JPH08124558A - Carbonaceous electrode plate for non-aqueous electrolyte secondary battery and secondary battery - Google Patents

Abstract

(57) [Summary] [Structure] A carbonaceous matrix is divided into minute blocks, and a flexible carbonaceous molded product having a structure in which carbon fibers penetrate between a plurality of blocks is formed. The present invention relates to an electrode plate and a non-aqueous electrolyte secondary battery using the same as a negative electrode. [Effect] Since the electrode plate using the molded body can be bent into an arbitrary shape, a battery can be configured by a simpler method than the conventional method in which a plurality of electrodes are arranged in parallel or in series, and a cylindrical shape It is effective for forming a prismatic lithium secondary battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode plate for a non-aqueous electrolyte secondary battery using a carbonaceous molded body, and a non-aqueous electrolyte secondary battery using the same. More specifically, the present invention relates to a carbonaceous molded body useful as an electrode plate of a lithium secondary battery, which is a non-aqueous electrolyte secondary battery, and a secondary battery using the same as an electrode.

Since the carbonaceous molded body used as an electrode plate in the secondary battery of the present invention has a characteristic property of being excellent in flexibility, it is extremely useful particularly as a negative electrode of a lithium secondary battery. .

[0003]

2. Description of the Related Art In recent years, downsizing of various electric products,
With so-called miniaturization, there is an increasing demand for miniaturization and high energy density of the battery as the power source. Also, due to the growing interest in environmental protection worldwide, switching to various secondary batteries is also spreading. Among them, the lithium secondary battery using metallic lithium as the negative electrode active material has advantages such as high energy density, small size and light weight, and long-term storability, but the charge / discharge cycle is short and the charge / discharge efficiency in charge / discharge is high. However, the use of metallic lithium poses a risk in the event of trouble, which is a problem from the viewpoint of safety.

The above-mentioned drawbacks are caused by the deterioration of the negative electrode due to an electrochemical reaction in which metallic lithium is deposited on the negative electrode by charging and discharging, and the safety and deterioration during use of the metallic lithium negative electrode cannot be avoided at present. Absent. The use of various carbon materials for the negative electrode has been investigated as a method for solving such a drawback, and until now, for example, a polymer fired body having a conjugated system (Japanese Patent Laid-Open No. 58-093176) and an arylacetylene polymer have been used. Decomposition product (JP-A-59-154763),
Organic material fired product (JP-A-60-235372, JP-A-62-09086)
3), a carbon material having a pseudo-graphite structure (JP-A-62-12206)
6), a carbon fiber molded body (JP-A-62-268056), or a structure having a planar net-like six-membered ring structure (JP-A-63-013282)
A method using a carbonaceous electrode composed of the above is proposed.

The method of using the negative electrode of a lithium secondary battery as a carbon material utilizes an electrochemical reversible adsorption-desorption reaction in which lithium, which is a negative electrode active material, is inserted into and discharged from the carbon material during charge and discharge. is there.

Since the carbon material used as the negative electrode of the lithium secondary battery is generally powdery, when it is used as the negative electrode, it is molded into a predetermined shape by a method such as compression molding using an organic binder. Usually, polytetrafluoroethylene, as a binder for molding carbon materials,
A high molecular compound such as polyethylene or polypropylene is used, which is uniformly mixed with carbon powder and then molded by a pressure molding method, a roll molding method or the like. There is also known a method of applying a mixed liquid obtained by dispersing a carbon material and a binder in a solvent onto a metal current collector such as nickel.

The electrodes formed by these methods contain polytetrafluoroethylene added as a binder, polymer compounds such as polyethylene and polypropylene, and / or a small amount of a solvent, and are therefore characteristic of carbon materials. There is a problem such as a decrease in electric conductivity, and further, it may cause an undesirable phenomenon such as a decrease in discharge capacity due to an increase in overvoltage, heat generation, and a decrease in life. As a method for solving these problems, a method of using an electrode, which has been composed of a carbon powder and a carbonaceous binder, as a negative electrode of a lithium secondary battery (Japanese Patent Laid-Open No. 5-101818), or a method of using a film carbon material. (JP-A-5-242880), a method using a composite sheet of carbon powder and carbon fibers (JP-A-5-283061),
A method (Japanese Patent Laid-Open No. 5-299090) in which a polymer compound having a self-burning property is used by molding and firing has been proposed.

Generally, when a carbonaceous molded body for an electrode composed of carbon fiber and a carbonaceous binder is used, since it has high density and rigidity, for example, a very thin carbonaceous molded body sheet has a predetermined circular shape, Alternatively, even if it is attempted to wind it around a rectangular shape, it breaks brittlely and cannot be wound uniformly. Therefore, when these carbonaceous compacts are used as electrodes, usually the carbonaceous compacts are processed to have a predetermined size and a current collector is attached to each sheet to form an electrode, and the electrodes and the separator film are alternately alternated a plurality of times. A battery is constructed by stacking them.

[0009]

As described above, when the conventional carbonaceous molded body is used, the cut electrode sheet, the separator and the current collector must be laminated to form a battery because of its high rigidity. I have to. In this case, if there is a difference in performance between the electrodes, it is known that overcharging and overdischarging are likely to occur at the time of charging / discharging, the battery performance is degraded, and further, a very dangerous state such as rupture is likely to occur. In other words, instead of the conventional method of forming a negative electrode of a battery by using a large number of electrode plates, it is possible to form a negative electrode with a small number of electrodes, and various types of batteries can be used for high energy density and miniaturization. There was a need for a carbonaceous molded body as an electrode capable of forming various shapes.

[0010]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. The present invention relates to an electrode plate made of a carbonaceous molded article having excellent flexibility and a secondary battery using the same as an electrode, particularly a lithium secondary battery.

The evaluation (definition) of the flexibility of the carbonaceous compact described in the present invention is carried out by contacting a cylinder having a diameter d as shown in FIG. while the evaluating the diameter of the smallest circle when turning without destroying (d _0), defining the diameter (d ₀₎ and the flexible minimum diameter to be evaluated for flexibility. That is, the smaller d ₀ means the better flexibility. Also, this flexibility (d ₀ )
Has a bulk density and thickness dependency. Generally, the smaller the bulk density and the smaller the thickness, the greater the flexibility (d ₀ becomes smaller).

As the flexibility in the present invention, the flexibility obtained at the same bulk density and the same thickness is comparatively evaluated in consideration of the influence of the bulk density and the thickness. It is characterized in that it is 1/10 or less, preferably 1/50 or less of d ₀ of the quality molded product. Here, the carbonaceous molded plate obtained by the usual method means 800 to 1300 ° C.
A commercially available carbon fiber calcined in step 1 is used as a raw material to impregnate and mold a matrix resin to obtain a compact, which is then calcined at 800 ° C. or higher in a vacuum or an inert gas atmosphere to indicate a carbonaceous compact. An example of the difference in flexibility according to the present invention is shown in FIG. 2 in comparison with a carbonaceous molded body produced by a conventional method.

In the flexible carbonaceous molded article according to the present invention, the carbonaceous matrix is divided into minute blocks, a plurality of carbon fibers penetrate between the blocks, and the carbon fibers that penetrate the carbonaceous matrix. It is preferable that the interface between the carbonaceous matrix and the carbonaceous matrix is separated at a certain ratio or more. Such a carbonaceous compact is illustrated in FIG. 3 as a structural schematic diagram. Here, as the size of the minute block of the carbonaceous matrix, the size of one side is 20 μm to 2000 μm.
Each block does not necessarily have to have a uniform size of about m.

The carbonaceous molding having such a structure is charcoal.
So-called C / C consisting of elemental fiber and carbonaceous matrix
(Carbon / carbon fiber) composite
Nevertheless, bending deformation along a curved surface is possible. Or
Carbon fiber and carbonaceous matri are used to express the flexibility.
The binding force of the probe is weak, and it is observed with a scanning electron microscope, for example.
The ratio of the peeled interface between the two is at least 50
% Or more is preferable. In this case at the interface
The carbon fiber and carbonaceous matrix are not firmly fixed
Therefore, there is no slippage between the carbon fiber and the carbonaceous matrix.
What happens and the carbonaceous matrix becomes fine during the firing process
Flexibility is expressed because it is easy to divide into blocks
You. This flexibility is due to the above carbon fiber and carbonaceous matrix
The higher the peeling ratio at the interface with the
In particular, it has excellent flexibility. Such flexibility
As a method to obtain a C / C composite
For example, use carbon fiber with low surface activity as raw carbon fiber.
There is a method of obtaining a molded body. ESCA for low surface activity
(Electron Spectroscopy for Chemical Analisis, X-ray
O of the carbon fiber surface measured by photoelectron spectroscopy)_1S
/ C_1SLower value, contact obtained by dynamic contact angle measurement
Larger antenna, graphitization obtained by X-ray diffraction measurement
A carbon with higher properties is effective, and carbon with these characteristics
Adhesion to carbonaceous matrix when fiber is used as raw material
Since it has little property, it is possible to obtain the above-mentioned flexible carbonaceous molded body after firing.
You can The carbonaceous compact shown in FIG.
_1S/ C _1SAll the same except that carbon fiber with different values is used as the base material
The carbonaceous molded product according to the present invention, which was produced under the conditions
And a comparison of the flexibility of the conventional carbonaceous moldings. This charcoal
The method for producing a molded body is the same as in the examples described below,
Materials are Dona Carbo Paper (trade name, manufactured by Donac),
Trix resin is phenol resin, resin content is 75
%, All molded products after heat curing are baked at 2400 ° C in vacuum
It was made. O from this figure_1S/ C_1SSmall charcoal
Those based on elementary fibers should have excellent flexibility.
Recognize.

In the present invention, the carbon fibers are PAN-based carbon fibers, petroleum-based or coal-based isotropic, pitch-based carbon fibers made of anisotropic pitch as raw materials, rayon-based fibers, and phenol resin fibers by firing. The obtained carbon fiber, vapor-grown carbon fiber obtained by vapor-phase thermal decomposition of benzene, etc. can be used,
There is no particular limitation. Both straight and curved single fibers are used, but curved carbon fibers are more effective in flexibility and straight ones are more effective in tensile strength. .

Here, the curved carbon fiber means a fiber diameter of 0.1 to 0.1.
A straight carbon fiber of 100 μm and an aspect ratio of 50 or more, which has a bent or curved fixed shape capable of elastically deforming in its outer shape, and the specific volume of the random aggregate does not have the bent or curved fixed shape. Which is larger than the specific volume of the random aggregate of. More specifically, for example, the fiber diameter is 13 μm and the aspect ratio is 50 μm.
When the value is 0, the specific volume is 9 cm ³ / g or more. However, the specific volume here is based on the weight of 500 ml of fibers when a random assembly of fibers is filled in a cylindrical container having a diameter of 7 cm under a pressure of 150 g / cm ² .

A typical curved carbon fiber is a short fiber of pitch-based carbon fiber produced by the eddy current blowing method (Japanese Patent Publication No. 58-57374), which is blown out from a plurality of nozzles in a tangential direction of a cone. The molten pitch is blown out from the nozzle by a vortex flow generated by the air flow, is shaped, is curled by the action of the vortex flow, is deposited in the form of a mat as a random aggregate of fibers, and is heat-treated. Such a mat-shaped random aggregate is formed into a felt-like or paper-like sheet by needle punching.

The carbonaceous matrix in the present invention means
Any substance can be used as long as it can be carbonized by firing and integrated with the carbon fiber, for example, thermosetting property of phenol resin, epoxy resin, imide resin, unsaturated polyester resin, melamine resin, urea resin, vinyl ester resin, furfuryl alcohol resin. Resin and a mixture thereof, a residual carbon ratio after firing is relatively high polyphenylene sulfide, polysulfone, a thermoplastic resin such as polyetherimide and a carbonaceous matrix obtained by firing a mixture thereof, further petroleum, coal pitch, Examples thereof include asphalt pitch, coal tar pitch, crude oil cracking pitch, and pitch obtained by thermal decomposition of an organic polymer compound such as a condensed polycyclic hydrocarbon compound or a polycyclic heterocyclic compound.

The ratio of the carbon fiber to the carbonaceous matrix can be within a wide range and is not particularly limited, but it is 1: 9 to 6: 4, more preferably 2: 8 to increase the final density.
A ratio of 4: 6 is used. As a method for molding the flexible carbonaceous molded body before firing, it can be obtained by a conventional method such as thermal compression molding, injection molding, extrusion molding or stampable molding. At this time, for the purpose of increasing density, improving conductivity, etc., other graphite materials such as acetylene black, furnace black, various graphite powders such as natural and artificial graphite, mesocarbon microbeads, carbon fiber milled, etc. are added. You can also do it.

A flexible carbonaceous molded body can be obtained by firing the molded body thus obtained at 800 ° C. or higher in a vacuum or an inert gas atmosphere. 80
If the firing temperature is 0 ° C. or lower, the flexibility is not sufficiently expressed. The specific firing temperature varies depending on the composition of the molded body, but is determined so that the performance as the negative electrode of the secondary battery is optimum.

The obtained flexible carbonaceous molded product is used as a negative electrode of a secondary battery assembled as a battery. That is, the obtained carbonaceous molded article, when containing lithium in the positive electrode active material of the positive electrode, more specifically, as the positive electrode active material, for example, LiCoO ₂ , LiNiCoO ₂ , LiNiO ₂ , LiMnO ₂ , or LiMn ₂ O. _{When 4} is selected, it is used as a negative electrode as it is, while when the positive electrode active material does not contain lithium, the flexible carbonaceous molded body is allowed to store a predetermined amount of lithium in advance, or a predetermined amount of lithium is stored. Used by crimping.
When carrying out the present invention, the method of occluding lithium in the negative electrode flexible carbon molded body is not particularly limited. For example, a carbonaceous molded body is used as a negative electrode in an organic electrolyte, and metallic lithium is used as a positive electrode A method of passing an electric current through it, an electrochemical method such as short-circuiting both electrodes with a conductor, or a laminated body in which carbonaceous compacts are sandwiched or contacted with two metallic lithium plates and immersed in an organic electrolytic solution. Then, a physical method such as contacting with metal lithium or immersing a carbonaceous molded body in a predetermined amount of metal lithium foil or the like and then immersing it in an organic electrolytic solution is possible.

The positive electrode in the secondary battery of the present invention is not particularly limited as long as it has the performance as a secondary battery positive electrode, and any of them can be used. As the separator, synthetic resin fibers such as polyethylene, polypropylene and polytetrafluoroethylene, or woven or non-woven fabric of glass fibers or natural fibers can be used.

[0023] As the non-aqueous electrolyte solution in the present invention a secondary _{battery, LiClO 4, LiBF 4, LiPF} 6, LiAsF 6, a high dielectric constant of the organic lithium salt LiSbF ₆ such at a concentration of 0.1 to 5 mol / l A solution dissolved in a solvent such as acetonitrile, propionitrile, propylene carbonate, ethylene carbonate, tetrahydrofuran, dioxane, diethyl carbonate, dimethyl carbonate, 1.2 dimethoxyethane, dimethyl sulfoxide, etc. is used.

The shape of a secondary battery having a carbonaceous molded body as a negative electrode is usually coin type, paper type, card type, cylindrical type, box type, or the like. In the present invention, carbon used as a negative electrode is used. Since the quality molded body is flexible, the positive electrode, the separator, and the flexible carbonaceous molded body are spirally wound to form a cylindrical battery, or the volumetric efficiency is improved. It is possible to form a secondary battery by changing the shape of the flexible carbonaceous molded body with a certain curvature.

In this specification, the electrode plate of the present invention is mainly described as a negative electrode of a secondary battery.
It can be used as a positive electrode or used in a primary battery as desired.

[0026]

EFFECTS OF THE INVENTION The electrode plate or secondary battery of the present invention has, for example, a large number of plate-like carbonaceous compacts wired in series or in parallel inside the battery and used as a negative electrode. It is possible to use one flexible carbonaceous molded body and a separator together as a negative electrode in a rolled or folded shape, and it is possible to improve the volumetric efficiency as a battery and the performance of each electrode plate. It is possible to avoid a dangerous state such as a decrease in battery performance due to overcharge or overdischarge due to a difference, or a burst.

[0027]

EXAMPLES The effects of the present invention will be described below with reference to examples and comparative examples. These examples are for specifically explaining the present invention, and the technical scope of the present invention is not limited thereto. It is not intended to be limiting.

Example 1 Donacarb S-251 (trade name, manufactured by Donac Co .: 50)
g / m ² paper, fiber diameter 13 μm, aspect ratio 2
Carbon fiber paper (O)
_1S / _C1S = 0.04) is impregnated with phenol resin: Phenolite J-325 (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) as a matrix resin, and the resin content is 80% by weight.
I got a prepreg of. The resin content of the molded product obtained by heat-curing and compression-molding 1 ply of this prepreg is 77% by weight.
Is. The compact was fired at 2400 ° C. in a vacuum atmosphere to obtain a carbonaceous compact having a thickness of 0.12 mm and a density of 1.0 g / cm ³ carbon fiber content of 35% by weight. This molded product is flexible, and has a minimum flexible diameter of 1 mm, and the ratio of carbon fibers with interfacial peeling observed in the cross section of the molded product is 8 mm.
It was 1% (the number of peeling 495 / the total number of inspection 611). A test piece for a negative electrode of a secondary battery having a size of 10 × 30 mm (weight: 63 mg) was punched out from the obtained flexible carbonaceous molded product.

As the positive electrode, a mixture obtained by mixing 85 parts by weight of LiCoO _{2 with} 10 parts by weight of acetylene black and 5 parts by weight of polytetrafluoroethylene powder and compression-molding (weight 14
0 mg, 10 × 30 mm), and an electrolyte solution of lithium perchlorate dissolved in an equal volume mixture of ethylene carbonate and diethyl carbonate (concentration: 1 mo)
1 / l) was prepared and used. Using these positive and negative electrode plate test pieces and the electrolytic solution, a cylindrical secondary battery was formed by stacking a polyethylene microporous film (separator) having a thickness of 34 μm and winding it in a cylindrical shape having a radius of 5 mm. The initial circuit voltage of the secondary battery obtained here was 3.2 V (volt).

[0030] Then after the charging voltage at a current density of 1.0 mA / cm ² was subjected to constant current charging until 4.10 V, was subjected to constant current discharge test at a current density of 1.0 mA / cm ^2, the initial The result was that the discharge capacity was 10.8 mAh and the efficiency of the initial discharge capacity was 92.0%. Then, a constant current discharge cycle test was carried out under the conditions of a current density of 1.0 mA / cm ² , a lower limit voltage of 2.00 V and an upper limit voltage of 4.10 V. The discharge capacity at the 50th cycle was 10.0 mAh, 20
The discharge capacity at the 0th cycle was 9.5 mAh and the discharge capacity at the 500th cycle was 9.3 mAh. When the secondary battery after the 500th cycle constant current charge / discharge test and the test piece were disassembled and disassembled and inspected, no abnormality was found.

Example 2 Instead of the phenol resin used in Example 1, a furfuryl alcohol resin: DA-404 (manufactured by Dainippon Ink and Chemicals, Inc.) was impregnated to obtain a prepreg having a resin content of 79% by weight. It was The resin content of the molded body obtained by heat-curing compression molding of this prepreg 5 ply is 75% by weight, and the molded body is baked at 2400 ° C. in a vacuum atmosphere,
A carbonaceous compact having a thickness of 0.47 mm, a density of 1.2 g / cm ³ and a carbon fiber content of 38% by weight was obtained. This molded body is flexible, and has a minimum flexible diameter of 12 mm.
The ratio of carbon fibers with interfacial peeling observed in the cross section of the molded product was 89% (peeling number 328 / total inspection number 369). A cylindrical secondary battery was constructed from this flexible carbonaceous molded body in the same manner as in Example 1 and tested. The initial circuit voltage of the secondary battery obtained here was 3.2V.

[0032] Then after the charging voltage at a current density of 1.0 mA / cm ² was subjected to constant current charging until 4.10 V, was subjected to constant current discharge test at a current density of 1.0 mA / cm ^2, the initial As a result, the discharge capacity was 15.0 mAh and the efficiency of the initial discharge capacity was 91.2%. Then, a constant current discharge cycle test was carried out under conditions of a current density of 1.0 mA / cm ² , a lower limit voltage of 2.00 V and an upper limit voltage of 4.10 V, and the discharge capacity at the 50th cycle was 14.0 mAh, 20.
The discharge capacity at the 0th cycle was 13.5 mAh, and the discharge capacity at the 500th cycle was 13.3 mAh. 500
When the secondary battery after the constant current charge / discharge test of the cycle and the test piece were similarly disassembled and disassembled and inspected, no abnormality was found.

Example 3 In place of Donacarb S-251 in Example 1, Donacarb S-223 similarly fired in a vacuum atmosphere was used.
(Product name, manufactured by Donac: 300 g / m ² felt,
A prepreg having a resin content of 80% by weight was similarly obtained by impregnation with a fiber diameter of 13 μm and an aspect ratio of 1000 or more). The resin content of the molded product obtained by heat-curing and compression-molding 1 ply of this prepreg was 76% by weight, and the molded product was fired at 2400 ° C. in a vacuum atmosphere to have a thickness of 0.75.
A carbonaceous compact having a carbon fiber content of 36% by weight and a carbon fiber content of 1.1 g / cm ³ was obtained. This molded body has flexibility, the minimum flexible diameter is 22 mm, and the ratio of carbon fibers for interfacial peeling observed in the cross section of the molded body is 85% (peel number 264 / total inspection number 309). Met. A cylindrical secondary battery having a radius of 10 mm was constructed from the flexible carbonaceous molded body in the same manner as in Examples 1 and 2, and a test was conducted. The initial circuit voltage of the secondary battery obtained here was 3.2V.

[0034] Then after the charging voltage at a current density of 1.0 mA / cm ² was subjected to constant current charging until 4.10 V, was subjected to constant current discharge test at a current density of 1.0 mA / cm ^2, the initial As a result, the discharge capacity was 24.2 mAh and the efficiency of the initial discharge capacity was 89.3%. Then, a constant current discharge cycle test was carried out under conditions of a current density of 1.0 mA / cm ² , a lower limit voltage of 2.00 V and an upper limit voltage of 4.10 V. The discharge capacity at the 50th cycle was 22.8 mAh, 20.
The discharge capacity at the 0th cycle was 21.2 mAh and the discharge capacity at the 500th cycle was 20.7 mAh. When the secondary battery after the constant current charge / discharge test at the 500th cycle and the test piece were similarly disassembled and disassembled and inspected, no abnormality was found.

Comparative Example 1 With respect to the carbon fiber paper in Example 1, the O _1S / C _1S value was _maintained at a remarkably large value without firing and the resin was impregnated in the same manner to obtain a prepreg having a resin content of 80% by weight. It was
The resin content of the molded product obtained by heat-curing compression molding of this prepreg 1 ply was 77% by weight, and the molded product was baked at 2400 ° C. in a vacuum atmosphere to have a thickness of 0.12 m.
m, the density was 1.0 g / cm ³ , and the carbon fiber content rate was 35% by weight. This molded product did not have flexibility because the interface between the carbon fiber and the carbonaceous matrix was in close contact. The minimum flexible diameter of this carbon material is 230 mm
And d ₀ is smaller than that of the flexible carbonaceous molded article of Example 1.
It was 50 times or more. Therefore, it cannot be wound into a cylindrical shape and a cylindrical secondary battery cannot be constructed.

Comparative Example 2 Regarding the carbon fiber in Example 1, a carbon fiber mat (O _1S / C _1S = 0. 0) obtained by firing a trading card mat (trade name, mat manufactured by Toray Industries Co., Ltd .: 30 g / m ² mat) in a vacuum atmosphere. 04)
Was prepared in the same manner as above to obtain a prepreg having a resin content of 80% by weight. The resin content of the molded product obtained by heat-curing compression molding of this prepreg 2 ply is 75% by weight,
The molded body was fired at 2400 ° C. in a vacuum atmosphere to have a thickness of 0.16 mm and a density of 1.0 g / cm ³ carbon fiber content #
A # carbonaceous compact was obtained. The ratio of interfacial peeling carbon fibers observed in the cross section of this molded body was 80% (peeling number 36
1 / total inspection number was 451), but the minimum flexible diameter was 75 m
Since it was m, it was not possible to construct a cylindrical battery having a radius of 5 to 10 mm as described in Examples 1 to 3 by using this molded body.

Comparative Example 3 As the negative electrode in Example 1, donacarb S-241 (trade name, manufactured by Donac Co .: carbon fiber milled, fiber diameter 13 μm, aspect ratio 10, O _1S , which was fired in a vacuum atmosphere, was used.
/ C _1S = 0.04) 85 parts by weight and 15 parts by weight of polytetrafluoroethylene powder, and compression molded (thickness 0.30 mm, weight 90 mg, 10 × 30 mm)
A cylindrical secondary battery having a radius of 5 mm was constructed by using and the same charge / discharge test was conducted. The initial circuit voltage of the secondary battery obtained here was 3.1V.

[0038] Then place the charging voltage at a current density of 1.0 mA / cm ² was subjected to constant current discharge test at a current density of 1.0 mA / cm ² After performing constant current charging until 4.10 V, the initial discharge As a result, the capacity was 6.5 mAh and the efficiency of the initial discharge capacity was 90.8%. Then, a constant current discharge cycle test was conducted with a current density of 1.0 mA / cm ² and a lower limit voltage of 2.
00V Upper limit voltage 4.10V
The discharge capacity at the 0th cycle was 4.4 mAh, and the discharge capacity at the 130th cycle was 1.2 mAh. When the secondary battery after the 130th cycle constant current charge / discharge test and the test piece were similarly disassembled and disassembled and inspected, the negative electrode expanded,
Moreover, cracks were present and they did not function as batteries.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a flexibility evaluation method (definition of flexibility).

FIG. 2 is a graph showing a comparative example of the flexibility of the carbonaceous molded body according to the present invention and the carbonaceous molded body according to a known ordinary method.

FIG. 3 is a structural schematic view conceptually showing a flexible carbonaceous molded body of the present invention.

Claims (12)

[Claims] 1. A carbonaceous electrode plate for a non-aqueous electrolyte secondary battery, which is composed of a carbonaceous molded article which is composed of carbon fibers and a carbonaceous matrix and which itself has flexibility. 2. A flexible carbonaceous molded article is composed of a carbonaceous matrix divided into minute blocks and carbon fibers which penetrate a plurality of the minute blocks. 1. The electrode plate according to 1. 3. The electrode plate according to claim 2, wherein the carbonaceous molded body is separated from each other at 50% or more of the interface between the carbon fiber and the carbonaceous matrix. 4. The electrode plate according to claim 3, wherein the carbonaceous molded body is separated from each other at 80% or more of the interface between the carbon fiber and the carbonaceous matrix. 5. The electrode plate according to claim 1, wherein the carbon fibers include curved carbon fibers. 6. The curved carbon fiber has a fiber diameter of 0.1 to 100.
The same kind of straight carbon fiber having a bent or curved fixed shape capable of elastically deforming in its outer shape with a micrometer and an aspect ratio of 50 or more, and the specific volume of the random aggregate does not have the bent or curved fixed shape. The electrode plate according to claim 5, which has a specific volume larger than that of the random assembly of. However,
The specific volume here means a random aggregate of fibers with a diameter of 7c.
m based on the weight of 500 ml of fiber when filled in a cylindrical container under a pressure of 150 g / cm ² . 7. A curved carbon fiber is obtained by depositing short fibers of pitch-based carbon fiber produced by the eddy current blowing method in a mat shape,
The electrode plate according to claim 5, which is obtained by heat treatment. 8. The minimum flexible diameter (d ₀ ) of the flexible carbonaceous molded body is 1/10 or less, preferably 1/50 or less of the value of a normal carbonaceous molded body having the same bulk density and the same thickness. It exists, The electrode plate as described in any one of Claims 1-7 characterized by the above-mentioned. 9. The electrode plate according to any one of claims 1 to 8, wherein the carbon fiber and the carbonaceous matrix in the carbonaceous molded body have a ratio of 1: 9 to 6: 4. 10. A non-aqueous electrolyte secondary battery using, as a negative electrode, a carbonaceous electrode plate composed of a carbonaceous molded body which is composed of carbon fibers and a carbonaceous matrix and which itself has flexibility. 11. A non-aqueous electrolyte secondary battery using the electrode plate according to claim 2 as a negative electrode. 12. The secondary battery according to claim 10, wherein the secondary battery is a lithium secondary battery.