JP3143715B2 - Rechargeable battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery. More specifically, the present invention relates to a lightweight, small, and high energy density secondary battery.

[0002]

2. Description of the Related Art Recently, BF ₄ ions, ClO ₄ ions, SbF ₄ ions, and PF ₆ ions have been added to polymer materials such as polyacetylene.
A method of reversibly doping an anion such as an ion, a Li ion, or a cation such as R ₄ N ion (R represents an alkyl group) has been found. The development of the secondary battery used for (1) has been actively conducted.

[0003]

However, a polymer material such as polyacetylene is a compound which is extremely unstable either by itself or in a doped state.
Therefore, a secondary battery using an electrode that overcomes these drawbacks has been desired.

[0004]

Means for Solving the Problems In view of the problems of the prior art, the present inventors have conducted intensive studies and as a result, solved the above problems by using fullerene semiconductors as electrode materials for secondary batteries. It has been found that the characteristics of a secondary battery can be improved by improving the stability of the present invention, and the present invention has been completed.

That is, the secondary battery of the present invention has a positive electrode,
A secondary battery comprising a negative electrode and an electrolyte, wherein the positive electrode is a fullerene semiconductor.

The fullerene used in the present invention is a recently discovered material known as a spherical carbon compound,
It is represented by a spherical carbon compound C ₆₀ having a soccer ball structure and a spherical carbon compound C ₇₀ having a rugby ball structure, and its basic properties are currently being elucidated. It is known that when the powder of the fullerene compound is subjected to heat treatment with an alkali metal in a reaction tube, an n-type semiconductor doped with the alkali metal can be formed. Recently, a fullerene compound obtained by adding an alkali metal to C ₆₀ , for example, K _X
C ₆₀ is known to Meissner effect occurs at 18K with 16K, a bulk thin film, also, such as Cs ₂ Rb ₁ C ₆₀ also critical temperature becomes superconductor at 33K, C ₆₀ is the next generation of new It is a material that has attracted much attention as a material.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of one embodiment of the present invention.
In the figure, 1 indicates a positive electrode, 2 indicates an electrolyte, 3 indicates a negative electrode, and 4 indicates a battery storage case.

The positive electrode 1 is made of a p-type fullerene semiconductor (or compound) doped with an anion. Negative electrode 3
Consists of an n-type fullerene semiconductor (or compound) doped with cations. It is not necessary to use a fullerene semiconductor for the negative electrode 3, and an electrode material used in a conventional secondary battery may be used. In particular,
Lithium metal or a lithium alloy can be used, and among them, lithium metal, aluminum-lithium alloy, and zinc-lithium alloy are particularly preferable.

The fullerene semiconductor (or compound, hereinafter sometimes simply referred to as a semiconductor) used is C
Either ₆₀ fullerene or C ₇₀ fullerene may be used, but more stable C ₆₀ fullerene is preferable. As a fullerene semiconductor used for an electrode material of a secondary battery, there are an n-type semiconductor doped with a cation and a p-type semiconductor doped with an anion. Using this n-type fullerene semiconductor as a negative electrode and the p-type fullerene semiconductor as a positive electrode 1,
A secondary battery is formed by sandwiching the electrolyte between these electrodes 1 and 3.

Cations serving as dopants for the n-type fullerene semiconductor include Li ions, Na ions, K ions, Cs ions, Rb ions, divalent Mg ions, and Al3 ions.
Examples of the anion which is a dopant of the p-type fullerene semiconductor such as a valence ion (aluminium trivalent ion) include BF
₄ ions, ClO ₄ ions, PF ₄ ions, AsF ₆ ions, CF ₃ SO ₃ ions, I ions, Br ions, Cl ions, F ions, etc., and the obtained battery has a high voltage and energy density. As the cation, an alkali metal ion such as Li ion, Na ion, K ion, Cs ion, or Rb ion is preferable because of its high cost, ease of synthesis, and low cost. preferable. Further, as the anion, BF ₄ ion, ClO ₄ ion, PF ₄ ion, CF ₃ ion
SO ₃ ions, I ions, Cl ions, and F ions are preferred, and BF ₄ ions, ClO ₄ ions, CF ₃ SO ₃ ions, I ions, and Cl ions are particularly preferred.

The fullerene compound powder to which lithium is added is placed in a glass container with a C ₆₀ powder obtained by separating and purifying soot obtained by discharging a graphite electrode, and lithium metal is added under an inert gas atmosphere. 40
It is obtained by firing at a temperature of about 0 ° C. for 24 to 84 hours. The addition amount of lithium metal is suitably 20 mol or less, particularly preferably 10 mol or less, per 1 mol of C ₆₀ .

When the fullerene semiconductor or fullerene compound shown in the present invention is used for the electrodes 1 and 3, the fullerene semiconductor or fullerene compound powder can be applied as a thin film by a method such as compression molding or a method such as vapor deposition. It can be molded to size.

Further, the fullerene semiconductor or the fullerene compound of the present invention is coated on a porous substrate, for example, with a surface area of 500.
~4000m ² / g approximately activated carbon fiber and activated carbon and 200-2000 m ² / g approximately carbon black supported on it can also be an electrode 1,3, electrodes 1,3 of this kind, the fullerene semiconductor It is formed by dispersing in an appropriate organic solvent, impregnating this in a porous substrate from a greenhouse at 100 ° C. for 10 minutes to 24 hours, and then drying and producing. Other carriers include graphite, graphitized carbon, manganese dioxide, and alumina.

As the electrolyte 2 used in the present invention, an electrolyte or a solid electrolyte in which a supporting electrolyte is dissolved in an organic solvent is used. Examples of the supporting electrolyte include a cation of a metal having an electronegativity of 1.6 or less and a salt of a cation such as an organic cation and an anion. Examples of the onium ion include a quaternary ammonium ion, a carbonium ion, and an oxonium ion. As anions, BF ₄ ion, CiO ₄ ion, PF ₄ ion, A
Examples include sF ₆ ion, CF ₃ SO ₃ ion, I ion, Br ion, Cl ion, and F ion.

As a specific example of the supporting electrolyte, LiB
F ₄ , LiClO ₄ , Et ₄ NBF ₄ , nBu ₄ NClO ₄ ,
LiI and the like can be mentioned, but not limited to these. As the organic solvent for dissolving the supporting electrolyte, an aprotic solvent having a high dielectric constant is preferable, and a nitrile, carbonate, ether, nitro compound, amide, sulfur-containing compound, chlorinated hydrocarbon, ketone, ester, or the like is used. Can be done. Representative examples of these include acetonitrile, propionitrile, propylene carbonate, ethylene carbonate, tetrahydrofuran,
Examples include, but are not limited to, 4-dioxane, nitromethane, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, and the like. The concentration of the electrolytic solution of the present invention is usually 0.001 to 10
It is used at a mole / liter, preferably 0.1 to 2 mole / liter.

Further, as the solid electrolyte, for example, R
_{b 4 Cu 16 I 7 Cl 13} , Rb 3 Cu 7 Cl 10 , such as copper ion conductive solid _{electrolyte, RbAg 4 I 5, Ag 3} SBr silver ion conductive solid electrolyte such _{as, LiI, Li 3 N, Li} 2 SO
_{4, Li 4 SiO 4, LISICON} ( Li superionic _{conductor: xLi 4 GeO 4 - (1} -x) Zn 2 GeO 4: x =
Examples thereof include a lithium ion conductive solid electrolyte such as 3/4), and a copper ion conductive solid electrolyte and a silver ion conductive solid electrolyte have a low open-circuit voltage of the battery and have low practical value. These silver ion conductive solid electrolytes and copper ion conductive solid electrolytes have relatively low decomposition temperatures. For example, RbAg ₄ I ₅ is around 228 ° C. and Rb ₄ Cu ₁₆ I ₇ C
Since l ₁₃ is decomposed and melted at about 234 ° C., a lithium ion conductive solid electrolyte which is difficult to decompose is preferable.

The solid electrolyte may be used alone, such as a sintered body or a thin film, or may be an elastic polymer dispersed as a binder. As the polymer elastic body, generally known polymer resins, for example, polyethylene resin, polypropylene resin, silicone resin, vinyl chloride resin, ABS (acrylonitrile butadiene.
Resins such as (styrene) resin, phenol resin, polyurethane, polyamide, polycarbonate, ionomer resin, and fluororesin can be used.

In the present invention, in the electrolytic solution, glass, Teflon, polyethylene, plate or the like having a saw-shaped or perforated shape for fixing the electrode may be used. Further, a porous membrane such as glass filter paper, Teflon, polyethylene, polypropylene and nylon may be used as the diaphragm.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.

[0021] to give a C ₆₀ powder by separation and purification from soot obtained by discharging the embodiment 1 of graphite electrodes.

From this powder, 30 C ₆₀ fullerene semiconductors were
0 mg, and the diameter is 10 with a tableting machine for infrared spectrum.
The disk was molded into a disk having a diameter of 2 mm, a platinum wire was pressure-bonded to the disk, wrapped with a glass filter, and sandwiched with a 20 mm square Teflon plate having holes of 3 mm in diameter at regular intervals to obtain a positive electrode. A negative electrode was similarly manufactured. Both electrodes were immersed in a 1 mol / liter solution of LiBF ₄ in 20 ml of acetonitrile to produce a semiconductor secondary battery.

The open-ended voltage (Voc) and the short-circuit current (Isc) at the start of discharging of this secondary battery were 9 V and 20 mA, respectively.

[0024] In the same manner as in Example 1, and the C ₆₀ powder obtained by separation and purification from soot obtained by discharging the graphite electrode, metal lithium was cut to a size of 0.5~1mm Was placed in a Pyrex glass container and calcined at 400 ° C. for 72 hours under an argon gas atmosphere to obtain a C ₆₀ fullerene compound to which lithium was added.

[0025] was molded positive electrode material in the C ₆₀ fullerene compound in the same manner as disc-shaped as in Example 1. A lithium metal foil was used for the negative electrode. A lithium secondary battery was manufactured in the same manner as in Example 1 except for the electrolytic solution and other conditions.

The open-end voltage (Voc) and the short-circuit current (Isc) of the lithium secondary battery at the start of discharging are each 3.
9 V and 17 mA.

[0027]

Since the secondary battery of the present invention uses a chemically stable fullerene semiconductor, it is a stable secondary battery having a long cycle life and very little self-discharge. Further, since it can be reduced in size and weight and can be manufactured in any shape, it is most suitable for a secondary battery in the field of information and electronic materials.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Electrolyte 3 Negative electrode 4 Battery storage case

Claims (4)

(57) [Claims] 1. A secondary battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode is a fullerene semiconductor. 2. A secondary battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode comprises a lithium-doped fullerene semiconductor, and the negative electrode comprises at least one metal selected from lithium metal, aluminum-lithium alloy and zinc-lithium alloy. A secondary battery, comprising: 3. The secondary battery according to claim 2, wherein the secondary battery is a fullerene semiconductor having a lithium doping amount of 10 mol% or less. 4. C having a lithium doping amount of 10 mol% or less.
_The secondary battery according to claim 2, wherein the secondary battery is a ₆₀ fullerene semiconductor.