JP2000036296A - Battery member and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery member suitable for a separator or the like of a non-aqueous battery, especially a lithium primary battery or a secondary battery, a paper battery of the like, and its manufacturing method. SOLUTION: This battery member is composed of a porous body comprising a polymer having a three-dimensionally continuous network skeleton of, and the polymer is block copolymer having a hard block part and a soft block part comprising crystalline polyolefins, or syndiotactic 1,2-polybutadiene. The manufacturing method is a method for manufacturing the battery member by removing low molecule material, after forming the porous body comprising the polymer having a three-dimensionally continuous network skeleton of by mixing the block copolymer having a hard block part and a soft block part comprising crystalline polyolefins, or syndiotactic 1,2-polybutadiene with the low molecule material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery member and a method of manufacturing the same, and more particularly, to a battery member used as a separator for a non-aqueous battery, particularly a lithium primary battery, a secondary battery, a paper battery, and the like, and a battery member therefor. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, battery members used for non-aqueous batteries, particularly spiral-type lithium primary batteries and secondary batteries, other primary batteries and secondary batteries using an organic electrolyte, paper batteries, etc., such as separators, have been used. Attempts have been made to apply polymer films such as polyolefins and porous bodies such as nonwoven fabrics. Specifically, it has been proposed to use a porous body made of polyethylene as a separator for a lithium ion secondary battery (Japanese Patent Laid-Open No. 8-641).
No. 94). In this publication, the advantage of using a porous body made of polyethylene is that when the battery is short-circuited externally, the temperature rises inside the battery due to Joule heat caused by the short-circuited battery. By forming into a film, the rise in battery temperature is prevented,
It is disclosed that the ignition point of the organic electrolyte solution held inside the separator does not reach the flash point and a fire accident or the like can be prevented. However, as shown in the schematic diagram of FIG. 1, a conventional separator made of a porous body has a substantially constant communication diameter (d ′). There is a problem that the performance at the time cannot be maintained. Such a problem also causes a bad effect at the time of manufacturing a battery. That is, although the impregnation with the electrolyte is facilitated, the electrolyte also flows out at the same time, so that an undesirable situation such as an increase in the number of steps at the time of injecting the electrolyte or an accident due to the leaked electrolyte is caused.

[0003]

Under such circumstances, the present invention is used for non-aqueous batteries, especially for separators such as lithium primary batteries, secondary batteries, and paper batteries.
An object of the present invention is to provide a practical battery member which has excellent electrolyte solution holding ability, hardly allows the electrolyte solution to flow out, and can reduce the number of steps in its manufacture, and a method for manufacturing the same.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to develop a battery member having the above-mentioned preferable properties. As a result, a polymer having a three-dimensional continuous network skeleton was used as a material for the battery member. It has been found that the object can be achieved by using a porous body having a specific structure made of a polymer. The present invention has been completed based on such findings. That is, the present invention is a battery member using a porous body made of a polymer having a three-dimensional continuous network skeleton, wherein the polymer has a hard block portion and a soft block portion made of crystalline polyolefin. It is intended to provide a battery member characterized by being a block copolymer or syndiotactic 1,2-polybutadiene having the same. Further, the present invention is a tertiary polymer comprising a mixture of a block copolymer or a syndiotactic 1,2-polybutadiene having a hard block portion and a soft block portion made of a crystalline polyolefin, and a low molecular material, and a high molecular weight polymer. Another object of the present invention is to provide a method for producing a battery member, wherein a porous body is obtained by removing a low-molecular material after forming an original continuous network skeleton.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Most of the conventional porous bodies made of a communicable high molecular polymer have substantially the same cell diameter D and the same communication diameter d. When such a porous body is impregnated with a liquid, the liquid easily enters the pores but easily flows out. Therefore, in a porous body having a structure in which d is smaller than D, even if there is some difficulty in impregnating the liquid, once the liquid has entered the cell, it is very difficult for the liquid to flow out (the liquid retaining property is low). High) characteristics. Such a porous body having a cell diameter and a communication diameter greatly different from each other, that is, a so-called double porous body, is hereinafter referred to as a double porous body. FIG. 2 is a schematic diagram showing an example of such a double porous body. As shown in FIG.
When the communication diameter d connecting the cells is smaller than the cell diameter D, the liquid once impregnated into the cell from the outside is sealed and held as it is because the communication diameter serving as the inlet and outlet is small. The rate of the leap jumps dramatically. In the battery member of the present invention, as a material thereof, a porous body made of a polymer having a three-dimensional continuous network skeleton, particularly a double-pored body, wherein the polymer is a hard body made of a crystalline polyolefin. A block copolymer having a block portion and a soft block portion or one that is a syndiotactic 1,2-polybutadiene is used.

In this porous body, the average cell diameter D is
The average cell diameter D is preferably larger than the average communication diameter d communicating the cells, and the average cell diameter D is preferably in the range of 0.1 to 50 μm. If the average cell diameter D is less than 0.1 μm, the proportion of the cell skin is large, and the amount of liquid that can be sealed and held may be small. If the average cell diameter D exceeds 50 μm, the strength of the porous body is reduced, and battery assembly becomes difficult. May be possible. Considering the amount of liquid that can be sealed and held and the strength of the porous body, the more preferable range of the average cell diameter D is 0.2 to 0.2.
It is 20 μm, and particularly preferably in the range of 0.5 to 10 μm. On the other hand, the average communication diameter d is preferably in the range of 0.01 to 10 μm. When the average communication diameter d is less than 0.01 μm, the fluidity of the liquid flowing through the communication hole may be impaired. When the average communication diameter d exceeds 10 μm, the liquid once impregnated easily flows out, and the liquid holding effect is reduced. It may cause a decrease. From the viewpoint of the balance between the fluidity of the liquid passing through the communication hole and the liquid holding effect, a more preferable range of the average communication diameter d is 0.05 to 7 μm, particularly 0.1 to 5 μm.
The range of μm is preferred. The ratio d / D of the average communication diameter d to the average cell diameter D is preferably in the range of 0.01 to 0.50. If the d / D ratio is less than 0.01, the fluidity of the enclosed liquid may be impaired, and the d / D ratio may be less than 0.50.
If it exceeds, the liquid holding effect may be reduced. From the viewpoint of the balance between the fluidity of the enclosed liquid and the liquid holding effect, a more preferable range of the d / D ratio is 0.03 to 0.4.
0, and particularly preferably in the range of 0.05 to 0.30.

The porous material used in the battery member of the present invention is
A porous body made of a high molecular polymer having a three-dimensional continuous network skeleton, particularly a double porous body, can be produced by various methods, preferably a hard block portion made of crystalline polyolefin and Block copolymer or syndiotactic 1,2 having a soft block portion
-It can be produced by removing a low molecular weight material from a mixture of polybutadiene (hereinafter sometimes referred to as SPBD) and a low molecular weight material. Examples of the block copolymer include (1) a copolymer having a crystalline polyethylene block (hard block portion) and a polybutene block (soft block portion), and (2) a crystalline polyethylene block (hard block portion) and polyethylene. / Butylene block (soft block portion) and a copolymer having
(3) Crystalline polyethylene block (hard block part)
(4) a copolymer having a crystalline polypropylene block (a hard block portion) and a polyethylene-propylene random block (a soft block portion), and (5) a copolymer having a polyvinyl acetate block (a soft block portion).
A copolymer having a crystalline polyethylene block (a hard block portion) and a block containing a polypropylene (a soft block portion) can be preferably exemplified.

[0008] These copolymers and SPBD may be used alone or in combination of two or more. However, if two or more kinds having different crystal structures and crystallinities are mixed and used, the need becomes more serious. It is preferable because characteristics suitable for the above can be obtained. Furthermore, such two or more copolymers and SP
By manufacturing a porous body using BD as a multilayer thin film, a double porous film having a gradient structure can be obtained. This is an excellent material for a battery member that can respond to diversification of needs. It is desirable that the porous body used in the battery member of the present invention is softer than that obtained from a general plastic. This is because it is expected that the gel body is soft when the electrolyte solution is contained, and that more liquid can be enclosed. However, if it is too soft, the strength of the porous body itself will be insufficient. Therefore, the dynamic storage shear modulus G ′ of the porous body at a temperature of 25 ° C. is improved in the shape following property of the porous body when the porous body is combined with the electrode, and further, the process when the electrolyte is impregnated. From the viewpoint that the number can be reduced, the range is preferably 5 to 5000 kg / cm ² , more preferably 10 to 1000 kg / cm ² , and still more preferably 20 to 500 kg / cm ² .

It is preferable to appropriately select from the above copolymers so as to obtain a porous body having such a dynamic storage shear modulus G ′. When producing the porous body according to the present invention, the low-molecular material to be mixed with the copolymer is not particularly limited, and may be a solid or a liquid, and various organic materials can be used. Is less than 20,000, preferably 10,000 or less, more preferably 500
Those below 0 are advantageous. Examples of such a low-molecular material include the following materials. Softeners: Various rubber or resin softeners such as mineral oils, vegetable oils, and synthetic oils. Here, examples of the mineral oils include aromatic, naphthenic and paraffinic process oils. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, wood wax, pine oil, olive oil, and the like.

Plasticizers: Various ester plasticizers such as phthalic acid ester, phthalic acid mixed ester, aliphatic dibasic acid ester, glycol ester, fatty acid ester, phosphoric acid ester, stearic acid ester, epoxy plasticizer, and others Plasticizers for plastics or NBR plasticizers such as phthalate, adipate, sebacate, phosphate, polyether and polyester. Tackifiers: Various tackifiers (tackifiers) such as coumarone resin, coumarone-indene resin, phenol terpene resin, petroleum hydrocarbons, and rosin derivatives. Oligomer: Crown ether, fluorinated oligomer, polyisobutylene, xylene resin, chlorinated rubber, polyethylene wax, petroleum resin, rosin ester rubber, polyalkylene glycol diacrylate, liquid rubber (polybutadiene, styrene-butadiene rubber, butadiene-acrylonitrile rubber, poly) Various oligomers such as chloroprene rubber), silicone-based oligomers, and poly-α-olefins.

Lubricants: hydrocarbon lubricants such as paraffin and wax; fatty acid lubricants such as higher fatty acids and oxy fatty acids; fatty acid amide lubricants such as fatty acid amides and alkylene bis fatty acid amides; fatty acid lower alcohol esters; fatty acid polyhydric alcohol esters Ester lubricants such as fatty acid and polyglycol esters; alcohol-based lubricants such as aliphatic alcohols, polyhydric alcohols, polyglycols and polyglycerin; metal soaps; and mixed lubricants. In addition, latex, emulsion, liquid crystal, bituminous composition, clay, natural starch, sugar, inorganic silicone oil, phosphazene, etc. are also suitable as low molecular weight materials. Animal oils such as cow oil, pork oil, horse oil, bird oil or fish oil: honey, fruit juice, dairy products such as chocolate or yogurt, hydrocarbons, halogenated hydrocarbons, alcohols, phenols, ethers system,
Organic solvents such as acetal-based, ketone-based, fatty acid-based, ester-based, nitrogen compound-based, and sulfur compound-based: or various medicinal ingredients, soil modifiers, fertilizers, petroleum, water, and aqueous solutions are suitable. These components may be used alone or in combination of two or more.

[0012] These low molecular weight materials include the above copolymers and S
It is held between the three-dimensional continuous network skeletons composed of PBDs (particularly in the internal communication space). In this case, it is necessary to form the three-dimensional continuous network skeleton with as little copolymer or SPBD as possible. Is preferred. When the amount of the copolymer or SPBD constituting the three-dimensional continuous network skeleton is A and the amount of the low-molecular material is B, the weight fraction of the copolymer [{A / (A + B)} × 100] Is preferably 30% or less, more preferably 7 to 25%, and most preferably 10 to 25%.
It is in the range of 20%. The battery member made of the porous body or the double porous body of the present invention uses, for example, a high-shear mixer,
After thoroughly mixing at least one selected from the copolymer or SPBD and at least one selected from the low-molecular materials at a predetermined ratio,
Formed into a polymer network structure of desired shape such as a sheet,
It can then be manufactured by removing the low molecular material in the structure.

The method for removing the low-molecular material is not particularly limited. For example, a method in which the low-molecular material is dissolved and extracted using an appropriate solvent and the remaining solvent is volatilized and dried is preferably used. Here, the solvent used is not particularly limited as long as the copolymer is insoluble or hardly soluble and the low molecular weight material is easily soluble.
Various things can be used. Preferred examples of such a solvent include ketone solvents such as acetone and methyl ethyl ketone, alcohol solvents such as methanol and ethanol, and hydrocarbon solvents such as decane and undecane. As an operation for performing dissolution extraction using these solvents, for example, it is preferable to extract a low-molecular material by immersing a sheet-like polymer network structure containing a low-molecular material in the solvent. In this way,
The battery member of the present invention, which is constituted by a porous body made of a polymer having a three-dimensional continuous network skeleton, particularly a double porous body, is obtained. Next, a battery using the battery member of the present invention will be described. A battery using the battery member of the present invention is a battery in which the porous body in the above-described battery member, particularly a double porous body having an electrolyte held in a network skeleton, is mounted as a separator. There is no particular limitation on the method of retaining an electrolyte in the porous body or the double porous body (hereinafter, the porous body and the double porous body are sometimes collectively referred to as “(double) porous body”). Using a general method of impregnating, such as a method of sufficiently defoaming under a high vacuum and then impregnating with an electrolytic solution, a method of impregnating in a high temperature state or a stretched state, and a method of promoting impregnation by applying vibration. can do.

The following two methods can be considered as methods for dramatically improving the impregnation of the electrolytic solution. First, the first method is a method in which the surface activity is increased by irradiating a (double) porous body with high energy to increase the affinity with the electrolytic solution. Examples of the high energy source used at this time include plasma, sputter, electron beam, ozone, corona discharge, etc. Among them, plasma discharge is particularly effective and greatly improves the impregnation of the electrolyte. be able to. Next, a second method is to improve the impregnation property of the electrolyte by coating the (double) porous cell walls with a polymer or the like having a high affinity for the electrolyte. As the polymer having a high affinity for the electrolyte used at this time, a polymer having high polarity is desirable, and for example, thermoplastic polyurethane, polyethylene oxide, polyvinylidene fluoride, polyester polycarbonate, and a copolymer thereof are suitable. . In order to coat these polymers on the cell wall, a solution obtained by dissolving the above polymer in a solvent is impregnated in a (double) porous body, and then the solvent is volatilized.

The electrolyte to be impregnated into the (double) porous body may be any non-aqueous electrolyte, and is not particularly limited. Examples thereof include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethoxyethane, diethyl carbonate, and the like. Dimethoxyethane, dipropyl carbonate, mixtures thereof and the like can be used. The type of battery obtained by using the battery member of the present invention may be any of a primary battery and a secondary battery as long as the battery uses a non-aqueous electrolyte. Examples of such a battery include a spiral-wound lithium primary battery, a lithium ion secondary battery, and a paper battery.

[0016]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 15% by weight of an ethylene-butene copolymer having an ethylene crystal part and 85% by weight of dioctyl adipate were mixed at a temperature of 180 ° C. and a rotation speed of 2500 rpm using a high shear mixer.
After mixing under the conditions described above to produce a thin film-like polymer network structure, dioctyl adipate in the structure is removed using acetone to form a thin film-like double-porous film having a three-dimensional continuous network skeleton. I got a body. This porous body has an average cell diameter D of 10 μm, an average communication diameter d of 1.5 μm, a d / D ratio of 0.15, and a dynamic storage shear modulus G ′ at a temperature of 25 ° C.
Was 60 kg / cm ² . Next, this double porous body is subjected to plasma treatment in an argon gas atmosphere, and then immersed in an electrolyte solution composed of propylene carbonate at room temperature for 30 seconds and pulled up. Then, the surface of the porous body is lightly blotted with blotting paper. By wiping, a porous body in which the electrolyte was sealed was obtained.
The weight ratio of the porous body after sealing the electrolyte to the porous body before sealing the electrolyte was 5.7, indicating that a gel electrolyte holding a large amount of the electrolyte was obtained. Further, the state in which the electrolytic solution was held was extremely stable, and the exudation of the electrolytic solution was very small.

Example 2 In the same manner as in Example 1 except that 15% by weight of a propylene-ethylene copolymer having a propylene crystal part and 85% by weight of dioctyl phthalate were used, a thin film having a three-dimensional continuous network skeleton was used. A heavy porous body was obtained. This porous body has an average cell diameter D of 6 μm, an average communication diameter d of 0.5 μm, and a d / D ratio of
0.08, the dynamic storage shear modulus G ′ at a temperature of 25 ° C. was 130 kg / cm ² . Next, this double porous material is subjected to a plasma treatment in an oxygen gas atmosphere, and then is placed in an electrolyte solution of propylene carbonate at room temperature for 30 minutes.
After dipping for 2 seconds and pulling up, the surface of the porous body was lightly wiped with blotting paper to obtain a porous body in which an electrolyte was sealed. The weight ratio of the porous body after the electrolyte was sealed to the porous body before the electrolyte was sealed was 5.2, indicating that a gel electrolyte holding a large amount of the electrolyte was obtained. Further, the state in which the electrolytic solution was held was extremely stable, and the exudation of the electrolytic solution was very small.

Example 3 Example 1 was prepared using 18% by weight of syndiotactic 1,2-polybutadiene and 82% by weight of dibutyl phthalate.
In the same manner as in, a thin film-like double porous body having a three-dimensional continuous network skeleton was obtained. This porous body has an average cell diameter D of 5 μm.
m, average communication diameter d is 1 μm, d / D ratio is 0.2, temperature 25
Dynamic storage shear modulus G ′ at 80 ° C. is 80 kg / cm ²
Met. Next, this double porous body is subjected to plasma treatment in an argon gas atmosphere, and then immersed in an electrolyte solution composed of propylene carbonate at room temperature for 30 seconds and pulled up. Then, the surface of the porous body is lightly blotted with blotting paper. By wiping, a porous body in which the electrolyte was sealed was obtained. The weight ratio of the porous body after the electrolyte was sealed to the porous body before the electrolyte was sealed was 5.5, indicating that a gel electrolyte holding a large amount of the electrolyte was obtained. Further, the state in which the electrolytic solution was held was extremely stable, and the exudation of the electrolytic solution was very small.

Example 4 Ethylene-vinyl acetate copolymer 1 having an ethylene crystal part
Using 3% by weight and 87% by weight of a mixture of diethyl phthalate and dibutyl phthalate, in the same manner as in Example 1,
A thin film-like double porous body having a three-dimensional continuous network skeleton was obtained. This porous body had an average cell diameter D of 3 μm, an average communication diameter d of 0.2 μm, a d / D ratio of 0.7, and a dynamic storage shear modulus G ′ at a temperature of 25 ° C. of 100 kg / cm ² . .
Next, this double porous body was subjected to plasma treatment in an oxygen gas atmosphere, and then immersed in an electrolyte solution composed of propylene carbonate at room temperature for 30 seconds and pulled up.
The surface of the porous body was lightly wiped with blotting paper to obtain a porous body in which the electrolyte was sealed. The weight ratio of the porous body after sealing the electrolyte to the porous body before sealing the electrolyte was 5.0, indicating that a gel electrolyte holding a large amount of the electrolyte was obtained. Further, the state in which the electrolytic solution was held was extremely stable, and the exudation of the electrolytic solution was very small.

Example 5 A thin film having a three-dimensional continuous network skeleton was prepared in the same manner as in Example 1, except that 15% by weight of an ethylene-ethylenebutylene block copolymer having an ethylene crystal part and 85% by weight of dioctyl phthalate were used. Was obtained. This porous body has an average cell diameter D of 5 μm, an average communication diameter d of 0.5 μm,
The dynamic storage shear modulus G ′ at a d / D ratio of 0.1 and a temperature of 25 ° C. was 100 kg / cm ² . Next, this double porous body is subjected to plasma treatment in an argon gas atmosphere,
Next, this was immersed in an electrolyte solution composed of propylene carbonate at room temperature for 30 seconds and pulled up, and then the surface of the porous body was lightly wiped with blotting paper to obtain a porous body in which the electrolyte solution was sealed. The weight ratio of the porous body after the electrolyte was sealed to the porous body before the electrolyte was sealed was 5.2, indicating that a gel electrolyte holding a large amount of the electrolyte was obtained. Further, the state in which the electrolytic solution was held was extremely stable, and the exudation of the electrolytic solution was very small.

Example 6 Ethylene-propylene copolymer 2 having an ethylene crystal part 2
0% by weight and 80% by weight of dioctyl adipate,
In the same manner as in Example 1, a thin-film double porous body having a three-dimensional continuous network skeleton was obtained. This porous body has an average cell diameter D of 10 μm, an average communication diameter d of 1.5 μm, and a d / D ratio of 0.
15. Dynamic storage shear modulus G ′ at a temperature of 25 ° C. is 2
It was 0 kg / cm ² . Next, this double porous body is subjected to a plasma treatment in an argon gas atmosphere, and is then placed in an electrolyte solution of propylene carbonate at room temperature for 30 minutes.
After dipping for 2 seconds and pulling up, the surface of the porous body was lightly wiped with blotting paper to obtain a porous body in which an electrolyte was sealed. The weight ratio of the porous body after sealing the electrolyte to the porous body before sealing the electrolyte was 4.5, indicating that a gel electrolyte holding a large amount of the electrolyte was obtained. Further, the state in which the electrolytic solution was held was extremely stable, and the exudation of the electrolytic solution was very small.

[0022]

The battery member of the present invention is composed of a porous body made of a high molecular polymer having a three-dimensional continuous network skeleton, and is a non-aqueous battery, particularly a lithium primary battery or a secondary battery. It is suitably used as a separator for paper batteries and the like.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a structure of an example of a porous body constituting a conventional separator.

FIG. 2 is a schematic view showing a structure of an example of a porous body constituting a battery member of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01M 10/40 H01M 10/40 Z F term (Reference) 4F074 AA10 AA16B AA17B AA22B AA24B AA25C AA26B AD05 AG02 AG11 AG14 AG20 CB03 CB13 CB16 CD11 CE15 CE34 CE98 DA03 DA08 DA49 4J002 AC041 AG002 BB021 BB031 EH007 FD022 FD026 FD176 FD207 GQ01 5H021 BB12 BB13 CC00 EE04 EE05 EE15 EE23 HH00 HH03 HH08 BB09H02 BB07 EJ14 HJ00 HJ06 HJ14

Claims (6)

[Claims] 1. A battery member using a porous body made of a polymer having a three-dimensional continuous network skeleton, wherein the polymer has a hard block portion and a soft block portion made of crystalline polyolefin. A battery member comprising a block copolymer or a syndiotactic 1,2-polybutadiene. 2. The block copolymer has (1) a crystalline polyethylene block (hard block portion) and a polybutene block (soft block portion).
(2) Crystalline polyethylene block (hard block part)
And polyethylene / butylene block (soft block)
(3) a copolymer having a crystalline polyethylene block (hard block portion) and a polyvinyl acetate block (soft block portion), (4) a crystalline polypropylene block (hard block portion) and polyethylene −
It is selected from a copolymer having a propylene random block (soft block portion) and a copolymer having (5) a crystalline polyethylene block (hard block portion) and a block containing polypropylene (soft block portion). The battery member according to claim 1. 3. A cell diameter D formed in the network skeleton.
The battery member according to claim 1 or 2, wherein a diameter of the battery member is larger than an average communication diameter d communicating between the cells. 4. The battery member according to claim 1, wherein the dynamic storage shear modulus G ′ of the porous body at a temperature of 25 ° C. is 5 to 5000 kg / cm ² . 5. A three-dimensional polymer comprising a mixture of a block copolymer or a syndiotactic 1,2-polybutadiene having a hard block portion and a soft block portion comprising a crystalline polyolefin and a low molecular material, and comprising a high molecular polymer. A method for producing a battery member, wherein a porous body is obtained by forming a continuous network skeleton and then removing the low-molecular material. 6. The method according to claim 5, wherein an electrolyte is further injected into the porous body.