JP4501181B2 - Non-aqueous electrolyte battery and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nonaqueous electrolyte battery including a negative electrode including a negative electrode active material, a positive electrode including a positive electrode active material, and a nonaqueous electrolyte, and particularly relates to a nonaqueous electrolyte battery using magnesium ions as a charge carrier. It is.
[0002]
[Prior art]
Non-aqueous electrolyte batteries can withstand heavy load discharge and can be used repeatedly by charging, so they are used in various electronic devices such as camera-integrated video tape recorders, mobile phones, and laptop computers as portable power sources. . As these electronic devices have been reduced in size and weight one after another, non-aqueous electrolyte batteries as portable power sources have been required to be further reduced in size, weight, and energy density. It is increasing.
[0003]
Among nonaqueous electrolyte secondary batteries that meet these requirements, lithium ion secondary batteries and nickel metal hydride secondary batteries are widely used because of their high energy density compared to lead batteries and nickel cadmium batteries. The market is also growing significantly. On the other hand, attempts have been made to use magnesium ions and calcium ions having a divalent charge as charge carriers for secondary batteries with the aim of further improving energy density.
[0004]
As an example of a calcium ion secondary battery, a carbon material such as graphite and coke is used as a negative electrode material, and CaCo ₂ O ₄ , Ca ₃ Co ₄ O ₉ , Ca ₂ Co ₂ O ₅ , and Ca ₃ Co ₂ O ₆ are used as a positive electrode material. Non-aqueous electrolyte secondary batteries using calcium-containing metal oxides such as CaFeO ₃ and CaFeO ₂ have already been disclosed in JP-A-6-163080. Further, in order to improve the capacity per unit weight of the calcium ion positive electrode, a non-aqueous electrolyte battery using, as a positive electrode material, calcium silicide or germanium instead of calcium oxide is disclosed in JP-A-8-321305. It is disclosed.
[0005]
Further, regarding a magnesium ion secondary battery, an electrolytic solution in which TiS ₂ , ZrS ₂ , RuO ₂ , Co ₃ O ₄ , V ₂ O ₅ or the like is used as a positive electrode and Mg (ClO ₄ ) ₂ is dissolved in acetonitrile as a nonaqueous electrolyte. A report that a battery capacity of about 170 mAh / g was obtained in the system using Made by Novak et al. Electrochem. Soc. , Vol. 140 No. 1, Jan (1993) 140. Further, an example in which MoO ₃ occluded Mg ²⁺ ions is used as the positive electrode active material is also described in M.S. E. Spahr; Power Sources 54 (1995) 346.
[0006]
As described above, these magnesium ion secondary batteries are expected as batteries having load characteristics surpassing those of lithium ion secondary batteries.
[0007]
[Problems to be solved by the invention]
However, as the positive electrode active material, a nonaqueous electrolyte battery using TiS ₂ , ZrS ₂ , RuO ₂ , Co ₃ O ₄ , V ₂ O ₅ , or the like, or MoO ₃ occluded with Mg ²⁺ ions is used. In the conventional non-aqueous electrolyte battery, since the magnesium ion path in the positive electrode active material crystal is one-dimensional, the diffusion of magnesium ions in the positive electrode active material is slowed. As a result, load characteristics, cycle characteristics, etc. Causes the problem of worsening.
[0008]
In addition to conventional TiS ₂ , ZrS ₂ , RuO ₂ , Co ₃ O ₄ , V ₂ O ₅ , MoO _{3 and the} like as the positive electrode active material, Li _x MO ₂ used as the positive electrode active material of the lithium ion secondary battery. (Here, M contains one or both of Ni and Co.) The lithium released from lithium can be used as the positive electrode of the magnesium ion battery. The positive electrode produced by this method has improved load characteristics and cycle characteristics because the magnesium ion path is two-dimensional. In this method, the step of producing a positive electrode used for a lithium ion secondary battery, and Since a process for releasing lithium ions from the produced positive electrode is required, there arises a problem that the manufacturing process becomes complicated and a problem that the cost increases.
[0009]
The present invention has been proposed in view of such conventional circumstances, and uses non-aqueous electrolyte batteries that use magnesium ions as charge carriers, facilitate the diffusion of magnesium ions, and improve load characteristics and cycle characteristics. The purpose is to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a nonaqueous electrolyte battery according to the present invention includes a negative electrode including a negative electrode active material containing magnesium metal, a magnesium alloy, or a material capable of occluding and releasing magnesium, and a general formula MgMn ₂ O ₄ . A positive electrode containing a positive electrode active material containing a magnesium-manganese composite oxide and a non-aqueous electrolyte, and the positive electrode active material is a magnesium and manganese hydroxide obtained from a mixed solution of magnesium chloride and manganese chloride Is washed until the filtrate becomes neutral and then calcined at 700 to 900 ° C. The nonaqueous electrolyte contains a compound represented by Mg (ClO ₄ ) ₂ .
The nonaqueous electrolyte battery manufacturing method according to the present invention includes a negative electrode including a negative electrode active material containing magnesium metal, a magnesium alloy or a material capable of occluding and releasing magnesium, and a magnesium represented by the general formula MgMn ₂ O _4. A method for producing a non-aqueous electrolyte battery comprising a positive electrode containing a positive electrode active material containing a manganese composite oxide and a non-aqueous electrolyte, the magnesium and manganese hydroxides obtained from a mixed solution of magnesium chloride and manganese chloride Is washed until the filtrate becomes neutral, and then fired at 700 to 900 ° C. to obtain a positive electrode active material.
[0011]
According to the nonaqueous electrolyte battery using magnesium ions as a charge carrier according to the present invention configured as described above, the lithium ion released from the positive electrode is not used as the positive electrode, but contains magnesium in advance. By using the positive electrode, the process for manufacturing the positive electrode is simplified, so that the cost can be reduced. In the above non-aqueous electrolyte battery, magnesium ions are ion-conducted two-dimensionally in the positive electrode, so that magnesium ions are efficiently diffused, and load characteristics and cycle characteristics are improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a nonaqueous electrolyte battery according to the present invention will be described in detail with reference to the drawings. A nonaqueous electrolyte battery 1 to which the present invention is applied includes a negative electrode 2, a negative electrode can 3 that houses the negative electrode 2, a positive electrode 4, and a positive electrode can that houses the positive electrode 4, as shown in FIG. 5, a separator 6 disposed between the positive electrode 4 and the negative electrode 2, and a gasket 7. The negative electrode can 3 and the positive electrode can 5 are filled with a nonaqueous electrolytic solution.
[0013]
The negative electrode 2 is made of a metal magnesium foil obtained by rolling metal magnesium serving as a negative electrode active material. In addition to the above, for example, a magnesium compound powder and a binder are mixed, and an organic solvent such as formamide or N-methylpyrrolidone is added to prepare a paste-like negative electrode mixture. Can be applied to a negative electrode current collector such as an aluminum foil and dried to be used as the negative electrode 2. A conventionally well-known binder can be used for the said binder.
[0014]
The negative electrode active material can be used without limitation as long as it is a material that can occlude and release magnesium. For example, metal magnesium alone, an alloy of metal magnesium and an alkali metal, and a conductive material in which magnesium is occluded. Polymer or layered compound (carbon material, metal oxide, etc.) can be used.
[0015]
The negative electrode can 3 accommodates the negative electrode 2 and also serves as the external negative electrode of the nonaqueous electrolyte battery 1.
[0016]
The positive electrode 4 contains a magnesium manganese composite oxide represented by the general formula MgMn ₂ O ₄ as a positive electrode active material. This magnesium manganese complex oxide can be prepared by a solution method or a solid phase method.
[0017]
In the case of the solution method, a magnesium chloride solution and a manganese chloride solution are mixed at a predetermined ratio, and further, ammonia water and hydrogen peroxide solution are added to this mixed solution and left at room temperature for about one week. Precipitate manganese hydroxide. These precipitates are filtered off and washed thoroughly until the filtrate is neutral. Thereafter, the collected precipitate is dried and fired at 700 to 900 ° C. for 3 to 5 hours. MgMn ₂ O ₄ can be obtained through the above steps.
[0018]
In the case of the solid phase method, manganese oxide and a magnesium compound are mixed at a predetermined ratio, and the product obtained by performing the heat treatment in the range of 650 ° C. to 1000 ° C. is sufficiently washed with warm water to make MgMn ₂ O ₄ can be obtained.
[0019]
The positive electrode 4 is obtained by processing into a pellet by compressing and molding a positive electrode mixture prepared by kneading the MgMn ₂ O ₄ powder obtained by the above method, a conductive agent, and a binder. It is done. In addition, the MgMn ₂ O ₄ powder, a conductive agent, and a binder are mixed, and an organic solvent such as formamide and N-methylpyrrolidone is added to prepare a paste-like positive electrode mixture. Then, this can be applied to a positive electrode current collector such as an aluminum foil and dried to be used as the positive electrode 4.
[0020]
As the conductive agent, for example, a carbonaceous material such as carbon black or graphite can be used. As the binder, for example, polyvinylidene fluoride can be used.
[0021]
The positive electrode can 5 accommodates the positive electrode 4 and serves as an external positive electrode of the nonaqueous electrolyte battery 1.
[0022]
The separator 6 separates the positive electrode 4 and the negative electrode 2, and a conventionally known material that is usually used as a separator for this type of nonaqueous electrolyte battery can be used. For the separator 6, for example, a polymer film such as polypropylene can be used. In addition, from the relationship between lithium ion conductivity and energy density, the separator needs to be as thin as possible. Specifically, the thickness of the separator is preferably 50 μm or less, for example.
[0023]
The gasket 7 is incorporated in and integrated with the negative electrode can 3. The gasket 7 is for preventing leakage of the non-aqueous electrolyte filled in the negative electrode can 3 and the positive electrode can 5.
[0024]
The nonaqueous electrolytic solution is obtained by dissolving an electrolyte in a nonaqueous solvent. Examples of the non-aqueous solvent for the non-aqueous electrolyte include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyllactone, sulfolane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 2-methyl. Tetrahydrofuran, 3-methyl-1,3-dioxolane, methyl propionate, methyl butyrate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate and the like can be used. In particular, from the viewpoint of voltage stability, it is preferable to use cyclic carbonates such as propylene carbonate and vinylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and dipropyl carbonate. Moreover, such a non-aqueous solvent may be used individually by 1 type, and 2 or more types may be mixed and used for it.
[0025]
The electrolyte of the non-aqueous electrolyte solution is not particularly limited as long as the electrolyte itself is soluble in the non-aqueous solvent and exhibits ion conductivity. For example, magnesium salts such as Mg (SO ₂ CH ₃ ) ₂ , Mg (BF ₄ ) ₂ , Mg (CF ₃ SO ₃ ) ₂ , Mg (PF ₆ ) ₂ can be used. In particular, Mg (ClO ₄ ) ₂ is preferably used.
[0026]
In the non-aqueous electrolyte battery described above, the electrolyte is not limited to being liquid, and may be a solid electrolyte or a gel electrolyte swollen with a solvent. Moreover, the components of the nonaqueous electrolyte battery such as a battery can, a separator, and a gasket and the shape of the battery are not particularly limited. The shape of the battery can be used in various shapes such as a film type, a wound type, a laminated type, a cylindrical type, and a rectangular type. Furthermore, the nonaqueous electrolyte battery described above may be a primary battery or a secondary battery.
[0027]
【Example】
Examples of the invention and comparative examples will be described in detail, but the present invention is not limited to these examples. A nonaqueous electrolyte battery 1 using magnesium ions as a charge carrier was produced as follows, and the battery characteristics were evaluated.
[0028]
<Example 1>
MgMn ₂ O ₄ used as the positive electrode active material was produced by the following solution method. First, in a mixed solution of 500 ml of a magnesium chloride solution having a concentration of 2 mol / l and 500 ml of a manganese chloride solution having a concentration of 1 mol / l, 1000 ml of 25% ammonia water was added and sufficiently stirred. A homogeneous solution was obtained. Further, 260 ml of hydrogen peroxide having a concentration of 30% was gradually added to the homogeneous solution to obtain a hydroxide precipitate. The precipitate was allowed to stand for 5 days, then filtered off, and washed with distilled water until the filtrate became neutral. Thereafter, the collected precipitate was dried in a constant temperature bath maintained at 120 ° C. for 3 hours, and then calcined at 800 ° C. for 3 hours.
[0029]
When the X-ray diffraction measurement of the sample obtained as described above was performed, the result shown in FIG. 2 was obtained. This is almost the same as the X-ray diffraction measurement chart of MgMn ₂ O ₄ shown in the card number 23-392 of the JCPDS card, so the sample produced by the above method was considered to be MgMn ₂ O ₄ . As described above, spinel-type MgMn ₂ O ₄ was obtained.
[0030]
Next, the MgMn ₂ O ₄ powder, the graphite powder, and the polyvinylidene fluoride obtained by the above-described method were weighed so that the weight ratio was 85: 10: 5. It was dispersed in N-methyl-2-pyrrolidone and kneaded to prepare a positive electrode mixture. By compressing 60 mg of this positive electrode mixture and an aluminum mesh as a positive electrode current collector, a pellet-shaped positive electrode 4 having a diameter of 15 mm was produced.
[0031]
On the other hand, for the negative electrode 2, a circular magnesium foil plate obtained by rolling metal magnesium so as to be substantially the same type as the positive electrode 4 was used.
[0032]
Next, Mg (ClO ₄ ) ₂ is dissolved at a concentration of 1 mol / l in a solvent in which 50 parts by volume of ethylene carbonate and 50 parts by volume of dimethyl carbonate are mixed as the electrolyte of the nonaqueous electrolyte battery 1. A water electrolyte was prepared.
[0033]
The positive electrode 4 obtained as described above was accommodated in the positive electrode can 5, the negative electrode 2 was accommodated in the negative electrode can 3, and a porous polypropylene film separator 6 was disposed between the negative electrode 2 and the positive electrode 4. A non-aqueous electrolyte was poured into the negative electrode can 3 and the positive electrode can 5 and the negative electrode can 3 and the positive electrode can 5 were caulked and fixed to produce a 2025 type coin-type battery.
[0034]
< Reference Example > A positive electrode was produced in the same manner as in Example 1 except that MgMn ₂ O ₄ used as a positive electrode active material was produced by the solid phase method shown below, and a coin-type battery was produced in the same manner. . First, basic magnesium carbonate and manganese dioxide were mixed at a ratio of Mg: Mn = 1: 2, and heat treatment was performed at 800 ° C. for 5 hours. Thereafter, the mixture was cooled and mixed again, and then heat-treated again at 800 ° C. for 5 hours. After repeating this operation three times, an X-ray diffraction measurement was performed on a sample obtained by washing with distilled water. As a result, although not shown, an X-ray diffraction result similar to the result shown in FIG. Obtained. Therefore, the sample prepared by the above method is considered to be MgMn2O4. As described above, spinel-type MgMn ₂ O ₄ was obtained.
[0035]
<Comparative Example 1>
A positive electrode was produced in the same manner as in Example 1 except that V ₂ O ₅ was used as the positive electrode active material used for the positive electrode, and a coin-type battery was produced in the same manner.
[0036]
<Comparative example 2>
A positive electrode was produced in the same manner as in Example 1 except that MoO ₃ was used as the positive electrode active material used for the positive electrode, and a coin-type battery was produced in the same manner.
[0037]
Evaluation of batteries The results of evaluating these nonaqueous electrolyte batteries by the following test method are shown in Fig. 3. The nonaqueous electrolyte battery produced as described above was charged at a constant current of 100 mA / cm ² at 23 ° C., and after the battery voltage reached 3.0 V (vs. Mg ²⁺ / Mg), A constant current charge was performed, and the battery was fully charged when 4 hours had passed. Subsequently, constant current discharge was performed until the voltage became 0.0 V (vs. Mg ²⁺ / Mg). The above process was made into 1 cycle, this was repeated 10 cycles, and the discharge capacity was measured for each cycle. For the evaluation of the cycle characteristics, the capacity retention rate S (= C (N) / C () where the discharge capacity at the first cycle is the rated capacity C (1) and the discharge capacity at the Nth cycle is C (N). 1)) was used.
[0038]
As is clear from FIG. 2, compared to Comparative Example 1 and Comparative Example 2 using V ₂ O ₅ and MoO ₃ as the positive electrode active material, Example 1 using spinel type MgMn ₂ O ₄ as the positive electrode active material. It can also be seen that the nonaqueous electrolyte battery of Example 2 is superior in cycle characteristics. In addition, it was found that the positive electrode active material has better cycle characteristics than those in which a spinel type MgMn ₂ O ₄ produced by a solution method is produced by a solid phase method.
[0039]
【The invention's effect】
As described above in detail, according to the non-aqueous electrolyte battery using magnesium ions as a charge carrier according to the present invention, magnesium ions are diffused efficiently because ion conduction of magnesium ions in the positive electrode occurs two-dimensionally. Thus, improvement in cycle characteristics and load characteristics is realized. Furthermore, by simplifying the process of manufacturing the positive electrode, it is possible to reduce the cost for manufacturing the magnesium ion battery.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration example of a nonaqueous electrolyte battery according to the present invention.
FIG. 2 is an X-ray diffraction diagram showing an X-ray diffraction result of MgMn ₂ O ₄ .
FIG. 3 is a cycle characteristic diagram showing the relationship between the number of cycles and the capacity retention rate of a battery manufactured in an example.
[Explanation of symbols]
1 Nonaqueous electrolyte battery, 2 negative electrode, 3 negative electrode can, 4 positive electrode, 5 positive electrode can, 6 separator, 7 gasket

Claims (3)

A negative electrode including a negative electrode active material containing magnesium metal, a magnesium alloy or a material capable of occluding and releasing magnesium; and
A positive electrode including a positive electrode active material containing a magnesium manganese composite oxide represented by the general formula MgMn ₂ O ₄ ;
With a non-aqueous electrolyte,
The positive electrode active material is a non-aqueous electrolyte battery obtained by washing magnesium and manganese hydroxide obtained from a mixed solution of magnesium chloride and manganese chloride until the filtrate becomes neutral, and then firing at 700 to 900 ° C. . The nonaqueous electrolyte battery according to claim 1, wherein the nonaqueous electrolyte contains a compound represented by Mg (ClO ₄ ) ₂ . A negative electrode including a negative electrode active material containing a magnesium metal, a magnesium alloy or a material capable of occluding and releasing magnesium, and a positive electrode including a positive electrode active material containing a magnesium manganese composite oxide represented by the general formula MgMn ₂ O ₄ ; A non-aqueous electrolyte battery manufacturing method comprising a non-aqueous electrolyte,
A nonaqueous electrolyte battery comprising a step of washing a magnesium and manganese hydroxide obtained from a mixed solution of magnesium chloride and manganese chloride until the filtrate becomes neutral, and then firing at 700 to 900 ° C. to obtain a positive electrode active material. Manufacturing method.

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