JPS63100009A - Activated carbon - Google Patents

Abstract

PURPOSE:To obtain an activated carbon with high ion adsorbing and desorbing capacity and useful for an electrode of a secondary battery by allowing it to have a specified parameter of graphitical crystal structure at the diffraction peak of face (002) in an X-ray diffraction intensity curve. CONSTITUTION:A fiber such as PVA is stuck with about 10wt% dehydrating agent of the fiber amt. by impregnating with the aq. soln. of the dehydrating agent consisting of (NH4)2SO4, and (NH4)2HPO4, etc. The fiber is dehydrated and carbonized to lose 45-50wt% of the fiber while controlling the shrinkage rate of the fiber, and then is activated at <=1,000 deg.C. The X-ray diffraction intensity curve of the obtained activated carbon fiber with >=500m<2>/g specific surface area is measured and then the sheet-like activated carbon with the parameter Ip/Io of graphitic crystal structure at the diffraction peak of the face (002) of >=0.3 is obtained. [wherein Ip is the largest intensity in the range over the tangent line drawn at the skirts of the diffraction peak of the face (002) and Io is the residual X-ray intensity obtained by reducing the air dispersion intensity from the actually measured diffraction intensity with 2theta diffraction angle indicating Ip.].

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a carbon material having an amorphous structure that greatly increases the amount of stable adsorption of ions to the carbon material in an electrolytic solution. The purpose is to obtain.

[Conventional technology]

Carbon has been actively researched recently because it can absorb many ions. In particular, carbon fibers having a fibrous form are being actively researched because they are easy to handle as electrodes. In order to increase the amount of ions adsorbed to carbon, particularly carbon fiber, studies are being conducted from two main directions. One approach is to electrochemically store various ions between the layers of graphite, which is a layered compound, by increasing the degree of graphitization of carbon fibers (Jikou 6O-36315).

Furthermore, in the other direction, by making the specific surface area of the fibers extremely large in charcoal RJ4 (100r+?/f
The above) is a method that attempts to increase the storage capacity based on the formation of an electric double layer, which is an interfacial phenomenon. By using activated carbon fiber with a large specific surface area, electrician single-layer capacitors (Jikai 58-206116, Jikai 55-99714) or secondary batteries (%A 59-1) have increased storage capacity.
46165, Jikai 6O-25152), and a counter electrode for electrochemical display devices (Japanese Patent Laid-open No. 59-143130).

[Problem that the invention seeks to solve]

As described above, significantly increasing the ion adsorption/desorption ability of carbon materials has been an extremely important industrial issue. However, the amount of ions that can be stably adsorbed and desorbed into the carbon material is only 1 to 4 moles per carbon atom constituting the carbon material. In this case, stable adsorption/desorption means that the ion adsorption/desorption mechanism of Hama Carbon I material is not destroyed due to ion adsorption (including intercalation reaction), and the charge efficiency is at least 80% or more. It means that adsorption and desorption of ions is possible. When comparing a powder or film carbon material with a fibrous carbon material, the t'R fibrous form is particularly excellent as an electrode because it has a large contact area with the electrolyte. When made into a fibrous form, the diameter is approximately 10μ
It is also possible to obtain one of about m.

Among carbon materials, graphite has the most developed crystal structure.

When ions are adsorbed and desorbed onto graphite in an electrolytic solution using an electrochemical method (in this case, an intercalesin reaction), the amount of ions that can be stably adsorbed and desorbed is at most 1 molti per carbon atom of graphite. Therefore, the ion adsorption N'll is 1
If the ion adsorption and desorption mechanism of graphite is destroyed when the temperature is increased to more than 1 mol, the stable ion adsorption amount of graphite was at most 1 mol per carbon atom [Denki Kagaku, 46, Mu 8 (1973) 438 ~441].

The amount of stable ion adsorption of carbon, especially carbon fiber (more than 1 o gt, hereinafter referred to as activated carbon fiber), which has a large specific surface area is, for example, when activated carbon fiber is used on the positive electrode side of a secondary battery, The carbon atom density of carbon fiber was at most 2 to 4 mol[synthetic metal (5ynthet
ic Metalg), 10 (1985) 229-2
34, 26th Battery Debate (1985)! s performance abstract collection 5
7 (IA-15)) 0 The charging and discharging mechanism of activated carbon fa fibers is said to be based on an electric double layer, but it has been pointed out that the part that is charged in a high potential region is based on an intercalation reaction. ing.

Therefore, an object of the present invention is to provide a carbon material capable of stably adsorbing and desorbing ions at a high level. After conducting various studies, it was discovered that carbon materials with an amorphous structure have an extremely high ability to stably adsorb and desorb ions, and it was recognized that the above-mentioned problems could be solved.

X-ray diffraction is the main experimental method used to study the microscopic structure of carbon materials, including carbon fibers, and detailed studies have been carried out not only on graphite and carbon black but also on amorphous carbon. [Carbon materials (Materials science series 3,
Kyoritsu Shuppan), Chapter 4] The height of the X-ray diffraction peak of a carbon material corresponding to the (002) plane of a graphite crystal indicates the degree of crystallinity caused by aromatic condensed rings, and the cattle price width is the Showing size and uniformity. (Katsuniku 1 Journal of the Chemical Society of Japan, 19
75°(9), pp. 1551-1554).

A method for analyzing the structure of carbon using (002) plane diffraction from an actual X-ray diffraction intensity curve (CuKα) will be described. Figure 1 shows the X-ray diffraction of polyacrylonitrile activated carbon fiber (specific surface area 1000i/r). This is an intensity curve. (0
02) A tangent line j was drawn to both sides of the X-ray diffraction peak of the plane, and the difference between the measured curve and the tangent line was rewritten on the baseline to obtain a curved line. Diffraction angle 2 showing the maximum value Ip and IP of the curved line
Further, the intensity Io was determined by subtracting the air scattering intensity from the intensity of the measured curve at the diffraction angle 2θ. The air scattering intensity was obtained by scanning under the same conditions without a sample. Here, Ip is the X-ray diffraction peak intensity due to the graphitic crystalline structure, (io-Ip)F'i
This is the X-ray scattering intensity due to the defective structure.

Generally, the diffraction peak intensity increases as the crystal size and crystallinity of the crystallite increases, indicating the degree of crystal development. The crystal size is determined by the peak sharpness K (X-ray
Diff, Procedures, P537 (19
54)) In the case of many activated carbons or activated carbon fibers, the size of microcrystallite in the direction perpendicular to the (002) plane is 10~
There were 16 people. Crystallinity is generally the ratio of the total crystal scattering intensity to the total scattering intensity, and refers to the volume fraction of crystals in the X-ray irradiation volume [Journal of the Japan Institute of Textile Technology, Vol. 31 (1975)
), pp. 203-214]. However, in the case of carbon materials, the crystalline portion and the amorphous portion are not clearly separated structurally (J, Appl.

PhY, 13 (1942) P364-P371, Basics of carbonization industry (Ohmsha) Chapter 1, Carbon materials (Kyoritsu Shuppan)
Chapter 4], the internal structure cannot simply be understood as a two-phase structure consisting of a crystalline part and an amorphous part, as is the case with ordinary crystalline polymers. In the case of activated carbon or activated carbon fiber, microcrystallites with extremely low degree of perfection are dispersed in an amorphous sea [Chapter 2 of Activated Carbon Industry (Kyoritsu Publishing)], and the crystallites are separated from the graphitic crystalline region of their texture. The coherent scattering is Ip, and the incoherent scattering from the amorphous region is (Io - Ip)
It is.

Ip/I is a parameter used in the present invention.

indicates the degree of development of graphitic crystalline structure.

However, as mentioned above, there is a big difference between the degree of development of the crystalline structure in activated carbon and the so-called degree of crystallinity in the case of ordinary polymer materials. It is not clearly defined structurally. For a fully developed, nearly perfect graphite crystal, the IP/IO is 0.96.
That's all. In addition, all conventionally known activated carbons used as secondary battery materials, including activated carbon fibers, have Ip/I.

is larger than 0.35, but the large T# of the present invention is rumored to be Uraaki#ki activated carbon, especially activated carbon fiber, has an Ip/Io of 0.3 or less and a graphite-like crystalline structure is extremely underdeveloped. It is interpreted that We mainly refer to such activated carbon, especially activated carbon 11M, as activated carbon or activated carbon fiber with a non-structural structure, and Ip/Io as a graphite-like crystalline structure parameter. Furthermore, the activated carbon, particularly the activated carbon fiber, of the present invention basically consists of a phenyl group skeleton, and furthermore, substantially no CH absorption is observed in the infrared absorption spectrum.

The activated carbon of the present invention has a hydrogen to carbon ratio of usually 5 molti or less, preferably 3 molti or less, particularly preferably 2 molti or less.

At the same time as the Ip/Io parameter, the X of the (002) plane!
! The diffraction angle 2θ of (CuKα) is also an important parameter indicating the structure of carbon. The carbon material according to the present invention has Ip/I
o is 0.3 or less, and 20 is 24° or less. The fact that the diffraction angle 2θ is less than 24° means that Bragg's equation 2
This means that the interplanar spacing d of the (002) plane calculated from dsinθ=λ is 3.708 Å or more.

Considering that the perfect graphite crystal has d=3.3543 people [Kagaku Special Edition 87 (1981) P127-136],
It can be said that the carbon material of the present invention has a structure far different from that of graphite. However, as Ip/Io approaches zero, 2θ becomes difficult to measure.l) When Ip/Io is almost zero, it is practically impossible to measure.

FIG. 2 shows an X-ray diffraction intensity curve in the (002) plane of a typical activated carbon fiber of the present invention, and its Ip/I.

11t0.07, there are almost no diffraction peaks due to the crystalline structure, and it can be seen that the structure is extremely inferior.

The present inventors conducted extensive studies on carbon materials suitable for electrodes and found that non-quality carbon materials are superior in terms of electrode performance. That is, it has been found that as the graphitic crystal parameter (Ip/Io) becomes smaller, the electrode performance is significantly improved.

When Ip/Io is 0.8 or less, the specific surface area increases as the rough structure of the activated carbon fiber increases. Activated carbon fiber made from polyacrylonitrile as a starting material has a specific surface area of about 100 On? /r, Ip/Io was 0.66. Additionally, activated carbon fiber made from rayon has a specific surface area of approximately 1500rr! /f, Ip/Io was 0.54. In activated carbon fibers made from phenol, Ip/Io was 0.37 even when the specific surface area was increased to 2300 rt/l. Further, Ip/Io of the powdered carbon material was 0.7 for petroleum coke, 0.6 for carbon black, and 0.5 for charcoal.

Raw materials for activated carbon used in the present invention include natural polymers,
Examples include pitch and organic synthetic polymers.

The organic synthetic polymers include semi-synthetic polymers such as cellulose in addition to synthetic polymers such as polyvinyl alcohol, phenol resin, and polyacrylonitrile. Among these, polyvinyl alcohol is preferably used in order to achieve Ip/Iof: 9.3 or less. The manufacturing method of polyvinyl alcohol is not limited. It may also be treated with a small amount of a modifier.

Examples of raw materials for activated carbon used in the present invention include synthetic organic polymers and pitch. The synthetic organic polymers include pure synthetic polymers such as polyvinyl alcohol, phenolic resin, polyacrylonitrile, etc., as well as semi-synthetic polymers such as fiber-based conductors. Ip/Io is 0.3 or less, particularly preferably 0.2
To achieve the following, the method of constructing the palanquin is not limited. Maf
c. These fibers may be modified with a small amount of a modifier for the purpose of improving their physical properties. In addition, polyvinyl alcohol fibers may be cross-linked for the purpose of improving water resistance.

An example of a method for manufacturing an activated carbon fiber that satisfies the above Ip/Io will be described, but the present invention is not limited to this method.

Generally, the production of activated carbon fibers consists of a dehydration process, a carbonization reaction process, an activation process, a washing process, and a drying process. Ip/Io
In order to reduce this, it is important to select the method of applying the dehydrating agent, the dehydrating conditions, and the activation conditions.

Equal weights of ammonium sulfate and ammonium phosphate as dehydrating agents are applied at a concentration of about 10% by an impregnation method, and the weight loss of the fibers is reduced by 45 to 509% while controlling the shrinkage rate of the fibers.
It would be a good idea to dehydrate and carbonize it to a temperature of about 6°C, and then activate it at a relatively low temperature, for example, 1000°C. At this time, by taking a longer activation time, the yield of activated carbon fibers decreases, but the desired Ip
Activated carbon fibers with a small /Io can be obtained.

"Activity" as used in the present invention means that the specific surface area is large. Generally, the specific surface area measured by the BET method is 100 m'/f or more. The larger the specific surface area, the larger the contact area with the electrolyte, which improves electrode performance. What is the preferred specific surface area?

500rl/or more, more preferably 1000ni',
#that's all.

Special VCFi2000d/f or higher.

The activated carbon fibers may be used as electrodes for batteries or the like as they are, or after being subjected to any known treatment such as a lath or vapor-deposited film of aluminum or titanium, to provide a current collector. As in the past, the activated carbon fibers may be in any shape such as felt, cloth, paper, etc., but sheet-like is best.

Although the present invention has been described above with respect to activated carbon fibers, the activated carbon of the present invention may be in any shape such as powder, sheet, or film.

〔Effect of the invention〕

The present invention proposes that when activated carbon, which mainly has an amorphous structure, is used as an electrode for a secondary battery, the device can be made small, lightweight, and easy to melt, and has a high energy density, so it can be used industrially mainly for power storage purposes. Very important. Furthermore, using fuel cell fibers for solvent recovery, we created a lithium secondary battery in which the negative electrode is lithium metal, the positive electrode is a carbon material, and the electrolyte is an organic non-aqueous solvent, and its performance was investigated. In terms of stability and charge efficiency, when the rate of adsorption and desorption of ions is 97 to 100 mol of carbon atoms, it is possible to charge and discharge at least 200 cycles at an extremely high efficiency. Furthermore, ion adsorption and desorption N
Even when the ratio is increased to 6 mol %, at least 200 cycles of charging and discharging are possible at an efficiency of 95 to 99 cm.

Furthermore, even when the ion adsorption/desorption rate is increased to 12 mol %, at least 100 cycles of charging and discharging are possible at a charge effect of 2 $90 to 80 yen.

As described above, the major features of the secondary battery using the activated carbon of the present invention are high charge efficiency and good cycle stability at a high ion adsorption/desorption rate. Furthermore, this secondary battery has an output density of 10 to 20kw/'9 and a lead secondary battery (1,
Another major feature is that it is extremely large, approximately 10 to 20 times as large as 2kW/Ay).

〔Example〕

The present invention will be described in more detail with reference to Examples below.0 Example 1 [Synthesis of activated carbon fiber mainly having a non-structural structure using polyvinyl alcohol fiber as a starting material] P spun from PVA (polyvinyl alcohol) aqueous solution by wet spinning method
VA fiber (denier 1800d, number of filaments 100
A woven fabric obtained from a fabric with a strength of 10.5 f/d and an elongation of 7% was used. Next, dissolve 5 of each of (NH4)2SO4 and (NH2HPO4) as dehydration and carbonizing agents in 10002 water, heat this aqueous solution to 60°, soak the woven fabric in it for 5 minutes, and then use a mangle. The liquid was squeezed out and dried for 3 minutes at 105° C. The adhesion rate of the dehydrating agent was 10% by weight.

When heating the woven fabric coated with this dehydrating agent at 210°C for 30 minutes, 1 ml of woven fabric! Is it 50? The shrinkage rate of the fiber was controlled to 40% by applying a low tension of . Furthermore, the carbonization condition is 330℃XIO minutes and then 400℃×
Even when heating in two stages for 20 minutes, the width of the woven fabric is 1.
A low tension of 0.09 was applied to give a fiber shrinkage ratio of 60!1 compared to the starting PVA fiber. Furthermore, the weight reduction rate Vi5 at that time
It was 5%. A woven fabric made of black carbonaceous fibers that has been dehydrated and carbonized as described above is placed in a combustion gas at 950°C for 1 hour.
An activated carbon fiber sheet was obtained by performing activation for 0 minutes.

The specific surface area of the BET method using N2 gas was 2300 d/9.

The X-ray diffraction intensity curve of this activated carbon fiber was obtained from Rigaku Denki Co., Ltd.
ItType RAD-
It was measured using rA. Measurement conditions are 40kV100mA
, CuKa line (λ = 1.5418 people), slit width 1/2°, 0.15so++ scanning speed g 1'/min,
7 le scale 8o.

Measured by transmission method at cpa. The graph obtained in this manner is shown in FIG. It was found that the peak based on the (002) plane, which should exist around 2θ of 25°, almost disappeared, and carbon fibers with a non-standard structure were mainly produced (Ip/Io=0 .07). The internal finer structure was examined using solid-state high-resolution NMR. MAS using JEOL Ltd. MGX-270
Be sure to measure using the GATE method. Data points are 8
, sampling point) 1.5, number of scans 100
The results of measurements conducted under the conditions of 00 times are shown in FIG. Since a curve having a peak around 140 PPM was obtained, it was confirmed that the structure was centered on a phenyl group skeleton. The abundance ratio of hydrogen atoms to carbon atoms determined by elemental analysis was less than Fi2 molti. The results of surface reflection infrared are shown in Figure 4, and no C-H absorption was observed, confirming that almost complete carbonization occurred. By changing the fc activation conditions, Ip/Io can be increased from 0.42 to
Several samples were synthesized up to 0.07 (Table 1). Ip/l
In order to reduce o.

It was necessary to shorten the activation time.

Comparative Example 1 [Synthesis of activated carbon fiber using PVA fiber as raw material (by rapid activation method)] Using the same raw material as that used in Example 1, dehydration and carbonization were performed under the same conditions to produce black carbon. A woven fabric made of quality fibers was obtained. When this was activated in combustion gas at 1100℃ for 30 minutes, the specific surface by the BET method using N2 was 2.
35 On? /r activated carbon fibers were obtained. The activated carbon fiber had an Ip/Io of 0.38 and a 2θ of 24.5°. Several samples were obtained by varying the activation gas, activation temperature, and time. Activation conditions and Ip/ of the obtained sample
Io and 2θ are shown in Table 1.

Comparative Example 2 [Synthesis of activated carbon fibers using phenolic fibers, acrylic fibers, and rayon fibers as raw materials] Fabrics made of fibrous phenol resin were made into carbonaceous material and then heated at 1000°C in steam. Activation was carried out for 1 hour to obtain activated carbon fibers with a specific surface area of 2300♂/g. The activated carbon fiber had an ip/io of 0.37.2θ of 23.7°C.

Also, a commercially available product made from phenolic resin is CH-2s manufactured by Kuraray Chemical Co., Ltd., but its specific surface area is 2300r+? /g and lp/lo is 0
．． It was 37.

In addition, in order to examine even finer structures, solid-state high resolution N
MR and surface reflection infrared measurements were also performed (Figures 5 and 6). The phenolic activated carbon fiber of this comparative example was 1
There was no structural difference from the polyvinyl alcohol type except that p/10 was large.

A woven fabric is made from spun yarn such as rayon fiber, and this woven fabric is soaked in an ammonium phosphate ((NH4)2PO4) aqueous solution, squeezed, dried, impregnated with 10 grams of ammonium phosphate, and then placed in N2 gas at 270°C. The mixture was heated for 30 minutes, and then the temperature was raised from 270°C to 850°C over a period of 90 minutes. 1000 in N2 gas containing 40 ml of water vapor.
Activation was performed at ℃ for 60 minutes.

From this, the specific surface area is 1650 rI! /g II) /io
A product with a value of 0.54 was obtained. l of activated carbon fiber obtained even when activation was continued until the yield reached 15%.
p/10 did not fall below 0.54. As a result, when using the usual method, Ip/
It was confirmed that those with io of 0.5 or less are difficult to obtain.

Ten units of ammonium phosphate ((NH4) 2804) were attached to a fabric made from spun yarn of acrylic fibers and heated at 270°C.
The specific surface area was 1080 rI! after being sufficiently oxidized in the air for 2 hours with free shrinkage and then activated at 1000°C for 1 hour! /g and an activated carbon fiber having an Ip/lo of 0.66 was obtained. Furthermore, even if activation was continued until the activation yield reached 1591i, it was extremely difficult to obtain a product with 1m)/10 of 0.5 or less. In addition, Table 2 shows the relationship between the activation conditions of the above samples and the findings of the samples obtained. Synthesis of activated carbon fiber with amorphous structure] A fabric made of fibrous phenol resin was made into a carbonaceous material, and then activated in steam at 1000° C. for 1 hour. The specific surface area of the obtained activated carbon fiber was 2300j/g and ip
Activated carbon fibers with /io of 0.37 were obtained. The yield at this time was 14%. Further, this was activated with steam at 900° C. for 1 hour and 50 minutes. The obtained activated carbon fiber had an ip/io of 0.20. The yield at this time was 31
Met.

Example 3 [Preparation of activated carbon powder mainly having a non-grade structure] The activated carbon fibers having a mainly non-grade structure obtained in Example 1 (synthesis number 1) were ground in a ball mill for 24 hours to obtain a powder with a mainly non-grade structure. A powdered activated carbon consisting of a structure was obtained. The particle size distribution was 99.6 inches below 350 mesh.

Usage Example 1 [Secondary battery using activated carbon fiber mainly having a non-standard structure as the positive electrode and using metallic lithium as the negative electrode] Polyvinyl alcohol-based activated carbon fiber sheet obtained in Example 1) (lp/Io= 0.07.2,300rrI
/g) as the positive electrode and metallic lithium as the negative electrode was fabricated under an argon atmosphere. Activated carbon fiber and gold lithium were placed on both poles through a glass fiber filter with a thickness of 0.5 mm. The electrolytic solution used was one in which lithium perchlorate was dissolved in propylene carbonate at a concentration of 1 mol/l. Platinum Messini was used as the current collecting electrode for both the positive and negative electrodes. The size of the activated carbon fiber sheet used was 1 cm x 1 cm, and the i amount was approximately 6119.
Met.

The constant current charging and discharging characteristics of this secondary battery were measured.

Voc (open circuit voltage) immediately after the secondary battery cell was assembled was 3.0 . The current density was set to 0.0 for activated carbon fiber.
After charging for 2 hours at 0677 A/g (assuming that the activated carbon fibers are made entirely of carbon atoms, by charging or discharging for 2 hours, adsorption and desorption of ions equivalent to 6 moles per carbon atom will occur) ) and discharged to a cell voltage of 2V.

The charging and discharging curve became stable from the 13th time of repeated charging and discharging.

FIG. 7 shows the third charge/discharge curve. Also, charge efficiency [
Percentage of charge that can be extracted within the range of cell voltage 2vt: (
Time for cell voltage to drop to 2V during discharge) + (
The relationship between the charging time) and the number of repetitions is shown in FIG.

We also confirmed that charging and discharging could be repeated up to about 20 (), and that it was possible to charge and discharge for more than that.

Other samples obtained in Example 1 and Comparative Example 1 were measured under similar conditions, and the charge efficiency and number of repetitions are similarly shown in Figure 8 (numbers in the figure correspond to synthesis numbers). . Note that the battery made of activated carbon fiber of synthesis number 7 could not be stably charged and discharged at all.

There was a clear correlation between ip/lo and electrode performance.

Those with Ip/lo of 0.3 or less had excellent performance. In particular, those with ip/Io of 0.2 or less showed extremely little deterioration due to repeated charging and discharging. ip
When /io was 0.4 or higher, charging and discharging of #1 could hardly be performed at this ion adsorption/desorption level.

Use Example 2 Various activated carbon fibers and graphite obtained in Comparative Example 2 (Experiment No. 11) (1)/10. 0.98) is used.

The cycle stability against charging and discharging was evaluated under the same conditions as in Use Example 1 (adsorption/desorption level: 6 mol %). This result is the 9th
Shown in the figure. Phenolic activated carbon fibers showed relatively good performance, but still had cycle stability of no more than 30 cycles. The other batteries could hardly be charged or discharged, so there was no problem at all in terms of performance.

From the above results, the electrode performance gradually improved when the ion adsorption/desorption level was 6 molti from the region where II)/10 was 0.4 or less, and showed remarkable improvement in the region where II)/10 was 0.3 or less. In particular, it was found that a value of 0.2 or less provides extremely excellent performance.

Use example 3 Using the activated carbon fiber with a mainly amorphous structure obtained in Example 1 (synthesis number 1), the ion adsorption/desorption level was increased to 12 molar (the current density was Charged at 0.0677 A/g for 4 hours, cell voltage 2V
(discharge ended) cycle stability was evaluated. The results are shown in FIG. Even at such extremely high levels of ion adsorption and desorption, the activated carbon fibers mainly having a non-standard structure had extremely stable performance.

Usage Example 4 [Cycle charge/discharge test when the ion adsorption/desorption level is 1 molti] Using the polyvinyl alcohol-based activated carbon fiber obtained in Example 1, a τ secondary battery cell was produced in the same manner as in Usage Example 1. After charging for 2 hours at a current density of 0.0113 A/g (adsorption and desorption of ions equivalent to 1 molti per carbon atom occurs), discharging was performed to a cell voltage of 2.8 V. The charge/discharge curve is shown in FIG. 11, and the relationship between the charge efficiency and the number of repetitions is shown in FIG. 10. 20 at the level of 1 molti
Extremely stable cycle charging and discharging was possible with a charge efficiency in the range of 100 to 97% for zero charging and discharging cycles.

Usage Example 5 A secondary battery cell was produced in the same manner as Usage Example 1 except that Li1F4 (lithium borofluoride) propylene carbonate 1 mol/Z M solution was used as the electrolyte.

Furthermore, cycle charging and discharging was performed under the same conditions as in Use Example 1. The charging/discharging curve becomes stable from the third time of charging and discharging. FIG. 12 shows the third charge/discharge curve, and FIG. 13 shows the cycle stability (the numbers in the figure correspond to the synthesis numbers).

Same below).

Use Example 6 Using the phenolic activated carbon fiber obtained in Comparative Example 3,
Propylene carbonate with LiBF4 as electrolyte) 1
A secondary battery cell was prepared and measured in the same manner as in Use Example 1 except that a solution with mol/ was used. The cycle stability is shown in FIG.

When LiBF4 was used as the electrolyte, the charge efficiency of lithium secondary batteries using phenolic activated carbon fibers as electrodes was extremely low, whereas when activated carbon fibers mainly having a non-standard structure were used, If stable cycle charging and discharging is possible, use example 7. A secondary battery cell is prepared in the same manner as in use example 1 except that metal aluminum is used as the negative electrode, and measurements are performed under the same conditions as in use example 1. mourning. After assembling the secondary battery cell, it was charged for 1 hour and then cycled for charging and discharging. 3 in Figure 14
The second charge/discharge curve is shown, and the cycle stability is shown in FIG.

Usage Example 8 [Maximum output density of activated carbon wood fiber m/Li secondary battery mainly consisting of a non-porous structure] The activated carbon fiber mainly consisting of an amorphous structure obtained in Example 1 (synthesis experiment number 1) was used as a positive electrode. Used for, thickness 0.5■
facing the lithium electrode with a glass fiber separator of 1
The maximum power density was measured in mol/l LiαOa,'pc electrolyte. The internal resistance is 20 to 30Ω, and an external resistance equal to it is installed, Pm = Vm
-1m (Vm; discharge voltage, Im; discharge current, Pm;
The maximum power density was measured from the relationship between the maximum power density and the maximum power density.
S7ctions l (J, Chem, Soc,.

Faraday Tranr, 1), 78(1
982), 3417-3429). The results are shown in Table 3.

Table 3 Maximum output density of activated carbon fiber/Li secondary battery mainly with a non-standard structure Note) Voc: open circuit voltage, R1: internal resistance Mainly with the activated carbon fiber/Li secondary battery with a non-standard structure The maximum output density of a battery depends on the open circuit voltage of the battery, but is approximately l.
θ~20 kW/kl.

Considering that the maximum output density of a lead secondary battery is 1.2 kW/kf, the secondary battery of the present invention had an extremely low output density.

Usage Example 9 [Secondary battery using activated carbon fiber with a mainly non-grade structure made from phenolic activated carbon fiber as a positive electrode and metal lithium as a negative electrode] The mainly non-grade structure obtained in Example 2 A secondary battery cell was prepared in the same manner as in Usage Example 1 using activated carbon fibers having an active carbon fiber structure, and a cycle charge/discharge test was conducted under the same conditions as in Usage Example 1 (ion adsorption/desorption level: 6 mol elI). ) However, the charge efficiency is 100 when it is over 80 cm.
Stable charging and discharging could be performed more than once.

Usage Example 10 [Secondary battery using an activated carbon powder bed with a mainly non-standard structure as the positive electrode and using metallic lithium as the negative electrode] 8 wt % was added to the activated carbon powder bed with a mainly non-standard structure obtained in Example 3.
A Teflon binder was added thereto, and the mixture was compressed at a temperature of 170°C to form a pellet. (1 cm in diameter). A secondary battery using this as a positive electrode and metallic lithium as a negative electrode was produced in the same manner as in Use Example 1. Furthermore, when cycle charging and discharging was performed under the same conditions as in usage example 1, the charge efficiency was 1 with a charge efficiency of 5 Oqb or more.
Stable charging and discharging could be performed over 00 times.

Use example 11 [Electric double layer capacitor using activated carbon fiber mainly having a non-standard structure] Polyvinyl alcohol-based activated carbon fiber sheet obtained in Example 1) (II)/1o-0,07,2300nli
An electric double layer capacitor was manufactured by using 11/g) for both positive and negative electrodes. Activated carbon fiber sheet has a thickness of 0.5
A simple glass fiber filter was installed at both poles. The electrolytic solution used was one in which lithium perchlorate was dissolved in propylene carbonate at a concentration of 1 mol/l. Platinum mesh was used for both the positive and negative electrodes for current collection. The size of the activated carbon fiber sheet used was 1 cm x 1 cm, and the weight was about 6 kg.

Furthermore, the capacitor was assembled under an argon atmosphere.

The capacitance of this capacitor was measured. After performing constant voltage charging at a voltage of 2 V for 1 hour, constant current discharging was performed, and the capacitance C) was determined from the slope of the graph (calculated from the relationship Q=CV). Cell voltage decreased almost linearly. Synthesis number 1~
The capacity was determined for the sample at 3t. Table 4 about it
It was shown to.

Table 4 Relationship between ip/lo and capacity A capacitor with a large capacity could be manufactured by using the activated carbon fiber of the present invention. In addition, the cycle stability is as follows: capacitors using any of the above samples can be charged and discharged more than 200 times.

[Brief explanation of the drawing]

Figure 1 is an X-ray intensity curve diagram of a conventional acrylic activated carbon fiber, and Figures 2 to 4 are X-ray diffraction intensity curve diagrams, solid-state high-resolution NMR spectrum diagrams, and surface reflection diagrams of activated carbon fibers of the present invention, respectively. It is an infrared spectrum diagram. Further, FIGS. 5 and 6 are a solid-state high-resolution NMR spectrum and a surface reflection infrared spectrum, respectively, of a conventional 7-enol-based activated carbon fiber. Furthermore, Fig. 7 to Fig. 15 are diagrams for showing the ion adsorption/desorption ability of various carbon materials and their stability.
Figures 12 and 14 are charge/discharge curve diagrams.
9, 10, 13, and 15 are diagrams showing cycle stability.

Claims (5)

[Claims] (1) The graphitic crystalline structure parameter Ip/Io at the diffraction peak of the (002) plane of the X-ray diffraction intensity curve is 0.
Activated carbon that is 3 or less. Here, Ip is the maximum value of the intensity above the tangent line drawn on both sides of the diffraction peak of the (002) plane,
Io is the X-ray intensity remaining after subtracting the air scattering intensity from the measured diffraction intensity at the diffraction angle 2θ indicating Ip. (2) Claim 1, in which the activated carbon has a fibrous form.
Activated carbon as described in section. (3) Activated carbon according to claim 1, characterized in that a polyvinyl alcohol resin is used as a starting material. (4) Activated carbon according to claim 1, which uses polyvinyl alcohol fiber as a starting material. (5) The activated carbon according to claim 1, 2, 3, or 4, wherein Ip/Io is 0.2 or less.