JPH0439863A - Secondary battery electrode - Google Patents

Abstract

PURPOSE:To obtain a high capacity of electrode, excellent charge and discharge cycle property and flexibility by forming specific carboneous material and carrier to carry alkaline metal as active material thereon. CONSTITUTION:Carrier composed of carboneous material, satisfied by the ratio of hydrogen atoms to carbon atoms being less than 0.15, face-to-face spaces being 3.37Angstrom or wider by a x-ray wide-angle diffracting method and the sizes of crystallites in a (c)-axial direction being 220Angstrom or smaller, metal to form alloy with active material or alloy grains containing active material and organic polymeric fiber of which the clad has a lower melting or softening point than the core is formed to carry alkaline metal as active material thereon. It is thus possible to obtain a flexible electrode for a secondary battery with a high capacity and excellent charge and discharge cycle property.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electrode for a secondary battery that has a high capacity and excellent charge/discharge characteristics. More specifically, the present invention relates to a flexible alkali metal secondary electrode that can be used as a spiral electrode to configure a cylindrical secondary battery or as a thin sheet-shaped electrode to configure a sheet-type secondary battery.

(Prior art) It has been proposed to use conductive polymers such as polyacetylene as electrodes for lithium secondary batteries, but conductive polymers are dependent on the amount of Li ion doping, that is, the electrode capacity and stable charge/discharge characteristics. Missing.

Furthermore, attempts have been made to use lithium metal in the negative electrode of lithium secondary batteries, but in this case the charge/discharge cycle characteristics become extremely poor.

That is, when the battery is discharged, lithium from the negative electrode body becomes Li ions and moves into the electrolyte solution, and during charging, these Li ions become metallic lithium and are deposited on the negative electrode body again.
When this charge/discharge cycle is repeated, the metal lithium deposited along with it becomes dendrite-like. Since this dendrite-like metallic lithium is an extremely active substance, it causes the electrolyte to decompose, resulting in a disadvantage that the charge/discharge cycle characteristics of the battery deteriorate. If this continues to grow, the dendrite-like metal lithium deposits will eventually penetrate the separator and reach the positive electrode body, causing a problem of short-circuiting. In other words, the problem arises that the charge/discharge cycle life is short.

In order to avoid such problems, attempts have been made to construct a negative electrode by using a carbonaceous material obtained by baking an organic compound as a carrier, and supporting an alkali metal, mainly lithium, as an active material on this carrier. By using such a negative electrode, the charge/discharge cycle characteristics of the negative electrode are dramatically improved. However, on the other hand, the negative electrode molded body using this carbonaceous material as a carrier has poor flexibility and is not easily formed into a sheet. A satisfactory fall or spiral electrode could not be obtained.

(Problems to be Solved by the Invention) Against this technical background, the present invention aims to provide a negative electrode for a secondary battery that has a large electrode capacity, excellent charge/discharge cycle characteristics, and flexibility. This is the purpose.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present inventors have conducted extensive research on negative electrodes, and have found that it is possible to form an alloy with a carbonaceous material and an active material. An electrode structure in which an active material is supported on a support made of a mixture of a metal or an alloy containing an active material and a fibrous organic polymer having a multilayer structure of a core and a cladding. Accordingly, the present invention was found to be extremely effective for achieving the above-mentioned object, and the present invention was achieved.

That is, the electrode of the present invention has the following characteristics: (a) the hydrogen/carbon atomic ratio is less than 0.15, and (b) the interplanar spacing (d) of the (002) plane measured by X-ray wide-angle diffraction
,. 2) a carbonaceous material satisfying 337 Å or more and a crystallite size (Lc) in the C-axis direction of 220 Å or less, (2) a particle of a vine metal forming an alloy with an active material or an alloy containing an active material, and (3) ) A carrier made of organic polymer fibers having a multilayer structure of a core and a sheath, with the sheath having a lower melting point or softening point than the core, is formed, and an alkali metal is supported as an active material on this support. Features.

The secondary battery electrode of the present invention is characterized by a negative electrode having the above-described configuration, and other elements can be configured in the same manner as conventional secondary battery electrodes.

In the negative electrode according to the present invention, the active material is an alkali metal, preferably lithium. For example, in the case of lithium, this active material repeatedly changes into Li ions and metallic lithium as the battery is charged and discharged.

In the present invention, the carbonaceous material used as a support for the active material constituting the electrode body has (a) a hydrogen/carbon atomic ratio (H/C) of less than 0.15;
and (b) the spacing (d) of the (002) plane by X-ray wide-angle diffraction method
o. 2) is 3.37 Å or more and the crystallite size (Lc) in the C-axis direction is 220 Å or less; The carbonaceous material preferably contains other atoms such as nitrogen, oxygen, halogen, etc. in an amount of 7 mol% or less, more preferably 4 mol% or less, particularly preferably 2 mol% or less.
It may be present in a proportion of less than mol%.

H/C is preferably less than 010, more preferably 00
It is less than 7, particularly preferably less than 0.05.

The interplanar spacing (do. 2) of the (002) plane is preferably 3.3
8 Å or more, more preferably 339 to 3.75 people, even more preferably 3.41 to 3.70 people, particularly preferably 3.
45 to 3.70 people. Crystallite size L in the C-axis direction
c is preferably 180 Å or less, more preferably 5 to 15
0 person, more preferably 10 to 80 people, particularly preferably 12 to 70 people.

These parameters, namely H/C, do. If either 2 or Lc deviates from the above range, the overvoltage at the electrode body during charging and discharging will increase, and as a result, gas will be generated from the electrode body, significantly impairing the safety of the battery. In addition, the charge/discharge cycle characteristics also deteriorate.

Furthermore, it is preferable that the carbonaceous material used for the carrier of the electrode body according to the present invention has the following characteristics.

That is, in Raman spectrum analysis using argon ion laser light with a wavelength of 5145, the G value defined by the following formula is preferably less than 2.5,
More preferably less than 2.0, particularly preferably 0
．． 2 or more and less than 1.2.

Here, the G value is the wavelength of 5145 for the carbonaceous material mentioned above.
In the spectrum intensity curve recorded on the chart when Raman spectrum analysis was performed using human argon ion laser light, the integral value (area intensity) of the spectrum intensity within the range of wave number 1580 ± 100 cm-' is calculated as wave number 1
It refers to the value divided by the area intensity within the range of 360±100 cm-', and corresponds to a measure of the degree of graphitization of the carbonaceous material.

That is, this carbonaceous material has a crystalline portion and an amorphous portion, and the G value can be said to be a parameter indicating the ratio of the crystalline portion in this carbonaceous structure.

Furthermore, it is desirable that the carbonaceous material used for the carrier of the electrode body according to the present invention satisfies the following conditions:
That is, the distance iiia is twice the interplanar spacing dzo of (110) in X-ray wide-angle diffraction analysis.

(2d, .) is 2.38 to 2.47 people, more preferably 2.39 to 2.46 people; the crystallite size La in the C-axis direction is preferably 1oA or more, more preferably 15
The range is from 150 people to 150 people, particularly preferably from 19 to 70 people.

Furthermore, this carbonaceous material can take any form such as granular or fibrous, but granular or fibrous forms are preferable.

As for the granules, the volume average particle size is preferably 300P or less, more preferably 0.2P or more and 200P or less, even more preferably 0.5F or more and 150J7'll or less, particularly preferably 2P or more and 100P or less, and most preferably 5P or more. The particles are 60P or less.

Furthermore, this carbonaceous material has pores inside, and the total pore volume is preferably 1.5 x 10-"d/g or more, more preferably the total pore volume is 2.Qxlo
-"11d!/g or more, more preferably 3, OX
10-"-/g or more and 8x1o-/g or less, particularly preferably 4.0xlO-"d/g or more and 3 x 1O-"d
/g or less.

The total pore volume and the average pore radius described below are determined by measuring the amount of gas adsorbed to the sample (or the amount of gas desorbed) under several equilibrium pressures using the constant volume method. Determined by measuring the amount of gas.

The total pore volume is determined from the total amount of gas adsorbed at a relative pressure P/P = 0.995, assuming that the pores are filled with liquid nitrogen.

P Vapor pressure of adsorbed gas (mmHg) Po Saturated vapor pressure of adsorbed gas at cooling temperature (mmHg) Furthermore, from the amount of nitrogen gas adsorbed (~ヮ68), the following (1)
The amount of liquid nitrogen filled in the pores fvzq using the formula
) to determine the total pore volume.

p, v,,,v,.

VlIQ= (1)
T Here, P and T are atmospheric pressure (kgf/cm”)
) and temperature ('K), and v6 is the molecular volume of the adsorbed gas (34.7 cm''/mol for nitrogen).

Further, the carbonaceous material used for the carrier of the electrode body according to the present invention has pores inside, and the average pore radius (γ2) is 8.
It is preferable that the number of participants is 100 to 100 people. More preferably 10
~80 people, more preferably 12-60 people, particularly preferably 14-40 people.

The average pore radius (γ,) is V determined from equation (1) above.
From liq and BET specific surface area S; it is determined by calculation using the following equation (2).

Here, it is assumed that the pore is cylindrical.

The above-mentioned carbonaceous materials can be obtained by carbonizing organic compounds by heating and decomposing them at a temperature of 300 to 3000°C under a flow of inert gas. Examples of starting organic compounds include cellulose and phenol. Resin: Polyacrylonitrile, poly (α-halogenated acrylonitrile)
Acrylic resins such as; polyvinyl chloride, polyvinylidene chloride, chlorinated polyvinyl chloride and other halogenated vinyl resins; polyamideimide resins; polyamide resins; polyacetylene, poly(p-phenylene) and other conjugated resins; Organic polymer compounds: naphthalene, phenanthrene, anthracene, triphenylene, pyrene, chrysene, naphthacene, vicene, perylene, pentaphene,
A fused cyclic hydrocarbon compound formed by condensing two or more monocyclic hydrocarbon compounds with three or more members such as pentacene,
or derivatives of the above compounds such as carboxylic acids, carboxylic acid anhydrides, and carboxylic acid imides Various pitches based on mixtures of the above compounds; indole, isoindole, quinoline, isoquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine , a fused heterocyclic compound formed by at least two or more 3-membered or more-membered monocyclic compounds such as phenanthrene bonded to each other, or bonded to one or more 3- or more-membered monocyclic hydrocarbons: each of the above Derivatives of compounds such as carboxylic acids, carboxylic acid anhydrides, carboxylic acid imides; and also benzene or its derivatives such as carboxylic acids, carboxylic acid anhydrides, carboxylic acid imides, such as 1,2,4,5-tetracarboxylic acid. , its dianhydride, or its diimide and other derivatives.

Alternatively, a carbonaceous substance such as carbon black or coke may be used as a starting source and further heated to appropriately advance carbonization to form the carbonaceous substance constituting the carrier of the electrode body according to the present invention.

The carrier constituting the secondary battery electrode of the present invention includes the above-mentioned carbonaceous material, a metal capable of forming an alloy with the active material, an alloy containing the active material, and a fiber having a multilayer structure of a core and a sheath. It consists of a mixture of organic polymers.

As the active material, an alkali metal, preferably lithium, is used. It is further preferred to use an alloy of lithium or to use lithium in combination with a metal with which it can be alloyed.

For example, in the case of a lithium alloy, the composition (molar composition) of the alloy is 0M expressed as L i xM (where X is the molar ratio to gold ff1M). Examples of metals used include aluminum (Aff), Lead (pb),
Zinc (Zn), tin (Sn), bismuth (Bi), indium (In), magnesium (Mg), gallium (G
a), cadmium (Cd), silver (Ag), silicon (Si
), boron (B), gold (Au), platinum (pt), palladium (Pd), antimony (sb), etc., preferably A, pb, In, Bi and Cd, more preferably AI2 , Pb, and In, and particularly preferably Aff.

In addition to the above-mentioned metals, the alloy may further contain other elements in an amount of 50 mol% or less.

In Li and M, X preferably satisfies 0<x≦9, more preferably 0.1≦X≦5, still more preferably 0.5≦X≦3, particularly preferably 07≦
X≦2.

As the active material alloy (Li, M), one type or two or more types of alloys can be used.

As the metal that can be alloyed with the active material, one or more of the above metals M can be used.

The metal (M) that can be alloyed with the active material or the alloy containing the active material (LixM) exists in the form of particles or attached to the above-mentioned carbonaceous material.

The mixed composition of the above-mentioned carbonaceous material and a metal (M) capable of forming an alloy with the active material or an alloy of the active material (LixM) is as follows: Possible alloys of metals or active materials, preferably 7
0 parts by weight or less, more preferably 2 parts by weight or more and 60 parts by weight or less, even more preferably 5 parts by weight or more and 50 parts by weight or less,
Particularly preferably 10 parts by weight or more and 45 parts by weight or less, most preferably 15 parts by weight or more and 40 parts by weight or less.

The volume average particle diameter of such metal particles is preferably 0.2P or more and 200P or less, more preferably 0.3F or more and 150P or less, and even more preferably 0.5P or more and 100P or less.
, particularly preferably 1P or more and 60F or less.

Furthermore, it is also possible that a metal (M) or an alloy of the active material (LixM) that can form an alloy with the active material exists in the form of a thin layer coated on the surface of the aforementioned carbonaceous material particles. It is.

Alternatively, a metal (M) that can form an alloy with the active material in a form that is included inside the particles of the carbonaceous material mentioned above.
It is also possible that alloys (LixM) containing active materials are present.

An alloy containing a metal (M) or an active material (LixM) that can form an alloy with a particulate active material and the above-mentioned carbonaceous material particles or those having a fibrous form, etc. Can be mixed with.

Further, as a method for coating such a metal as a thin layer, a vapor deposition method, a plating method, a thermal spraying method, etc. are used.

Furthermore, as a method for incorporating the metal (M) that can be alloyed with the active material or the alloy of the active material (LixM) inside the particles of the carbonaceous material, gold E
A method of impregnating and thermally decomposing an organic metal compound of (M), thermally decomposing an organic compound using gold K (M) particles as a core,
A method such as carbonization is used.

The carrier constituting the secondary battery electrode of the present invention is a mixture of the above-mentioned carbonaceous material and a metal (M) capable of forming an active material or an alloy (LixM) containing the active material. These organic polymers are bound together in an entangled manner to maintain their shape as a carrier. Furthermore, the organic polymer fiber has a two or more layer structure consisting of a core part and a sheath part, and an organic polymer with a low melting point or softening point is used for the outermost layer of the sheath part, and this is bonded by thermocompression. By doing so, the shape retention of the carrier can be made stronger and more flexible.

Organic polymeric fibers consist of at least two organic polymeric components, usually two organic polymeric components,
Each of them constitutes a core part and a sheath part surrounding it. Usually, it has a two-layer structure of a core part and a sheath part, but it can also have a multilayer structure in which the sheath part has two or more layers.

The organic polymer that is a component of the fiber used in the core has a higher melting point or softening point than the organic polymer that is a component of the sheath surrounding the core.

Further, when the sheath is composed of two or more layers, the organic polymer in the outermost layer is composed of one having the lowest melting point or softening point.

Organic polymers include polyethylene, polypropylene,
Copolymers of ethylene and α-olefins having 3 to 12 carbon atoms, copolymers of propylene and ethylene, copolymers of propylene and α-olefins having 4 to 12 carbon atoms, copolymers of ethylene and vinyl acetate Polymers, polyester resins such as polyethylene terephthalate, polyamide resins, etc. are used, and the combination of the fiber core material and sheath material used in the present invention is selected from these organic polymers.

Note that it is preferable that an organic polymer containing fluorine atoms not be used in the outermost layer of the sheath portion constituting the fiber.

This is not preferable because the fluorine atoms in the organic polymer may react with the alkali metal that is the active material.

The organic polymer fiber preferably has an average diameter of 30- or less,
It is more preferably 2OF or less, still more preferably 15F or less, and most preferably IOF or less. The average length of the fibers is preferably 100 mm or less, more preferably 70 mm or less.
mm or less, more preferably 0.3 mm or more and 50 mm or less, particularly preferably 0.5 mm or more and 20 mm or less, and most preferably 0.7 mm or more and 5 mm or less.

A particularly preferable form of the fibrous organic polymer is that the fibers are less than 1011'l11, more preferably 5P or less, especially 3
It consists of fine fibers (fibrils) with an average diameter of P or less.

Alternatively, the organic polymer fibers may be in the form of a fibrid (powder having tentacle-like ultrafine fibrils).

In any case, the average diameter of the organic polymer fibers is preferably at most % of the average particle diameter of the carbonaceous material particles, more preferably at most %, even more preferably at least %OO and at most 0, particularly preferably at least Z0 and at most It is.

Further, when the carbonaceous material is also fibrous, the average fiber diameter of the organic polymer fibers is preferably at most % of the average diameter of the fibers of the carbonaceous material, more preferably at most Z, and even more preferably at Zo.
. It is preferably z0 or more and z% or less, and particularly preferably z0% or more and z% or less.

The ratio of the core and sheath of the organic polymer fiber can be set arbitrarily, but preferably the diameter of the core is between Z0 and 0 of the diameter of the fiber, more preferably between % and Z0, and Preferably, the number is at least 70 stations and at most 70 stations.

The amount of the organic polymer fiber is preferably 40 parts by weight or less, more preferably 1 part by weight or more and 30 parts by weight or less, and even more preferably 0. The amount is 2 parts by weight or more and 20 parts by weight or less, particularly preferably 0.3 parts by weight or more and 10 parts by weight or less, and most preferably 0.5 parts by weight or more and 7 parts by weight or less.

The above-mentioned carbonaceous material may take any form such as particulate or fibrous form as described above, but particulate form is preferable. A mixture of this carbonaceous material, a metal that can be alloyed with the active material, or an alloy of the active material, and organic polymer fibers are mechanically mixed and formed into a sheet-like electrode by a processing method such as roll molding or compression molding. can do.

During molding, a wire mesh made of metal such as nickel is used as a current collector and support, and it can be pressed onto the wire mesh to form a sheet-like electrode.Methods for supporting the active material on the support include chemical methods and electrochemical methods. For example, a carrier is immersed in an electrolytic solution containing a predetermined concentration of alkali metal cations, preferably L1 ions, and lithium is used as a counter electrode, and the carrier is used as an anode for electrolysis. A method of impregnation, a method of mixing an alkali metal powder, preferably a powder of lithium or a lithium alloy, in the process of obtaining a molded support body, etc. can be applied.

Alternatively, a sheet of an alkali metal, preferably lithium, is laminated to a molded support to form an electrode, which is incorporated into a battery and then charged and discharged to support the alkali metal, preferably lithium.

The amount of the alkali metal, preferably lithium, supported on the negative electrode support in advance in this way is preferably 0.030 parts by weight or more and 0.250 parts by weight or less, more preferably 0.060 parts by weight, per 1 part by weight of the support. 0.20 or more
Part by weight or less, more preferably 0.070 part by weight or more
．． The amount is 15 parts by weight or less, particularly preferably 0.075 parts by weight or more and 0.12 parts by weight or less, and most preferably 0.080 parts by weight or more and 0.100 parts by weight or less.

The secondary battery electrode of the present invention is usually used as a negative electrode, and is opposed to a positive electrode with a separator interposed therebetween.

Since the secondary battery electrode of the present invention has excellent flexibility and bending strength, it can be applied as an electrode for various sheet-shaped, prismatic, and cylindrical batteries.

For example, as shown in Fig. 1, a positive electrode body (1) and a negative electrode body (2) of the present invention are rolled into a spiral shape so as to face each other with a separator (3) interposed therebetween, and this is housed in a cylindrical can. , it can be a cylindrical secondary battery.

This positive electrode body is preferably made of a metal chalcogen compound that releases or acquires alkali metal cations such as Li ions during charging and discharging reactions, for example, but not limited to, such metal chalcogen compounds include Vanadium oxide, vanadium sulfide, molybdenum oxide, molybdenum sulfide, manganese oxide,
Examples include chromium oxides, titanium oxides, titanium sulfides, and composite oxides and composite sulfides thereof. Preferably, Cr s Os , V 0's, VsO+
-1VOt,CTaOs,Mn0t,Tie,,
M OV x Os, T i S *, V − S s,
Mo Ss, Mo Ss, V Ss, Cr
o, m5Va, yiS2, Cro, s V(1, I
S etc. Also, LiCOO! , oxides such as WOs, (, uS, F eo, xsVo, yiS*, N
ao, + CrS! Sulfides such as N i PSs, F
Phosphorus, ionic compounds such as ePSs, V S e x, N
Selenium compounds such as bSe s can also be used.

Further, conductive polymers such as polyaniline and polypyrrole can be used.

The separator that holds the electrolyte is made of materials with excellent liquid retention.
For example, it is made of a nonwoven fabric made of polyolefin resin. This separator contains propylene carbonate, 1
．． In an aprotic organic solvent such as 3-dioxolane or 1゜2-dimethoxyethane,
B F 4, L i A s F a, L i P F
It is impregnated with a non-aqueous electrolyte at a predetermined temperature in which an electrolyte such as s is dissolved.

Furthermore, a solid electrolyte that is a dielectric of alkali metal cations such as Li ions can be interposed between the positive electrode body and the negative electrode body.

(Function) In a secondary battery configured in this way, active material ions are supported on the carrier at the time of charging in the negative electrode, and active material ions in the carrier are released at the time of discharging, so that the charge/discharge electrode is The reaction progresses.

On the other hand, in the positive electrode, when a metal chalcogen compound is used, active material ions are released into the positive electrode body during charging, and the active material ions are supported during discharging, thereby progressing the electrode reaction of charging and discharging.

Alternatively, when a conductive polymer such as polyaniline is used for the positive electrode, the counter ions of the active material ions are supported on the positive electrode body during charging, and the counter ions of the active material ions are released from the positive electrode body during discharging. The reaction progresses.

A battery reaction accompanying charging and discharging of a battery proceeds by such a combination of electrode reactions of the positive electrode body and the negative electrode body.

(Effects of the Invention) The secondary battery electrode of the present invention has the above-mentioned carbonaceous material particles, particles of a metal alloy forming an alloy with an active material or an alloy containing an active material, and a multilayer structure of a core part and a sheath part. However, on a carrier made of an organic polymer wire whose sheath part has a lower melting point or softening point than the core part,
By supporting an alkali metal, preferably lithium, as an active material, it can be shaped into a flexible sheet electrode, which can then be spirally applied to a cylindrical secondary battery. It can also be applied as an electrode for thin sheet batteries or square batteries. Therefore, the present invention provides an electrode that enables a secondary battery with high capacity, high output, and excellent charge/discharge cycle characteristics.

(Examples) Hereinafter, the present invention will be explained by Examples and Comparative Examples. Note that the present invention is not limited to this example.

In the present invention, elemental analysis and wide-angle X-ray diffraction measurements were carried out by the following methods.

[Elemental analysis] The sample was dried under reduced pressure at 120° C. for about 15 hours, and then dried at 100° C. for 1 hour on a hot plate in a dry box. The CO generated by combustion was then sampled in an aluminum cup in an argon atmosphere.
, the carbon content from the weight of the gas, and the generated H2O
Determine the hydrogen content from the weight of. In the Examples of the present invention described later, measurements were made using a PerkinElmer 240C elemental analyzer.

"X-ray wide-angle diffraction" (1) Interplanar spacing (d, .2) of (002) plane and (11
0) Interplanar spacing (dl, .) If the carbonaceous material is a powder, it is used as it is, or if it is in the form of minute pieces, it is powdered in an agate mortar, and high-purity silicon for X-ray standards is added at about 15% by weight based on the sample. The powder is added and mixed as an internal standard substance, packed into a sample cell, and a wide-angle X-ray diffraction curve is measured by a reflection diffractometer method using a CuKa ray made monochromatic with a graphite monochromator as a radiation source. To correct the curve, the following simple method is used without making corrections regarding so-called Lorentz, polarization factors, absorption factors, atomic scattering factors, etc. That is, by drawing the baseline of the curve corresponding to (002) and (110) diffraction, and replotting the real intensity from the baseline, the (002) plane and (l
l Obtain the correction curve for the O) surface. Find the midpoint of the line segment where a line parallel to the angular axis drawn at two-thirds of the peak height of this curve intersects with the diffraction curve, correct the angle at the midpoint using an internal standard, and calculate this. Do by the following Bragg equation from the wavelength λ of the CuKa line. 2 and d. seek.

λ+1.5418 people θ, θ: doox, dll. The diffraction angle corresponding to (2
) Crystallite size in c-axis and a-axis directions = Lc ; L
a In the corrected diffraction curve obtained in the previous section, the size of the crystallite in the C-axis and a-axis directions is determined from the following equation using the so-called half-width β at a position half the peak height.

β · cos θ Although there are various discussions regarding the shape factor K, K=090 was used. θ, and θ' have the same meanings as in the previous section.

Example 1 (1) Synthesis of carbonaceous material Granules of crystalline cellulose (average radius of about 100 yen) were set in an electric heating furnace, heated to 1000°C at a rate of 250"C/hour under nitrogen gas flow, and further heated. It was held at 1000°C for 1 hour.

Thereafter, the obtained carbonaceous material particles were set in another electric furnace and heated to 1800°C at a heating rate of 1000°C/hour under nitrogen gas flow, and further maintained at 1800°C for 1 hour. .

The carbonaceous material thus obtained was placed in a 500-mm agate container, two agate poles with a diameter of 30 mm, and a diameter of 25 m.
6 agate balls with a diameter of 20 mm and 16 agate balls with a diameter of 20 mm were added and crushed for 3 minutes.

The obtained carbonaceous material had the following characteristics as a result of elemental analysis, analysis such as X-ray wide-angle diffraction, and measurement of particle size distribution, specific surface area, etc.

Hydrogen/carbon (atomic ratio) = Q, 04 do. , = 3.59 people, Lc = 14 people aa (2dl+.) = 2.41. La = 25 people Volume average particle diameter = 40P Specific surface area (BET) = 8.2 m"/g (2) Preparation of mixture of carbonaceous material and aluminum particles Volume average particle size for 100 parts by weight of the above carbonaceous material particles 30 parts by weight of aluminum particles having a diameter of 15F were added and mixed mechanically.

(3) The molded core of the sheet-like carrier is polyester with a melting point of 250°C, and the sheath part is a polyester with a melting point of 110°C.
Diameter 2 denier, with two layers of polyethylene in °C
10 parts by weight of composite fibers with a cut length of 5 were added to 100 parts by weight of the above mixture of carbonaceous material and aluminum particles, and mixed mechanically. While rolling this with a roll,
It was pressed onto a 0.00 mesh nickel wire gauze at a temperature of 120°C to form a sheet-like support with a thickness of 0.4 mm.

(4) Supporting lithium on the above-mentioned support Using the above-mentioned support as one electrode and lithium metal as the counter electrode, the active material is electrolytically treated in a propylene carbonate solution of 1 mol/I2 of Li CI204. A negative electrode body was manufactured by supporting lithium. The electrolytic treatment conditions were a bath temperature of 20° C., a current density of 0, and 7 mA/cm'', and lithium equivalent to 830 mAh was supported on the negative electrode body.

(5) Manufacture of positive electrode body 10g of Mn0f powder calcined at 470°C and powdered polytetrafluoroethylene Ig. The mixed wire material thus obtained was roll-formed into a sheet having a thickness of 0.4 mm.

(6) Battery assembly A sheet-like electrode in which lithium is supported on a carrier made of a mixture of the above-mentioned carbonaceous material, aluminum particles, and composite fibers is interposed with a polypropylene nonwoven fabric as a separator, and the above-mentioned M n is used as the positive electrode. Sheet electrodes made of Ox were laminated, rolled into a spiral shape as shown in FIG. 1, and housed in a stainless steel cylindrical can.

The separator was impregnated with a 1 mol LiCJO4/β-propylene carbonate solution, the battery cell was sealed, and a battery cell as shown in FIG. 1 was assembled.

(7) Characteristics of the battery The battery thus produced was discharged at a constant current of 20 mA until the battery voltage reached 1.0 . Then, charge the battery with a constant current of 20 mA until the battery voltage reaches 3.3 V, and then perform preliminary charging and discharging for 5 cycles with a constant current of 20 mA and a potential control with an upper limit of 3.3 V and a lower limit of 1.8 V. carried out.

Thereafter, charging and discharging were repeated between 3.3 V and 1.8 V at a constant current of 25 mA, and cycle evaluation was performed. Table 1 shows the performance at the 6th cycle and the 60th cycle.

Comparative Example 1 A battery was constructed in the same manner as in Example 1 except that a lithium metal sheet was used instead of the negative electrode in Example 1.

The characteristics of the battery are shown in Table 1.

While the coulombic efficiency at the 60th cycle significantly decreased in Comparative Example 1, no change was observed in Example I compared to the 6th cycle.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of a battery of Example 1. ■... ・Positive electrode body 2...Negative electrode body 3...Separator (including electrolyte)

Claims (1)

[Claims] 1. (1) The following characteristics (a) The hydrogen/carbon atomic ratio is less than 0.15, and (b) The interplanar spacing (d) of the (002) plane measured by X-ray wide-angle diffraction
_0_0_2) is 3.37 Å or more and the crystallite size (Lc) in the c-axis direction is 220 Å or less; (2) particles of a metal that can form an alloy with an active material or an alloy containing an active material; (3) A carrier made of organic polymer fibers having a multilayer structure of a core and a sheath, the melting point or softening point of which is lower than that of the core, is formed, and an alkali metal is supported on this as an active material. A secondary battery electrode characterized by: