structural stability. Further, as shown in Chemical formula 5, the sulfur (S) composition y provides a stable structure within the range of 0.5 to 2.5.

Examples of such metal sulfides, for _{example, Ni x Fe 1-x S} y, Ni x Cu 1-x S y, Ni x Co 1-x S y, Ni x (Fe, Cu) 1- _{x S y, Co x Fe 1} -x S y, Co x Cu 1-x S y, Co x Ni 1-x S y and _{Co x (Fe, Cu) 1} -x S y and the like. This metal sulfide may be used alone or in combination of two or more.

  In addition, it is preferable that this metal sulfide comprises the composite material with the carbon material. For example, such a composite material preferably has a structure in which at least a part of the particles made of the metal sulfide is covered with a carbon material. Thereby, the irreversible reaction of the metal sulfide can be suppressed. Examples of the carbon material include graphite and carbon blacks.

  This positive electrode material can be manufactured, for example, by a mechanochemical method. For example, the first metal element MI, the second metal element MII, and sulfur raw material powder are mixed according to the target composition, and this mixture is subjected to a mechanochemical reaction using a ball mill to synthesize the metal sulfide described above. . When the metal sulfide is used as a composite material, for example, the metal sulfide powder and the carbon material powder are mixed, and mixed and pulverized by a ball mill.

  Such a positive electrode material is used, for example, in the following secondary battery.

  FIG. 1 shows a cross-sectional structure of a secondary battery using the positive electrode material according to the present embodiment. This secondary battery is a so-called coin-type battery. The disc-shaped positive electrode 12 accommodated in the outer can 11 and the disc-shaped negative electrode 14 accommodated in the outer cup 13 form the separator 15. Are stacked. The separator 15 is impregnated with an electrolytic solution that is a liquid electrolyte, and the outer peripheral portions of the outer can 11 and the outer cup 13 are sealed by caulking through a gasket 16. The outer can 11 and the outer cup 13 are made of, for example, a metal such as stainless steel or aluminum (Al).

  The positive electrode 12 includes, for example, a positive electrode current collector 12A and a positive electrode active material layer 12B provided on the positive electrode current collector 12A. The positive electrode current collector 12A is made of, for example, a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil. The positive electrode active material layer 12B contains, for example, the positive electrode material according to the present embodiment as a positive electrode active material, and is configured with a conductive agent such as carbon black or graphite and a binder such as polyvinylidene fluoride as necessary. ing. Moreover, the other positive electrode active material may further be included.

  The negative electrode 14 includes, for example, a negative electrode current collector 14A and a negative electrode active material layer 14B provided on the negative electrode current collector 14A. The negative electrode current collector 14A is made of, for example, a metal foil such as a copper foil, a nickel foil, or a stainless steel foil.

The negative electrode active material layer 14B includes, for example, one or more of a negative electrode material capable of inserting and extracting lithium, lithium metal, and a lithium alloy as a negative electrode active material. And a binder such as polyvinylidene fluoride. Examples of the anode material capable of inserting and extracting lithium include carbon materials, metal compounds, tin, tin alloys, silicon, silicon alloys, and conductive polymers, and any one or more of these are mixed. Used. Examples of the carbon material include graphite, non-graphitizable carbon, and graphitizable carbon, and examples of the metal compound include lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) having a spinel structure, tungsten oxide (WO ₂ ), Oxides such as niobium oxide (Nb ₂ O ₅ ) or tin oxide (SnO), and examples of the conductive polymer include polyacetylene and polypyrrole. Among them, a carbon material is preferable because a change in crystal structure that occurs during charge and discharge is very small and good cycle characteristics can be obtained.

  The separator 15 separates the positive electrode 12 and the negative electrode 14 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 15 is made of, for example, a porous film made of a synthetic resin made of polytetrafluoroethylene, polypropylene, polyethylene, or the like, or a porous film made of an inorganic material such as a ceramic nonwoven fabric. The porous film may be laminated.

The electrolytic solution is obtained by dissolving an electrolyte salt in a solvent, and exhibits ion conductivity when the electrolyte salt is ionized. Examples of the electrolyte salt include lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium boron tetrafluoride (LiBF ₄ ), and trifluoromethanesulfonic acid. Examples thereof include lithium salts such as lithium (LiCF ₃ SO ₃ ) or bis (trifluoromethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ). Any one electrolyte salt may be used alone, or two or more electrolyte salts may be mixed and used.

  Examples of the solvent include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, sulfolane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 2-methyltetrahydrofuran, 1,3-dioxolane, 3- Nonaqueous solvents such as methyl-1,3-dioxolane, methyl propionate, methyl butyrate, dimethyl carbonate, diethyl carbonate or dipropyl carbonate are preferred. Any one of the solvents may be used alone, or two or more may be mixed and used.

  This secondary battery can be manufactured, for example, as follows.

  First, for example, after mixing the positive electrode material described above with a conductive agent and a binder as necessary to prepare a positive electrode mixture, and dispersing it in a solvent such as N-methyl-2-pyrrolidone to make a paste, The positive electrode current collector 12 </ b> A is applied to the solvent, and the solvent is dried.

  Next, for example, a negative electrode active material and, if necessary, a binder are mixed to prepare a negative electrode mixture, which is dispersed in a solvent such as N-methyl-2-pyrrolidone and pasted into a negative electrode current collector. It is applied to 14A, the solvent is dried, and compression molding is performed by a roll press or the like to form the negative electrode active material layer 14B. Further, for example, the negative electrode active material layer 14 </ b> B is formed on the negative electrode current collector 14 </ b> A by vapor deposition or plating to form the negative electrode 14.

  Subsequently, the negative electrode 14 and the separator 15 are placed in this order at the center of the outer cup 13, the electrolyte is poured from above the separator 15, and the outer can 11 containing the positive electrode 12 is covered and caulked through the gasket 16. Thereby, the secondary battery shown in FIG. 1 is formed.

  In the secondary battery, when charged, for example, lithium ions are released from the positive electrode active material layer 12B and are occluded in the negative electrode 14 through the electrolytic solution or deposited as lithium metal. When the discharge is performed, for example, lithium ions are released from the negative electrode 14 or lithium metal is eluted as lithium ions and inserted into the positive electrode active material layer 12B through the electrolytic solution. At that time, since the positive electrode active material layer 12B contains the metal sulfide described above, the structural change accompanying charge / discharge is small, and the deterioration of the capacity is suppressed. In addition, if the metal sulfide is a composite material with a carbon material, side reaction between the metal sulfide and the electrolytic solution is suppressed, and capacity deterioration is further suppressed.

  As described above, according to the present embodiment, since the metal sulfide represented by Chemical Formula 5 is included, it is possible to suppress structural changes that occur during charge and discharge, and to improve the reversibility of the charge and discharge reaction. Can be made. Therefore, battery characteristics such as cycle characteristics can be improved.

  In particular, if this metal sulfide is made into a composite material with a carbon material, a side reaction between the metal sulfide and the electrolytic solution can be suppressed. Therefore, the reversibility of the charge / discharge reaction can be further improved.

  Further, specific embodiments of the present invention will be described in detail.

(Examples 1-1 to 1-4)
First, nickel powder, iron powder, copper powder, cobalt powder, and sulfur powder were prepared as raw materials and mixed so as to have the composition shown in Table 1. That is, in Example 1-1, the molar ratio of nickel, iron, copper, and sulfur was set to 1/3: 1/3: 1/3: 1. In Example 1-2, nickel, iron, and sulfur In Example 1-3, the molar ratio of nickel, iron, copper, and sulfur was 0.8: 0.1: 0.1: 1. In Example 1-4, the molar ratio of cobalt, iron, and sulfur was set to 0.8: 0.2: 1. Among these, in Examples 1-1 to 1-3, the first metal element MI is nickel and the second metal element MII is iron, or iron and copper. In Example 1-4, the first metal element MI is cobalt, The two metal element MII is iron.

  Next, this mixture was sealed in a sealed container together with hard steel balls in an argon atmosphere, and a mechanochemical reaction was performed using a ball mill to synthesize a metal sulfide. The reaction time was 10 hours.

  X-ray diffraction patterns of the obtained metal sulfides of Examples 1-1 to 1-4 were measured. A rotating counter cathode type Rigaku RINT2500 was used for the X-ray diffractometer. This X-ray diffractometer is equipped with a vertical standard radius of 185 mm as a goniometer, and without using a filter such as a Kβ filter, the X-ray diffractometer is made monochromatic by combining a wave height analyzer and a counter monochromator. The specific X-ray is detected by a scintillation counter. The measurement uses CuKα (40 kV, 100 mA) as specific X-rays, the incident angle DS with respect to the sample surface and the angle RS formed by the diffraction lines with respect to the sample surface are each 1 °, and the width SS of the incident slit is 0.15 mm. (Scanning range 2θ = 10 ° to 80 °, scanning speed 4 ° / min).

  2 and 3 representatively show the X-ray diffraction patterns obtained for Example 1-1 and Example 1-2.

  Subsequently, using the obtained metal sulfides of Examples 1-1 to 1-4, a coin-type battery as shown in FIG. 1 was prepared, a charge / discharge test was performed, and the characteristics of the positive electrode material were evaluated. went.

  At that time, the positive electrode 12 was produced as follows. First, the synthesized metal sulfide was dried and weighed 30 mg as a positive electrode material, mixed with graphite as a conductive agent and polyvinylidene fluoride as a binder, with N-methyl-2-pyrrolidone as a solvent, and pasted. The positive electrode mixture was obtained. The ratio of metal sulfide to graphite was set to a mass ratio of metal sulfide: graphite = 98: 2, and polyvinylidene fluoride was set to a ratio of 2 parts by mass with respect to 98 parts by mass of the mixture. Next, this positive electrode mixture was applied to a positive electrode current collector 12A made of an aluminum foil, and dried in a dry argon stream at 100 ° C. for 1 hour to obtain a positive electrode 12.

A lithium metal plate punched into a disc shape was used for the negative electrode 14, and 1.15 mol of LiPF ₆ was used as a lithium salt in a solvent in which 1,3-dioxolane and dimethoxyethane were mixed at a volume ratio of 2: 1 as the electrolyte. A solution dissolved at a concentration of / l was used. The size of the battery was 20 mm in diameter and 1.6 mm in height.

The charge / discharge test was performed at 23 ° C. as follows. First, 1.0 mA / battery voltage at a constant current of cm ² performs constant current discharge until a 0.8 V, then constant current until the battery voltage at a constant current of 1.0 mA / cm ² reaches 3.0 After charging, constant voltage charging was performed at a constant voltage of 3.0 V until the current became 0.1 mA / cm ² or less.

  FIG. 4 shows the charge / discharge curve of Example 1-1, FIG. 5 shows the charge / discharge curve of Example 1-2 as a representative, and Table 1 shows the first cycle of Examples 1-1 to 1-4. The charge capacity, the discharge capacity, the discharge / charge efficiency, the charge / discharge efficiency of the second cycle, and the capacity maintenance rate for the first cycle of the 30th cycle are shown. The charge / discharge efficiency in the first cycle is obtained by (charge capacity in the first cycle / discharge capacity in the first cycle) × 100, and the charge / discharge efficiency in the second cycle is (discharge capacity in the second cycle / 2 cycles). The charge capacity of the eye) × 100, and the capacity retention rate at the 30th cycle was obtained by (discharge capacity at the 30th cycle / discharge capacity at the first cycle) × 100.

  As Comparative Example 1-1 with respect to Examples 1-1 to 1-4, Examples 1-1 to 1-4 were mixed except that nickel powder and sulfur powder were mixed so that the molar ratio was 1: 1. Similarly, metal sulfide NiS was synthesized. Comparative Example 1-1 contains only one type of metal element. For the metal sulfide of Comparative Example 1-1, the X-ray diffraction pattern was measured in the same manner as in Examples 1-1 to 1-4. FIG. 6 shows the X-ray diffraction pattern. From FIG. 6, it was confirmed that the obtained metal sulfide of Comparative Example 1-1 was NiS.

  Moreover, using the metal sulfide of Comparative Example 1-1, coin-type batteries were produced in the same manner as in Examples 1-1 to 1-4, and the characteristics were evaluated in the same manner. FIG. 7 shows the charge / discharge curve, and Table 1 shows the charge capacity, discharge capacity and discharge / charge efficiency in the first cycle, charge / discharge efficiency in the second cycle, and capacity maintenance rate in the 30th cycle.

  As can be seen from a comparison of FIGS. 4, 5, and 7, in Comparative Example 1-1, a short flat portion is observed at the end of charging, whereas in Examples 1-1 and 1-2, a slow discharge curve is obtained. Such a flat portion was not observed even at the end of charging. This flat portion suggests that a phase separation reaction is occurring during charging, and it seems that the phase separation reaction is suppressed according to this example. In addition, although the charging / discharging curve was shown only about Example 1-1, 1-2, the same result was obtained also about Example 1-3, 1-4.

  Further, as can be seen from Table 1, according to Examples 1-1 to 1-4, the charge / discharge efficiency in the first cycle, the charge / discharge efficiency in the second cycle, and the 30th cycle are greater than those in Comparative Example 1-1. It was possible to improve both of the capacity maintenance ratios.

  That is, if a metal sulfide containing the first metal element MI and the second metal element MII is used, structural changes that occur during charging and discharging can be suppressed, and cycle characteristics can be improved. I understood.

(Examples 2-1 to 2-11)
After synthesizing a metal sulfide having the composition shown in Table 2 in the same manner as in Examples 1-1 to 1-4, 98 parts by mass of the obtained metal sulfide and 2 parts by mass of graphite were mixed, and a ball mill was prepared. The composite material of metal sulfide and graphite was formed by mixing and grinding for 1 hour.

In addition, the metal sulfide of Example 2-1 is Ni _1/3 Fe _1/3 Cu _1/3 S, the first metal MI is nickel, and the second metal element MII is iron and copper. The metal sulfide of Example 2-2 is Ni _0.9 Fe _0.1 S, the metal sulfide of Example 2-3 is Ni _0.5 Fe _0.5 S, the first metal MI is nickel, and the second metal element MII is iron. It is. The metal sulfide of Example 2-4 is Ni _0.9 Cu _0.1 S, the first metal MI is nickel, and the second metal element MII is copper. The metal sulfide of Example 2-5 is Ni _0.9 Co _0.1 S, the metal sulfide of Example 2-6 is Ni _0.5 Co _0.5 S, the first metal MI is nickel, and the second metal element MII is cobalt. It is. The metal sulfide of Example 2-7 is Ni _0.8 Fe _0.1 Cu _0.1 S, the first metal MI is nickel, and the second metal element MII is iron and copper. The metal sulfide of Example 2-8 is Co _0.8 Fe _0.2 S, the first metal MI is cobalt, and the second metal element MII is iron. The metal sulfide of Example 2-9 is Co _0.9 Cu _0.1 S, the first metal MI is cobalt, and the second metal element MII is copper. The metal sulfide of Example 2-10 is Co _0.9 Ni _0.1 S, the first metal MI is cobalt, and the second metal element MII is nickel. The metal sulfide of Example 2-11 is Co _0.7 Fe _0.2 Cu _0.1 S, the first metal MI is cobalt, and the second metal element MII is iron and copper.

  About the obtained composite material of Examples 2-1 to 2-11, it carried out similarly to Examples 1-1 to 1-4, and measured the X-ray-diffraction pattern. FIG. 8 shows the result of Example 2-1, FIG. 9 shows the result of Example 2-2, and FIG. 10 shows the result of Example 2-7 as a representative. As a result, in any of Examples 2-1 to 2-11, a strong intense sharp peak indicating graphite was observed in the vicinity of 2θ = 26 °, and a peak indicating the composition of each metal sulfide was also observed. It was.

  Subsequently, using the obtained composite materials of Examples 2-1 to 2-11, batteries were produced in the same manner as in Examples 1-1 to 1-4, and charge / discharge tests were similarly conducted. In preparing the positive electrode 12, 98 parts by mass of the composite material and 2 parts by mass of polyvinylidene fluoride were mixed to obtain a paste-like positive electrode mixture.

  FIG. 11 shows the discharge curve of Example 2-2 as a representative, and Table 2 shows the charge capacity, discharge capacity and discharge / charge efficiency in the first cycle of Examples 2-1 to 2-11, and the charge in the second cycle. The discharge efficiency and the capacity retention rate at the 30th cycle are shown. Table 2 also shows the results of Examples 1-1 to 1-4.

  In addition, although the discharge curve was shown only about Example 2-2, the same result was obtained also about Examples 2-1 and 2-3 to 2-11.

  As Comparative Examples 2-1 and 2-2 for Examples 2-1 to 2-11, Comparative Example 2-1 except that NiS powder was used as a metal sulfide, and Comparative Example 2-2 was a metal sulfide. A composite material was produced in the same manner as in Examples 2-1 to 2-11 except that FeS powder was used as the product. For Comparative Examples 2-1 and 2-2, secondary batteries were produced in the same manner as in Examples 2-1 to 2-11, and a charge / discharge test was performed. The obtained results are shown in Table 2.

  As can be seen from Table 2, according to Examples 2-1 to 2-11, the charge / discharge efficiency in the first cycle, the charge / discharge efficiency in the second cycle, and 30, compared with Comparative Examples 2-1 and 2-2. It was possible to improve both the capacity retention ratios at the cycle. Further, as can be seen from a comparison between Examples 2-1 to 2-11 and Examples 1-1 to 1-4, Examples 2-1 to 2- in which a composite material of a metal sulfide and a carbon material is used. 11 was improved in all cases.

  That is, if a composite material of a metal sulfide containing the first metal element MI and the second metal element MII and a carbon material is used, the reversibility of the charge / discharge reaction can be further improved, and the cycle characteristics can be improved. It was found that can be further improved.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the case where an electrolytic solution that is a liquid electrolyte is used has been described, but another electrolyte may be used. Other electrolytes include, for example, a gel electrolyte in which an electrolytic solution is held in a polymer compound, a polymer electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, ion conductive ceramics, and ion conductive glass Or the inorganic solid electrolyte which consists of an ionic crystal etc., molten salt electrolyte, or what mixed these is mentioned.

  In the above-described embodiments and examples, the coin-type secondary battery has been specifically described, but the present invention has other shapes such as a cylindrical shape having another structure, a button shape, or a square shape. The present invention can be similarly applied to a secondary battery or a secondary battery having another structure such as a winding structure. Furthermore, the present invention can be similarly applied to other batteries such as a primary battery.

  Furthermore, although the case where the positive electrode material of the present invention was synthesized by mechanochemical was described in the above embodiment and examples, it may be synthesized by other manufacturing methods.

It is sectional drawing showing the structure of the secondary battery using the positive electrode material which concerns on one embodiment of this invention. It is a characteristic view showing the X-ray-diffraction pattern of the metal sulfide Ni1 _/ 3Fe1 _/ 3Cu1 _/ 3S which concerns on Example 1-1 of this invention. It is a plot showing the X-ray diffraction pattern of the metal sulfide Ni _0.9 Fe _0.1 S according to the embodiment 1-2 of the present invention. It is a characteristic view showing the charging / discharging curve which concerns on Example 1-1 of this invention. It is a characteristic view showing the charging / discharging curve which concerns on Example 1-2 of this invention. It is a characteristic view showing the X-ray-diffraction pattern of the metal sulfide NiS concerning the comparative example 1-1. It is a characteristic view showing the charging / discharging curve concerning the comparative example 1-1. It is a characteristic view showing the X-ray-diffraction pattern of composite material Ni1 _/ 3Fe1 _/ 3Cu1 _/ 3SC which _concerns on Example 2-1 of this invention. Is a plot showing the X-ray diffraction pattern of the composite Ni _0.9 Fe _0.1 S-C according to Example 2-2 of the present invention. Is a plot showing the X-ray diffraction pattern of the composite material according to Example _{2-7 Ni 0.8 Fe 0.1 Cu 0.1 S} -C of the present invention. It is a characteristic view showing the discharge curve concerning Example 2-2 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Outer can, 12 ... Positive electrode, 12A ... Positive electrode collector, 12B ... Positive electrode active material layer, 13 ... Outer cup, 14 ... Negative electrode, 14A ... Negative electrode collector, 14B ... Negative electrode active material layer, 15 ... Separator, 16 ... gasket.

Claims (6)

A positive electrode material comprising a metal sulfide represented by Chemical Formula 1.
(Chemical formula 1)
MI _x MII _1-x S _y
(In the formula, MI represents a first metal element, and nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), vanadium (V), titanium (Ti), molybdenum (Mo) and tungsten ( W) at least one member selected from the group consisting of W), MII represents a second metal element, and includes iron, copper (Cu), nickel, cobalt, manganese, vanadium, titanium, magnesium (Mg), and zinc (Zn). It is at least one member of the group and is an element different from the first metal element, where x and y are values in the range of 0 <x <1, 0.5 <y <2.5, respectively. .) A positive electrode material comprising a composite material of a metal sulfide represented by Chemical Formula 2 and a carbon material.
(Chemical formula 2)
MI _x MII _1-x S _y
(In the formula, MI represents a first metal element, and nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), vanadium (V), titanium (Ti), molybdenum (Mo) and tungsten ( W) at least one member selected from the group consisting of W), MII represents a second metal element, and includes iron, copper (Cu), nickel, cobalt, manganese, vanadium, titanium, magnesium (Mg), and zinc (Zn). It is at least one member of the group and is an element different from the first metal element, where x and y are values in the range of 0 <x <1, 0.5 <y <2.5, respectively. .)   3. The positive electrode material according to claim 2, wherein the composite material is a material in which at least a part of particles made of the metal sulfide is covered with a carbon material. A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The battery, wherein the positive electrode contains a metal sulfide represented by Chemical Formula 3.
(Chemical formula 3)
MI _x MII _1-x S _y
(In the formula, MI represents a first metal element, and nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), vanadium (V), titanium (Ti), molybdenum (Mo) and tungsten ( W) at least one member selected from the group consisting of W), MII represents a second metal element, and includes iron, copper (Cu), nickel, cobalt, manganese, vanadium, titanium, magnesium (Mg), and zinc (Zn). It is at least one member of the group and is an element different from the first metal element, where x and y are values in the range of 0 <x <1, 0.5 <y <2.5, respectively. .) A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The battery, wherein the positive electrode includes a composite material of a metal sulfide represented by Chemical Formula 4 and a carbon material.
(Chemical formula 4)
MI _x MII _1-x S _y
(In the formula, MI represents a first metal element, and nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), vanadium (V), titanium (Ti), molybdenum (Mo) and tungsten ( W) at least one member selected from the group consisting of W), MII represents a second metal element, and includes iron, copper (Cu), nickel, cobalt, manganese, vanadium, titanium, magnesium (Mg), and zinc (Zn). It is at least one member of the group and is an element different from the first metal element, where x and y are values in the range of 0 <x <1, 0.5 <y <2.5, respectively. .) 6. The battery according to claim 5, wherein the composite material is one in which at least a part of particles made of the metal sulfide is covered with a carbon material.

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