JPH0439862A - Secondary battery electrode - Google Patents

Abstract

PURPOSE:To obtain a high capacity of electrode, excellent charge and discharge property and flexibility by forming grain material, for which polymeric elastomer is attached to the surface of specific carboneous grains, and carrier to carry alkaline metal as active material thereon. CONSTITUTION:Carrier composed of grain material for polymeric elastomer is attached to the surface of carboneous grains, satisfied by the ratio of hydrogen atoms to carbon atoms being less then 0.15, face-to-face spaces being 3.37Angstrom or wider by a x-ray wide-angle diffracting method and the size of crystallites in a (c)-axial direction being 180Angstrom or smaller, and metal to form alloy with active material or alloy grains containing active material is formed to carry alkaline metal as active material thereon. It is thus possible to 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 battery 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.

In other words, when the battery is discharged, lithium is removed from the negative electrode body.
It becomes ions and moves into the electrolyte, and during charging, this Li
The ions become metallic lithium and are deposited on the negative electrode body again, but when this charging/discharging cycle is repeated, the metallic lithium deposited becomes dendrite-like. Since this dendrite-like metallic lithium is an extremely active substance, it decomposes the electrolyte, 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. If you draw it separately,
This results in the problem of short charge/discharge cycle life.

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, particularly lithium, as an active material on this carrier. By using such a negative electrode, the charge-discharge cycle characteristics are dramatically improved. However, on the other hand, the negative electrode molded body using this carbonaceous material as a carrier has poor flexibility and does not form in a sheet-like or spiral shape. A satisfactory 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 intensive research on negative electrodes, and as a result, they have developed a method of attaching a polymer elastomer to the surface of a carbonaceous material. When an electrode is constructed in which an active material is supported on a support made of a mixture of particles of a metal capable of forming an alloy with the above-mentioned active material or of an alloy containing the active material, the above-mentioned The present invention has been achieved based on the discovery that the method is extremely effective for achieving the purpose of the invention.

That is, the secondary battery electrode of the present invention has the following characteristics: (1) the hydrogen/carbon atomic ratio is less than 0.15, and (b) the interplanar spacing of the (002) plane as determined by X-ray wide-angle diffraction ( d
,. 2) particles with a polymer elastomer attached to the surface of carbonaceous material particles satisfying 3.37 Å or more and a crystallite size (Lc) in the C-axis direction of 180 Å or less, and (2) an active material and an alloy. The present invention is characterized in that a carrier is formed of particles of an alloy containing a metal or an active material that can be formed, and an alkali metal is supported as an active material on this carrier.

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 L1 ion 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 interplanar spacing (d
002) is 337 Å or more and the crystallite size (Lc) in the C-axis direction is 180 Å or less. mol% or less, more preferably 4 mol%
Hereinafter, it may be present in a particularly preferably proportion of 2 mol% or less.

H/C is preferably less than 0.10, more preferably 0
It is less than 07, particularly preferably less than 005.

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 34
5 to 3.70 people.

The crystallite size Lc in the C-axis direction is preferably 150 Å or less, more preferably 5 to 150, and even more preferably 1
0 to 80 people, particularly preferably 12 to 70 people.

These parameters are H/C, do. If either 2 or Lc deviates from the above range, the overvoltage at the electrode body during charging and discharging will become large (as a result, gas will be generated from the electrode body and the safety of the battery will be significantly impaired). Not only that, but 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 Mann spectrum analysis using argon ion laser light with a wavelength of 5.145, 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 5.14 for the carbonaceous material mentioned above.
In the spectral intensity curve recorded on the chart when five people performed Raman spectrum analysis using argon ion laser light, the wave number was 1.580 ± 100 cm-
It refers to the value obtained by dividing the integrated value (area intensity) of the spectral intensity within the range of ' by the area intensity within the wave number range of 1.360 ± 100 cm-', and corresponds to a measure of the degree of graphitization of the carbonaceous material. be.

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 interplanar spacing d ++ of the (110) plane in X-ray wide-angle diffraction analysis. twice the distance ao (2d++ol is 2.
38 people to 2.47 people, more preferably 2.39 people to 2
．． 46 people; the crystallite size La in the a-axis direction is preferably 10 Å or more, more preferably 15 to 150 people, particularly preferably 19 to 70 people.

Furthermore, this carbonaceous material preferably has a volume average particle size of 2.
00P or less, more preferably 0.5F or more 150F+
Particularly preferably particles have a particle size of 2F or more and 100P or less, most preferably 5F or more and 60P or less.

Furthermore, this carbonaceous material has pores inside, and the total pore volume is preferably 1.5 x 10-"i/g or more. More preferably, the total pore volume is 2. Ox
10-”wrl/g or more, more preferably 3, Ox
l O-”ml/g or more 8x l O-2ynl/
g or less, particularly preferably 4. OX 10-3yd/g
It is above 3xlO-''i/g.

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

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 (■, .), the amount of liquid nitrogen filled in the pores (vzql
The total pore volume is determined by converting to .

Here, P and T are the atmospheric pressure (kg/cm") and temperature (K), respectively, and A is the molecular volume of the adsorbed gas (34 for nitrogen, 7 cm3/mo
b).

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 (γP) 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 (γF) is calculated from the equation (1) above.
1° and the BET specific surface area S using the following equation (2).

2V, q γp = , (2) Here, it is assumed that the pore is cylindrical.

The above-mentioned carbonaceous material can be obtained by heating and decomposing an organic compound at a temperature of 300 to 3,000° C. and carbonizing it, usually under an inert gas flow.

Examples of starting organic compounds include cellulose;
Phenol resin; Acrylic resin such as polyacrylonitrile, poly(α-halogenated acrylonitrile); Halogenated vinyl resin such as polyvinyl chloride, polyvinylidene chloride, chlorinated polyvinyl chloride; Polyamide-imide resin; Polyamide resin: polyacetylene, poly Arbitrary organic polymer compounds such as conjugated resins such as (p-phenylene); monomers with three or more membered rings such as naphthalene, phenanthrene, anthracene, triphenylene, pyrene, chrysene, naphthacene, bicene, perylene, penxene, and penxene. A fused cyclic hydrocarbon compound formed by condensing two or more ring hydrocarbon compounds with each other; or a derivative of the above compound such as a carboxylic acid, carboxylic acid anhydride, or carboxylic acid imide; a mixture of the above compounds as the main component Various pitches: At least two or more 3-membered or more-membered monocyclic compounds such as indole, isoindole, quinoline, inquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine, and phenanthrene are bonded to each other, or one A fused heterocyclic compound formed by bonding with the above monocyclic hydrocarbon compound having 3 or more members: Derivatives such as carboxylic acid, carboxylic acid anhydride, and carboxylic acid imide of each of the above compounds: Furthermore, benzene or its carboxylic acid, carboxylic acid, etc. Mention may be made of derivatives such as acid anhydrides and carboxylic acid imides, such as 1.2.4.5-tetracarboxylic acid, its dianhydrides, or its diimides.

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 electrode body of the present invention is a granular material in which a polymer elastomer (synthetic rubber, thermoplastic elastomer, or soft resin in the present invention) is attached to the surface of the carbonaceous material particles described above. , and particles of a metal or an alloy of the active material that can form an alloy with the active material.

Synthetic rubbers that adhere to the surface of carbonaceous material particles include styrene-butadiene rubber (SBR), isoprene rubber,
Examples include butadiene rubber, ethylene-propylene rubber, and butyl rubber.

SDRs include those manufactured by emulsion polymerization and those manufactured by solution polymerization, and both can be used in the present invention.

In SBR by emulsion polymerization, styrene and butadiene are emulsified and randomly copolymerized using water as a dispersion medium. Potassium persulfate or a redox initiator is used as the polymerization initiator, and it is thought that the polymerization proceeds in the form of radical polymerization. Organic peroxides are used as oxidizing agents in redox initiators.
As the reducing agent, divalent iron, tetraethylenepentamine, etc. are used. The content of styrene units in this SBR is 1 to 70 mol%, preferably 1.8 to 50 mol%, more preferably 10 to 30 mol%, particularly preferably 1.
It is 2 to 20 mol%. In addition, there are 1.2 bonds, 1.4 bonds (cis), and 1.4 bonds (trans) in the bonds of butadiene units, but usually 1.2 bonds are 8 to 25 mol%, 1
．． The content of 4 bonds (trans) is 50 to 85 mol%, and the content of 1 and 4 bonds (cis) is 8 to 25 mol%. More preferably, 1
．． 12-18 mol% of 2 bonds, 1,4 bonds (trans)
is 60-75 mol%, 1.4 bond (cis) is 10-20
It is mole%.

Further, SBR obtained by emulsion polymerization has a number average molecular weight of preferably 10.000 to 500.000, more preferably 20.000 to 400.000, and still more preferably 30.000 to 500.000.
．． 000 to 300.000.

SBR by solution polymerization is produced using an organolithium catalyst in an organic solvent such as a hydrocarbon solution. Sometimes bulk polymerization methods can also be used. The content of styrene units in this SBR is 1 to 70 mol%, preferably 1.8 to 5
It is 0 mol%, more preferably 10 to 45 mol%, particularly preferably 15 to 40 mol%. The butadiene unit bond is preferably 8 to 50 mol% of 1.2 bond,
The content of 1.4 bonds (trans) is 30 to 80 mol%, and the content of 1.4 bonds (cis) is 8 to 50 mol%. More preferably 1
．． 10 to 46 mol% of 2 bonds, 1.4 bonds (trans)
is 40 to 70 mol%, 1.4 bond (cis) is 10 to 40
It is mole%.

Inbrene rubber is produced by solution polymerization of isoprene using a Ziegler catalyst or an alkyl lithium as a catalyst.

The bond of isoprene unit is 90 mol% of cis 1.4 bond.
It is preferably at least 91 mol%, more preferably at least 91 mol%, and usually from 91 to 99 mol%.

The number average molecular weight of the isoprene rubber is preferably 5Q, 0
00 to 5.000.000, more preferably 70.0
00 to 3.000.000, particularly preferably so, o
oo~2,500.000.

Butadiene rubber is divided into high cis-butadiene rubber and low cis-butadiene rubber depending on the distribution of bonds of butadiene units.

High cis-butadiene rubber is produced by solution polymerization of butadiene using a Ziegler catalyst such as a Tl-based, Co-based, or Ni-based catalyst. Regarding the bonding of butadiene units, 1.4 bonds (cis) account for 80 mol% or more, preferably 90 mol% or more, more preferably 92 mol% or more, and usually 92 to
98 mol% is used.

The number average molecular weight of the high cis-butadiene rubber is preferably 30.000 to 1.000.000, more preferably 40.000 to soo, ooo, particularly preferably 50.000 to 600.000.

Further, low cis-butadiene rubber is produced by solution polymerization using a lithium-based catalyst. The bond of butadiene units is
Preferably 1.4 bonds (cis) are 20 to 50 mol%, 1
．． 4 bonds (trans) are 40 to 70 mol%, 1.2 bonds (trans) are 5 to 20 mol%, and more preferably 1.4 bonds (cis) are 30 to 40 mol%, 1.4 bonds ( trans) is 50 to 60 mol%, and 1.2 bonds (trans) are 8 to 11 mol%.

The number average molecular weight of low cis-butadiene rubber is 30.000
~200.000 is preferred, and 40.000~100.000.
000 is more preferable, and 50.000 to 70.000
is particularly preferred.

Ethylene-propylene rubber (EPR) is a random copolymer of ethylene and propylene produced by solution polymerization of ethylene and propylene using a Ziegler catalyst. ) It can also contain a diene component (ethylidene norbornene, dicyclopentadiene, etc.).

The ethylene content in EPR is preferably 20-80 mol%
, more preferably 30 to 75 mol%, particularly preferably 40 to 70 mol%.

Butyl rubber is obtained by random copolymerization of imbutylene and a small amount of isoprene using a cationic polymerization catalyst.

The content of isobutylene units in this copolymer is 95 mol%
The above is preferable. The content of isoprene in the copolymer is preferably 0.3 to 3 mol%, more preferably 0.6 to 25 mol%.

The number average molecular weight of butyl rubber is 200.000 to 700.
000 is preferred, 300.000 to 600.000 is more preferred, and 350.000 to 500.000 is particularly preferred.

In addition, examples of the thermoplastic elastomer that adheres to the surface of the carbonaceous material include styrene-butadiene-styrene block copolymer (SBS), styrene-isobrene-styrene block copolymer (SIS), and styrene-butadiene block copolymer (SBS). Polymer (SB), styrene-isoprene block copolymer (SI), styrene-ethylene-butylene-styrene block copolymer (SEBS) obtained by hydrogenating these, styrene-ethylene-
Propylene-styrene block copolymer (SEPS),
Styrene-ethylene-propylene block copolymer (S
Styrenic thermoplastic elastomers such as EP) and syndiotactic 1,2-polybutadiene.

A styrene thermoplastic elastomer is a thermoplastic elastomer that has a polystyrene portion as a resin component and a polybutadiene portion, a polyisoprene portion, an ethylene-butylene portion, and an ethylene-propylene portion as rubber components.

The content of styrene units in the above-mentioned styrenic thermoplastic elastomer is preferably 7% by weight or more and 60% by weight or less,
More preferably, it is 10% by weight or more and 50% by weight or less.

Further, the number average molecular weight of the above-mentioned styrenic thermoplastic elastomer is preferably 2.000 or more and 500,000 or less, more preferably 5.000 or more and 300,000 or less, and particularly preferably 7.000 or more and 200,000 or less. be.

Further, syndiotactic 1,2-polybutadiene is synthesized from butadiene by solution polymerization using, for example, a cobalt-based Ziegler type catalyst.

The 1.2-bond is preferably 80% or more, more preferably 90% or more, and the crystallinity is preferably 10 to 40%.

In addition, examples of the soft resin that adheres to the surface of the carbonaceous material include ethylene-vinyl acetate random copolymer, ethylene-α-olefin random copolymer having 3 to 12 carbon atoms,
A propylene-C2-C4-C12 a-olefin random copolymer may be mentioned.

Ethylene-vinyl acetate copolymer is obtained by radical copolymerization of ethylene and vinyl acetate at high temperature and pressure. Preferably vinyl acetate unit strength is 5% by weight or more and 40% by weight or less,
More preferably, it is 10% by weight or more and 35% by weight or less.

The copolymer of ethylene and α-olefin having 3 to 12 carbon atoms is obtained by copolymerizing ethylene and α-olefin having 3 to 12 carbon atoms using a Ziegler type catalyst. - As the olefin, propylene, butene, and hexene are preferably used, and the content of α-olefin units having 3 to 12 carbon atoms in the copolymer is preferably 5
The content is at least 7% by weight and at most 30% by weight, more preferably at least 7% by weight and at most 30% by weight.

Copolymers of propylene and ethylene or α-olefins having 4 to 12 carbon atoms are also obtained by copolymerizing propylene and ethylene or α-olefins having 4 to 12 carbon atoms using a Ziegler type catalyst. The α-olefin is preferably butene, hexene, etc. The content of ethylene units or α-olefin units having 4 to 12 carbon atoms in the copolymer is preferably 5% by weight or more and 40% by weight or less, more preferably 7% by weight or more. It is at least 30% by weight.

The above-mentioned polymer elastomer is usually dissolved in an organic solvent without crosslinking treatment, and a solution of this polymer elastomer is attached to the surface of the particles of the carbonaceous material described above, and the solvent is evaporated to form the carbonaceous material. A polymer elastomer is attached to the surface of the particles.

There are the following forms in which the above-mentioned polymer elastomer is attached to the surface of the above-mentioned carbonaceous material particles.

■A form in which the surface of the carbonaceous material particles is entirely coated with a polymer elastomer in the form of a thin film (thinness is preferably 1/3 or less of the average diameter of the carbonaceous material particles, more preferably 115 or less, 1/10 The following thinness is more preferable), (1) The surface of the carbonaceous material particles is coated with a polymer elastomer in the form of a thin film as in (2) (not over the entire surface of the carbonaceous material particles, but preferably over a surface area of 415 or less). , more preferably a form in which the entire surface of the carbonaceous material particles is coated with a polymer elastomer over an area of 315 or less); /2 or less, more preferably 1/3 or less, particularly preferably 115 or less in diameter, in which the polymer elastomer is attached in the form of particles; The diameter is preferably 1/3 or less, more preferably 11
A form in which a fibrous polymer elastomer with a diameter of 5 or less, particularly 1/8 or less is attached.

In any case, the surface of the carbonaceous material particles is preferably 415 or less, more preferably 315 or less, particularly preferably 1150 or less, than the case where the entire surface of the carbonaceous material particles is coated with a polymer elastomer. A form coated with a polymer elastomer over 1/2 or more, most preferably 1/20 or more and 215 or less, is suitable from the viewpoint of improving electrode performance.

As a method for coating the surface of the carbonaceous material particles with a polymer elastomer, for example, the following method can be used.

The above-mentioned polymer elastomer is dissolved in an organic solvent such as toluene or benzene under heating or at room temperature, and the above-mentioned carbonaceous material particles are mixed with this solution, and then the solvent is evaporated to form carbonaceous material particles. A polymeric elastomer can be attached to the surface of the elastomer.

Alternatively, the solution of the polymeric elastomer mentioned above is blown out from a nozzle, and the particles of the carbonaceous material mentioned above are dispersed and supplied in the same space, so that the solution in which the polymer component is dissolved adheres to the surface of the particles of the carbonaceous material, and the hot air stream A rubber component or the like can also be attached to the surface of the carbonaceous material particles by evaporating the solvent.

In addition, the carbonaceous material particles are dispersed and brought into contact with the solution containing the polymeric elastomer that is flowing through the nozzle pipe wall, and then the solvent is dried under hot air to form the carbonaceous material particles. Polymeric elastomers can also be attached to the surface.

The amount of the polymer elastomer attached to the surface of the carbonaceous material particles is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, based on 100 parts by weight of the carbonaceous material particles.
More preferably 0.1 parts by weight or more and 15 parts by weight or less, particularly preferably 05 parts by weight or more and 10 parts by weight or less, and most preferably 1 part by weight or more and 7 parts by weight or less.

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 expressed as L i x M (where X is the molar ratio to the metal M). Other metals used as M include, for example, 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 Af2, pb, In, Bi and Cd, more preferably A di , Pb, and In, particularly preferably 8! It is.

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

In L 1x M, X preferably satisfies 0<x≦9, more preferably 01≦X≦5, still more preferably 05≦X≦3, particularly preferably 07≦
X≦2.

As the active material alloy (LixM), 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 gold J):M can be used.

The proportion of the metal (M) or alloy of the active material (LixM) that can form an alloy with the active material in the carrier is:
It is preferably 60% by weight or less, more preferably 5% by weight or more and 50% by weight or less, even more preferably 7% by weight or more and 40% by weight or less.
It is not more than 10% by weight and preferably not more than 30% by weight.

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

A mixture of particles of the above-mentioned carbonaceous material with a polymer elastomer attached to the surface and particles of a metal or an alloy of an active material that can form an alloy with an active material can be prepared by mechanical mixing, etc. It can be prepared.

The secondary battery electrode of the present invention can be molded as follows.

For example, a mixture of particles of the above-mentioned carbonaceous material with an elastic body attached to the surface and particles of a metal (M) that can be alloyed with an active material or an alloy (L x M) containing the active material is prepared. Then, compression molding is performed to form an electrode in an arbitrary shape such as a sheet or a film.

The compression molding temperature is preferably from room temperature to 150°C. The compression molding pressure is preferably 1 kg/cm" to 200,000 kg/cm", more preferably 5
kg/Cm2 to 100.000 kg/cm”.

The compression molding time is preferably 0.1 seconds to 30 minutes, more preferably 0.3 seconds to 10 minutes, even more preferably 0.
．． The duration is from 5 seconds to 5 minutes.

The secondary battery electrode of the present invention further includes a metal net or thin film (foil) made of nickel or the like as a core material, and granules in which a polymer elastomer is attached to the surface of the carbonaceous material particles mentioned above, an active material and an alloy. Possible metals (M) or alloys (LiXM
) by compression molding the mixture with the particles, a good balance between flexibility and strength can be maintained.

That is, particles of a metal (M) or alloy (L 1x M) that can be alloyed with an active material are mixed into a viscous mixed slurry of particles of a carbonaceous material and a solution in which a polymeric elastomer is dissolved. A thin sheet-shaped electrode can be formed by applying it to a metal mesh or foil, drying the solvent, and then compression molding it.

Methods for supporting the active material on the support include chemical methods, electrochemical methods, physical methods, etc. For example, the support may be placed in an electrolytic solution containing a predetermined concentration of alkali metal cations, preferably Li ions. A method of electrolytic impregnation using lithium as a counter electrode and using this support as an anode, 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 bonded to a molded body of a carrier 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
．． 15 parts by weight or less, preferably 0.075 parts by weight or more and 0.12 parts by weight or less, most preferably o, os.

It is not less than 0.100 parts by weight and not more than 0.100 parts by weight.

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 faced to each other with a separator (3) interposed in between and are rolled into a spiral shape, and this is stored in a cylindrical can. It can be a cylindrical secondary battery.

The positive electrode body is not particularly limited, but is preferably made of a metal chalcogen compound that releases or acquires alkali metal cations such as Li ions during charging and discharging reactions. Examples of such metal chalcogen compounds include vanadium oxide. vanadium sulfides, molybdenum oxides, molybdenum sulfides, manganese oxides, chromium oxides, titanium oxides, titanium sulfides, and their composite oxides and composite sulfides. . Preferably, Crs Os , Vz Ox, V, O, , VO
z, Crz Os, Mn0g, Tie,, M OV
z Oa, T i S a, V * S s, Mo
Ss, MOSl, VSg, Cro, 1s
Vo, ysSz, Cro, s Vo, s St, etc. In addition, oxides such as L i C0Ox and WOs, C
uS, F e o, zsV O,? IS x, N a
o, r Sulfides such as Cr S x, N i P S
s, F e P S s, etc., phosphorous compounds, V
Selenium compounds such as S e 2 and N b S e 1 can also be used.

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

The separator that holds the electrolyte is made of a material with excellent liquid retention properties, such as a nonwoven fabric made of polyolefin resin. This separator contains propylene carbonate,
L i C1204, Li C1204, Li C1204, Li C1204, L i
BF4.

It is impregnated with a non-aqueous electrolyte solution of a predetermined concentration in which an electrolyte such as LIAsFs or LIPFs is dissolved.

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

(Function) In the secondary battery configured in this way, active material ions are supported on the carrier during charging in the negative electrode, and active material ions in the carrier are released during 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.

Due to such a combination of electrode reactions of the positive electrode body and the negative electrode body, battery reaction progresses as the battery is charged and discharged.

(Effects of the Invention) The secondary battery electrode of the present invention includes particles of a polymeric elastomer attached to the surface of the particles of the carbonaceous material described above, and particles of a metal or an alloy of an active material that can form an alloy with the active material. By supporting an alkali metal, preferably lithium, on the carrier, it can be formed into a flexible sheet-like electrode, which can then be spirally shaped and applied to a cylindrical secondary battery. be able to. It can also be applied as an electrode for thin sheet batteries or square batteries. Therefore, it is an object of the present invention to provide 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" Samples were dried under reduced pressure at 120° C. for about 15 hours, 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.
2 From the weight of the gas, we can calculate the carbon content, and also calculate the generated H, O
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 of (002) plane (do. 2) and (11)
0) Interplanar spacing (a,, O) If the carbonaceous material is in powder form, it is used as is, or if it is in the form of minute pieces, it is powdered in an agate mortar, and the amount of high purity for X-ray standards is approximately 15% by weight based on the sample. Add silicon powder as an internal standard substance, mix it, fill it in a sample cell, use a graphite monochromator as a monochromatic CuKa line as the radiation source, and measure the wide-angle X-ray diffraction curve using the reflection diffractometer method. Correction of the 0 curve. In this case, the following simple method is used without making corrections for so-called Lorentz factors, deflection factors, absorption factors, atomic scattering factors, etc. That is, by drawing the baseline of the curve corresponding to (002) and (110) diffraction, and plotting the real intensity from the baseline again, we can obtain the (002) plane and (
i io) Obtain a correction curve for the 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. The wavelength λ of the CuKa line is
d by the following Bragg equation. . 2 and d++
. seek.

Yeah λ: 1.5418 people θ, θ': d0゜2, d + +. 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 β ・ cos θ′ There are various discussions about the shape factor K, but K=0.90
was used. Well, θ and θ' have the same meaning 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 and heated to 1.000° C. at a heating rate of 250° C./hour under nitrogen gas flow. , and further held at 1.000°C for 1 hour.

Thereafter, the obtained carbonaceous material particles were set in another electric furnace and heated to 1.800°C at a heating rate of 1.000°C/hour under nitrogen gas flow, and further 1. It was held at 800°C for 1 hour.

The carbonaceous material thus obtained was placed in a 500-mm agate container, and two agate balls with a diameter of 30 mm and a diameter of 25 m were placed.
6 agate balls with a diameter of 20 mm and 16 agate poles 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, xmm wide-angle analysis, and measurement of particle size distribution, specific surface area, etc.

Hydrogen/carbon (atomic ratio) = 0.04 do. 2=3.59 people, Lc=14 people ao(2a++o)=2.4i, La=25 people Volume average particle size=35. BP Specific surface area (BET) = 8.2 m''/g (2) Adhesion of polymer elastomer to the surface of the carbonaceous material particles Nisshin Engineering Co., Ltd. SBR was attached using a barcode. That is, particles of carbonaceous material were supplied and dispersed into the coating nozzle (12) from the screw feeder (11).

3 parts by weight of SBR (manufactured by Japan Synthetic Rubber ■, JSR5L556, styrene content 24%, 1,2-butadiene bond amount 39%) was placed in a dissolving tank (13), and 97 parts by weight of toluene was added to completely dissolve it. This was sent to 11 by the liquid feed pump (14) and brought into contact with the surface of the carbon material together with the air sent out by the compressor (15). This mixture was sprayed from 11 into the drying chamber (16). As a result, the toluene solution in which SBH was dissolved adhered to the surface of the carbonaceous material.

Toluene was removed by sending a stream of hot air heated by the heater (17) into the cyclone (16), and granules with 5% by weight of SBR attached to the surface of the carbonaceous particles were obtained at the bottom of the cyclone (18).

The rubber-adhering particulate matter was carried away by the airflow from 18, but was collected by the filter (19), and the hot air containing toluene was removed from the system via the blower (20).

(3) Mixing of carbonaceous material particles to which polymer elastomer is attached and aluminum particles 70% by weight of carbonaceous material particles to which the above-mentioned SBR is attached and 30% by weight of aluminum particles having a volume average particle diameter of 30F are mixed in a machine. mixed.

(4) Forming a sheet electrode Using a 100-mesh nickel wire mesh as a core material, a mixture of the above-mentioned carbonaceous particles with SBR adhered to their surfaces and aluminum particles was heated at a temperature of 110°C with lO
Compression molding was performed at a pressure of 0.4 kg/cm'' to form a sheet-like electrode of approximately 0.4 mm.

This sheet-like electrode was flexible and had bending strength.

(5) Supporting lithium on the above support Using the above support as one electrode and lithium metal as a counter electrode, electrolytic treatment is performed in a propylene carbonate solution of 1 mol/flood Li CJ204 to form an active material. A negative electrode body was manufactured by supporting lithium. The electrolytic treatment conditions are
Bath temperature 20°C, current density 0,7 mA/cm2,
Lithium equivalent to 800 mAh was supported on the negative electrode body.

(6) Production of positive electrode body MnOz powder Log calcined at 470°C and 1 g of powdered polytetrafluoroethylene were kneaded, and the resulting mixed material was roll-formed to form a sheet with a thickness of 0.4 mm. .

(7) Battery assembly A sheet-like electrode in which lithium is supported on a carrier made of a mixture of SBR particles and aluminum particles on the surface of the above-mentioned carbonaceous material is used as a negative electrode, and a nonwoven fabric made of polypropylene is used as a separator. A sheet-like electrode made of the above-mentioned Mn0z was laminated as a positive electrode, and this was rolled into a spiral shape as shown in FIG. 1 and housed in a stainless steel cylindrical can.

In the separator, 1 mol of Li Cff0/°C-
A battery cell as shown in FIG. 1 was assembled by impregnating it with a propylene carbonate solution and sealing the battery cell.

(8) Characteristics of Li battery The battery manufactured in this manner has a battery voltage of 1.5 mA at a constant current of 20 mA. The battery was discharged until it reached OV. Then, charge with a constant current of 20 mA until the battery voltage reaches 3.3 V, then the upper limit is 3.3 V and the lower limit is 1.8 V (7)
Preliminary charging and discharging was performed for 5 cycles at a constant current of 20 mA with potential regulation.

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 7th 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, it hardly changed in Example 1 compared to the 7th cycle.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the structure of a battery of Example 1. 1... Positive electrode body 2... Negative electrode body 3... Separator (contains electrolyte) Figure 2 is a device for attaching a polymer elastomer to the surface of carbonaceous material particles. FIG. 11... Screw feeder 12...
・Coating nozzle 13...Dissolution tank 14...Liquid pump 15...Compressor 16...Drying chamber 17...Heater 18... ... Cyclone 19 ... Filter 20 ... Blower procedure amendment September 27, 2007

Claims (1)

[Scope of 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 180 Å or less, and the particles have a polymer elastomer attached to the surface of the carbonaceous material particles, and (2) the active material and the alloy. 1. A secondary battery electrode characterized in that a carrier is formed of particles of an alloy containing a metal or an active material that can be formed, and an alkali metal is supported as an active material on the carrier.