Patent Publication Number: US-2012034391-A1

Title: Manufacturing process for porous material

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/371,293, filed on Aug. 6, 2010, the entirety of which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a manufacturing process for a porous material, and in particular to a manufacturing process for a porous material using surfactants as the pore former incorporated with continuous roll-to-roll processes. 
     2. Description of the Related Art 
     Generally, porous materials are materials with porous structures. According to the International Union of Pure and Applied Chemistry (IUPAC), porous materials can be divided into three types, such as microporous, mesoporous, and macroporous materials. The microporous materials comprise pores of diameters substantially less than 2 nm, the macroporous materials comprise pores of diameters substantially greater than 50 nm, and the mesoporous materials comprise pores of diameters among 2-50 nm. 
     Surfactants typically comprise organic amphiphilic molecules having hydrophilic and hydrophobic groups and can be dissolved in organic solutions and aqueous solutions. When the surfactant concentration in water is low, molecules of the surfactant will be located at the interface between air and water. When the surfactant concentration is increased to a critical micelle concentration (CMC), the surfactants will aggregate to be the micelles. The hydrophilic group of surfactant in micelle will face outward to reduce a contact area between the water molecules and the hydrophobic groups. 
     A hydrophilic-lipophilic balance (HLB) of a surfactant is the hydrophilic degree of the surfactants. A surfactant with higher HLB value has higher hydrophilicity. For example, surfactants with HLB values of 8 or higher have high water solubility. 
     Since the solution concentration is greater than the critical micelle concentration, surfactant molecules will aggregate to form the micelle. Although the micelle is typically formed in a spherical shape, the size and shape of the micelle can be gradually changed in accordance with variations in concentration and temperature. In addition, the size and shape of the micelle are also influenced by the chemical structure and molecular weight of the surfactant. Based on formation conditions and compositions, liquid crystals comprise thermotropic liquid crystals and lyotropic liquid crystals. The thermotropic liquid crystals are formed due to temperature variations, and the lyotropic liquid crystals are formed due to concentration variations. 
     Based on the organization of molecules or surfactant aggregates, liquid crystals comprise a smectic and nematic mesophase. In the nematic phase, all molecules or surfactant aggregates are aligned approximately parallel to each other with only a one-dimensional (orientational) order. In the smectic phase, all molecules or surfactant aggregates exhibit both (two-dimensional) positional and orientational order. 
     In the prior art, one of the manufacturing processes for ordered mesoporous materials uses various surfactants as structure-directing agents or so-called templates. The surfactants can be, for examples, triblock copolymers, diblock copolymers or ionic surfactants. The above method also uses alkoxides as a precursor to synthesize metal oxides or hydroxides by a sol-gel technique. Alternatively, the above method may use carbonaceous monomers or oligomers as precursors of carbons to mix with surfactants and then the surfactants are removed as the surfactants are arranged orderly and the precursors are polymerized. The obtained polymers are then carbonized at a high temperature such that highly ordered mesoporous carbons are obtained. However, the research to date about formation of the mesoporous materials mainly focuses on changing the synthesis conditions of the precursors or the materials. For example, U.S. Pat. Nos. 5,057,296, 5,108,725, 5,102,643 and 5,098,684 disclose using ionic surfactants as a template for manufacturing porous materials, wherein pore sizes thereof are greater than 5 nm. However, the formed mesoporous structures are not stable. 
     The conventional manufacturing processes for highly ordered mesoporous materials are typically by template-directed synthesis. The methods thereof can be divided into hard template methods and soft template methods according to features and restrictions of the template used therein. Since Kresge et al. disclosed a synthesis method for forming mesoporous silica in 1992 (C. T. Kresge, M. E. Leonowicz, W. J. Roth, J. C. Vartuli, and J. S. Beck, “Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism” Nature, vol 359, no. 6397, pp. 710-712, 1992), research about manufacturing mesoporous materials by template methods have been developed in the last decade. More precisely, research about manufacturing mesoporous materials by template methods that mainly focus on selections of surfactant and the conditions of material synthesizing has been carried out. For the soft template method, through selecting the surfactants and adjusting the synthesis conditions, the surfactants as a structure-directing agent will self-assemble into a highly ordered liquid crystalline phase while the concentration of the surfactant is greater than the critical micelle concentration, thereby forming various types of highly ordered mesoporous channels such as MCM-41, SBA-15 and MCM-50 having a two-dimensional high symmetry, and KIT-5, SBA-16, SBA-11, SBA-2, MCM-48, etc. having a three-dimensional high symmetry. For the hard template method, a previously prepared mesoporous silicon dioxide, such as SBA-15, is used as a template to prepare reversed mesoporous materials. After mixing carbon precursors with SBA-15, the carbon precursors are converted to carbon. The silicon dioxide in the obtained product is removed by using hydrofluoric acid or strong bases and then the ordered mesoporous carbon named as CMK-3 is obtained. Although highly ordered mesoporous materials having microstructures can also be obtained, the cost of the hard template method is high and the structures of the obtained materials are reversed mesoporous structures. 
     The highly ordered mesoporous materials synthesized by using surfactants as structure-directing agents have characteristics such as high specific surface areas, uniform and adjustable pore sizes, and regular pore channel arrangements such that high value in applications such as separation, catalyst, electromagnetic materials, and chemical sensing can be seen, wherein the representative materials are mesoporous silicon dioxides. 
     In the prior art, the metal hydroxide or metal oxide are obtained by a precipitation, hydrolysis, condensation and redox reaction in batch process. In a batch process, the concentration gradient of reactant exists. Therefore, it is hard to control the uniformity of conversion. With a scale-up design in a conventional batch process, there are disadvantages of poor reaction uniformity and unstable quality. 
     BRIEF SUMMARY OF THE INVENTION 
     In one embodiment of the present invention, a continuous process for manufacturing a porous material is provided. The manufacturing process for a porous material includes the steps of: mixing a non-ionic surfactant with a precursor of a predetermined material to form a mixture comprising a continuous phase and a liquid crystalline mesophase comprising the non-ionic surfactants, wherein the precursor is essentially located in the continuous phase; coating or depositing the mixture onto a flexible substrate; and converting the precursor of the predetermined material. 
     In one embodiment of the present invention, the continuous process further includes coating or depositing a base onto a layer comprising the precursor of the predetermined material. 
     In another embodiment of the present invention, the continuous process further includes coating or depositing a base precursor or a mixture of a base and a fugitive acid onto a layer comprising the precursor of the predetermined material. 
     In a further embodiment of the present invention, the continuous process further includes adding a base precursor or a mixture of a base and a fugitive acid into the mixture. 
     Preferably, the liquid crystalline mesophase is a smectic phase or a smectic hexagonal phase. The liquid crystalline mesophase is the form of a column having a diameter from about 2 nm to about 20 nm. 
     Preferably, the non-ionic surfactants have the HLB value from 5 to 24. More preferably, the non-ionic surfactants have the HLB value from 10 to 14. 
     The mixture comprises two continuous phases, or a continuous liquid crystalline mesophase and a continuous non-liquid crystalline phase. 
     In further another embodiment of the present invention, the continuous process further includes coating or depositing the mixture onto the flexible substrate in a roll-to-roll manner. 
     Preferably, the flexible substrate comprises a metal or polymer. 
     In an embodiment of the present invention, the continuous process further includes heating or drying, after converting the precursor of the predetermined material, and removing the surfactants, wherein removing the surfactants comprises washing the surfactants by a solvent or a solvent mixture. 
     The precursor is converted to obtain the predetermined material by precipitation, hydrolysis, condensation, redox reaction, polymerization, or crosslinking. 
     The mixture is coated or deposited onto the flexible substrate by casting, impregnation, spraying, dipping, gravure, doctor blade, slot, slit, curtain, reverse or transfer coating, or printing. 
     The predetermined material is selected from the group consisting of silicon dioxide, titanium dioxide, nickel hydroxide, nickel oxide, and manganese oxide. 
     The precursor includes tetraethoxysilane, titanium salt, organotitanium, titanium alkyoxide, nickel salt, organonickel complex, manganese salt, organomanganese complex, or combinations thereof. 
     Preferably, the non-ionic surfactants comprise a block, graft, or branch copolymer. 
     More preferably, the non-ionic surfactants comprise ethylene oxide (EO) copolymer, propylene oxide (PO) copolymer, butylene oxide copolymer, vinyl pyridine copolymer, vinyl pyrrolidone, epichlorohydrin copolymer, styrene copolymer, acrylic copolymer, or combinations thereof. 
     Alternatively, the non-ionic surfactants comprise polyoxyethylene alkylether having a chemical formula of C x H 2x+1 ( EO) y H, where EO represents an ethylene oxide, x is not less than 12, and y is not less than 6. 
     Preferably, the molecular weight of the non-ionic surfactants is between 500 and 20000. More preferably, the molecular weight of the non-ionic surfactants is between 600 and 10000. 
     In an embodiment of the present invention, the continuous process further includes adding a swelling agent into the mixture. 
     In another embodiment of the present invention, a process for manufacturing a porous material includes the steps of: mixing a non-ionic surfactant with a precursor of a predetermined material and either a base precursor or a first mixture of a base and a fugitive acid to form a second mixture comprising a continuous phase and a liquid crystalline mesophase comprising the non-ionic surfactants, wherein the precursor is essentially located in the continuous phase; coating or depositing the second mixture onto a flexible substrate; heating or illuminating the base precursor or the first mixture of the base and the fugitive acid; and converting the precursor of the predetermined material. 
     Preferably, the base precursor or the mixture of the base and the fugitive acid is a nitrogen-containing compound, guanidine, urea, amine, imine, or derivatives thereof. The base precursor or the mixture of the base and the fugitive acid is heated under a temperature ranging from 30° C. to 150° C. 
     In further another embodiment of the present invention, a process for manufacturing a porous material includes the steps of: mixing a non-ionic surfactant with a precursor of a predetermined material to form a mixture comprising a continuous phase and a liquid crystalline mesophase comprising the non-ionic surfactants, wherein the precursor is essentially located in the continuous phase; coating or depositing the mixture onto a flexible substrate; coating or depositing a base precursor or a mixture of a base and a fugitive acid onto a layer comprising the precursor of the predetermined material; heating or illuminating the base precursor or the mixture of the base and the fugitive acid; and converting the precursor of the predetermined material. 
     In one embodiment of the present invention, a continuous process for manufacturing an electrode includes the steps of mixing a non-ionic surfactant with a precursor of a predetermined material to form a mixture comprising a continuous phase and a liquid crystalline mesophase comprising the non-ionic surfactants, wherein the precursor is essentially located in the continuous phase; coating or depositing the mixture onto a metal substrate; and converting the precursor of the predetermined material. 
     In another embodiment of the present invention, a continuous process for manufacturing porous material includes the steps of: mixing a surfactant with a nickel salt or organonickel complex to form a mixture; adding a silver halide and a developing agent or reducing agent into the mixture; coating or depositing the mixture onto a flexible substrate; reacting the silver halide with the developing agent or reducing agent under illumination; and converting the nickel salt or organonickel complex to obtain nickel hydroxide. 
     In a further embodiment of the present invention, a continuous process for manufacturing an electrode includes the steps of: mixing a surfactant with a nickel salt or organonickel complex to form a mixture; adding a silver halide and a developing agent or reducing agent into the mixture; coating or depositing the mixture onto a metal substrate; reacting the silver halide with developing agent or reducing agent under illumination; and converting nickel salt or organonickel complex to obtain nickel hydroxide. 
     Preferably the developing agent or reducing agent comprises an organic compound, hydroquinone, aminophenol, phenylene diamine, derivatives thereof, or combinations thereof. More preferably, the developing agent or reducing agent comprises methyl p-aminophenol, N-methyl-p-aminophenol salt, 1-phenyl-3-pyrazolidinone, derivatives thereof, or combinations thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, where: 
         FIG. 1  is a flow chart of a manufacturing process for porous materials of the invention; 
         FIGS. 2   a ,  2   b  and  2   c  are schematic diagrams showing a continuous roll-to-roll coating process of the invention, respectively; 
         FIGS. 3   a  and  3   b  are schematic diagrams showing a continuous roll-to-roll removing, drying, and scraping steps of the invention, respectively; 
         FIG. 4  is a schematic diagram showing a continuous roll-to-roll electrode cutting step of the invention; 
         FIGS. 5   a ,  5   b ,  5   c ,  5   d , and  5   e  are schematic diagrams showing a roll-to-roll manufacturing process for silver-containing porous materials of the invention; 
         FIG. 6   a  is a plot for the isotherm of the porous nickel hydroxide of Example 1; 
         FIG. 6   b  is a plot for the pore size distribution of the porous nickel hydroxide of Example 1; 
         FIG. 7   a  is a plot for the isotherm of the porous nickel hydroxide of Example 2; and 
         FIG. 7   b  is a plot for the pore size distribution of the porous nickel hydroxide of Example 2. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. 
     Manufacturing of Porous Materials 
     Synthesis methods capable of mass production are provided to synthesize the porous materials using the surfactants as the pore former. According to the present invention, the continuous process for manufacturing a porous material includes the steps of mixing a non-ionic surfactant with a precursor of the predetermined material to obtain a mixture and coating or depositing the mixture onto the flexible substrate in a roll to roll manner. Next, conversion is performed to obtain a composite sol. After removing the non-ionic surfactants and residue ions, the porous material is obtained. In addition, depending on the porous materials, a heating treatment may optionally be performed to conduct a dehydration or phase transformation after the drying step. 
     In a batch process, the concentration gradient of reactant is existed such that it is hard to control the uniformity of the conversion. According to embodiments of the invention, diffusion distances of reactant can be controlled with an adjustable film thickness in the converting step to achieve uniform conversions in the continuous mass production. 
       FIG. 1  is a flow chart showing an exemplary continuous process for manufacturing a porous material. As shown in  FIG. 1 , in a mixing step S 1 , raw materials such as at least one non-ionic surfactant and a precursor of a predetermined material are mixed to obtain a mixture. The mixture comprises a continuous phase and a liquid crystalline mesophase comprising the non-ionic surfactants. The precursor is essentially located in the continuous phase, wherein the mixture comprises two continuous phases, or a continuous liquid crystalline mesophase and a continuous non-liquid crystalline phase. 
     Preferably, the liquid crystalline mesophase is a smectic phase. More preferably, the liquid crystalline mesophase is a smectic hexagonal phase. A column of a smectic hexagonal phase has a diameter from about 2 nm to about 20 nm. 
     In a coating or depositing step S 2 , as shown in  FIG. 2 , the mixture is coated or deposited onto a flexible substrate (e.g., a substrate  200  as shown in  FIGS. 2   a ˜ 2   c ) during a continuous process (e.g., performed by a coater  202  as shown in  FIGS. 2   a ˜ 2   c ). The flexible substrate can be metal or polymer. After the coating or depositing step, the precursor of the predetermined material is located in the continuous phase comprising the non-ionic surfactants and can be converted to the predetermined material. Methods for the conversion way can be precipitation, hydrolysis, condensation, redox reaction, polymerization, crosslinking or combinations thereof. In the coating or depositing step S 2 , the mixture is coated or deposited onto the flexible substrate to obtain the film (e.g., a film  204 ) by casting, impregnation, spraying, dipping, gravure, doctor blade, slot, slit, curtain, reverse or transfer coating, or printing . 
     Conversion uniformity can be controlled by adjusting the film thickness and diffusion distance of reactant in a continuous process. Furthermore, when a base precursor or the mixture of a base and a fugitive acid is added into the mixture, the hydroxyl ion concentration can be controlled by heating or illuminating. Because a base precursor or the mixture of a base and a fugitive acid and precursor can be well mixed before the converting step, the conversion uniformity can be controlled both for a batch or a continuous process. 
     The predetermined material can be oxide or hydroxide, such as silicon dioxide, titanium dioxide, nickel hydroxide, nickel oxide, manganese oxide and combinations thereof. For example, if the predetermined material is silicon dioxide, tetraethoxysilane (TEOS) can be used as precursors. If the predetermined material is titanium dioxide, titanium salt, organotitanium complexes or titanium alkoxide can be used as precursors. If the predetermined material is nickel hydroxide or nickel oxide, nickel salts or organonickel complexes can be used as precursors. If the predetermined material is manganese oxide (MnO x ), organomanganese complexes, manganese salts such as potassium permanganate and manganese sulfate, or potassium permanganate and manganese acetate can be used as precursors. 
     The non-ionic surfactants can be block, graft or branch copolymers. In addition, the non-ionic surfactants can be selected from the group consisting of ethylene oxide (EO) copolymer, propylene oxide (PO) copolymer, butylene oxide copolymer, vinyl pyridine copolymer, vinyl pyrrolidone, epichlorohydrin copolymer, styrene copolymer, acrylic copolymer, and combinations thereof. Further, the non-ionic surfactants may include the polyoxyethylene alkylether, such as C x H 2x+1 EO y H, where x is not less than 12 and y is not less than  6 . 
     Preferably, the molecular weight of the non-ionic surfactant is between 500 and 20000. More preferably, the molecular weight of the non-ionic surfactant is between 600 and 10000. 
     Preferably, the non-ionic surfactants may have an HLB value from 5 to 24. More preferably, the non-ionic surfactants may have an HLB value from 10 to 14. 
     Precipitation refers to at least one kind of metal ions being converted to obtain the undissolvable material. For example, Co(OH) 2  can be obtained by reacting the cobalt salt with hydroxyl ions. The hydroxyl ions can be produced from a base, base precursor or the mixture of the base and the fugitive acid. For a base, hydroxyl ion concentrations can be increased by dissolving a base into an aqueous solution. For example, sodium hydroxide and potassium hydroxide are the commonly used base. For a base precursor or the mixture of a base and a fugitive acid, the hydroxyl ion concentration is gradually increased by heating or illuminating, and the reaction rate can be controlled when the base precursor or the mixture of the base and the fugitive acid is decomposed. The base precursor or the mixture of the base and the fugitive acid can be the nitrogen-containing compound, such as guanidine, urea, amine, imine or derivatives thereof. 
     As shown in  FIG. 1 , after the coating or depositing step S 2 , the flexible substrate is conveyed to the next station by a continuous roll-to-roll process (e.g., a process performed by a roll-to-roll type conveyer  222  shown in  FIGS. 2   a ,  2   b  and  2   c ). 
     After the mixture containing precursor and non-ionic surfactants are coated or deposited onto flexible substrate as shown in as  FIG. 2   a , a converting step S 3 , as shown in  FIG. 1 , is applied to convert the precursor to the predetermined material. In another embodiment, after the mixture is coated or deposited onto a flexible substrate (e.g. the substrate  200 ) to form a film (e.g. the film  204 ), a base, base precursor or the mixture of the base and the fugitive acid can be coated or deposited onto a flexible substrate. The method of coating or depositing can be a dipping, spraying (refer to the sprayer  206  in  FIG. 2   b ), coating (refer to the coater  208  in  FIG. 2   c ), attaching, casting, impregnation, gravure, doctor blade, slot, slit, curtain, reverse, or printing, thereby obtaining the predetermined materials. When a base precursor or the mixture of the base and the fugitive acid is used as a reactant, a heating or illuminating treatment step (not shown) is required in the converting step S 3  to obtain the predetermined material. 
     As shown in  FIG. 2   a , the base precursor or the mixture of the base and the fugitive acid as a reactant, can be mixed in the mixture obtained at the step S 1 . 
     As shown in  FIG. 1 , after the converting step S 3 , a removing step S 4  is performed to remove the non-ionic surfactants and residue ions in the composite sol over the flexible substrate, wherein the composite sol contains the predetermined material, non-ionic surfactants and residue ions. After removing the non-ionic surfactants and residue ions, porous materials are obtained. In preferred embodiments, water or suitable solvents can be used for removing the non-ionic surfactants and residue ions. In the removing step S 4 , a spray washing (e.g. by a sprayer  310 ) can be directly performed on the substrate to obtain the porous material as shown in  FIG. 3   a . After the removing step S 4 , the porous materials are dried (e.g. by a dryer  312 ), scraped (e.g. by a scraper  314 ) and collected. In another embodiment, after the converting step S 3 , the composite sol is scraped (e.g. by a scraper  314 ) into a washing tank (e.g. by a tank  316 ) to remove non-ionic surfactants and residue ions, as shown in  FIG. 3   b.    
     As shown in  FIG. 1 , after removing non-ionic surfactants and residue ions in step S 4 , a drying step S 5  is then performed by a spray drying, freeze drying, or continuous tunnel drying or by using a batch oven to remove the solvent or the water, as shown in  FIGS. 3   a  and  3   b.    
     As shown in  FIG. 1 , a heating treatment S 6  may optionally be performed after the drying step S 5  to conduct a dehydration or phase transformation. For example, the TiO 2  crystalline phase can be changed from anatase to rutile after a heating treatment. 
     The process of the invention can be synthesized by using the surfactants as the pore former and is not limited to only synthesizing the specific materials, porous metal oxide, hydroxides, or the like. 
     In the preferred embodiment of the invention, tetraethoxysilane (TEOS) is used as the precursor to be incorporated with a non-ionic surfactant, such as P123 (a triblock copolymer produced by BASF® Corp.) or C 16 H 33 EO 10 H for obtaining SiO 2  by using a sol-gel method. After removal of P123 or C 16 H 33 EO 10 H, porous SiO 2 . A titanium salt or organotitainium complex, such as titanium alkyoxide, can be used as precursors for obtaining TiO 2 . For example, titanium isopropoxide or titanium butoxide is mixed with non-ionic surfactants and then coated or deposited onto a flexible substrate. After a converting step, a removing step is performed to remove the non-ionic surfactants to obtain the porous TiO 2 . 
     In order to enhance conductivity of the predetermined material, an additive can be added into the mixture. The additive can be metal salt or a conductive agent. For example, cobalt salt or organocobalt complexes can be added into the mixture of the nickel salt or organonickel complexes, C 16 H 33 EO 10 H or P123 surfactants. After the converting and removing steps, the porous material of the cobalt-doped nickel hydroxide can be obtained. In another embodiment, the conductive agent, such as graphite, graphene, carbon black, carbon nanotube (CNT) or metal particles which comprises Ti, Pt, Ag, Au, Al, Ru, Fe, V, Ce, Zn, Sn, Si, W, Ni, Co, Mn, In, Os, Cu, or Nb can be added into the mixture. The precursor is converted to the predetermined material, and then a removing step is performed to obtain the composite with porous structure. 
     Preferably, the manufacturing process further includes the steps of adding a swelling agent into the mixture, wherein the swelling agent is selected from the group consisting of 1,3,5-trimethylbenzene (TMB), cholesterol, polystyrene, polyethers, polyetheramines, polyacrylate, polyacrylic and derivatives thereof. 
     Manufacturing Electrodes with Porous Materials 
     For the manufacturing of an electrode, a metal substrate made of nickel, copper, or aluminum can be applied. Without scraping the composite sol from the metal substrate, the porous materials can be obtained on the metal substrate after the removing step of the non-ionic surfactants and residue ions and the drying step. Electrodes comprising porous materials can be manufactured by using an adequate cutting step (e.g. by the cutter  318  shown in  FIG. 4 ) in a continuous process. The electrodes can be applied to batteries, super capacitors or fuel cells. 
     In order to enhance conductivity of predetermined material, an additive can be added into a mixture. The additive can be metal salt or a conductive agent. For example, the nickel salt or organonickel complexes, C 16 H 33 EO 10 H or P123 surfactants and cobalt salt or organocobalt complexes are mixed to obtain a mixture and coated or deposited onto a metal substrate. After the converting and removing steps, the porous material of the cobalt doped nickel hydroxide on the metal substrate can be obtained. In another embodiment, the conductive agent, such as graphite, graphene, carbon black, carbon nanotube (CNT) or metal particles which comprises Ti, Pt, Ag, Au, Al, Ru, Fe, V, Ce, Zn, Sn, Si, W, Ni, Co, Mn, In, Os, Cu, or Nb can be added into the mixture. The mixture is converted to the composite sol. After a step of removing the non-ionic surfactants and residue ions and a step of drying, electrodes with porous material can be obtained by an adequate cutting step. 
     Manufacturing Electrodes with Porous Materials Containing Silver Particles 
     In order to increase the conductivity of predetermined materials, silver halide, such as silver chloride, silver bromide, and silver iodide, and a developing agent or reducing agent can be added into the mixture. During manufacturing of the electrodes, silver halide is reduced to silver particles in the porous materials. Under illumination (e.g. by the illumination device  520  shown in  FIG. 5   a ), few silver ions will be reduced to silver atoms as the nuclei. In the existence of silver atoms, a developing agent or reducing agent can be used to reduce the residue silver ions to silver particles. Typically, the developing agent or reducing agent is an organic compound including hydroquinone, aminophenol, phenylene-diamine, derivatives thereof, and combinations thereof. Preferably, the developing agent or reducing agent can be methyl p-aminophenol, N-methyl-p-aminophenol salt, 1-phenyl-3-pyrazolidinone, derivatives thereof, and combinations thereof. 
     In another embodiment, as shown in  FIGS. 5   a - 5   b,  silver halide, such as silver chloride, silver bromide, and silver iodide, and a developing agent or reducing agent can be added into the mixture. A coating or depositing step is performed after the mixing step. Before the converting step, silver halide is reduced to silver particles by reacting with the developing agent or reducing agent under illumination (e.g. by illumination device  520  shown in  FIGS. 5   a  and  5   b ). A base is coated or deposited (e.g. by the sprayer  206  or the coater  208  shown in  FIGS. 5   a  and  5   b , respectively) onto a flexible substrate to convert the precursor to Ni(OH) 2 . The residue silver ions can be further reduced to silver particles under the basic condition. After the removing step (e.g. by a sprayer  310  as shown in  FIG. 5   c ) and drying step (e.g. by a dryer  312  as shown in  FIG. 5   c ), a porous Ni(OH) 2  containing silver particles is obtained as shown in  FIGS. 5   c . In another embodiment shown in FIG.  5   d,  the composite sol is scraped (e.g. by a scraper  314 ) into a washing tank (e.g. by a tank  316 ) to remove non-ionic surfactants and residue ions. Then the porous Ni(OH) 2  containing silver particles is obtained after a drying step. 
     In another embodiment of the invention, silver halide, such as silver chloride, silver bromide, and silver iodide, and a developing agent or reducing agent can be added into the mixture. The mixture is coated or deposited onto a metal substrate. The metal substrate can be nickel, copper, or aluminum. After the converting step, the composite sol is not scraped from the metal substrate. Electrodes with porous Ni(OH) 2  containing silver particles can be obtained by a removing step and a cutting step (e.g. by a cutting  318  as shown in  FIG. 5   e ). The electrodes can be applied to batteries, super capacitors or fuel cells. 
     The present invention provides two exemplary embodiments of the manufacturing of porous nickel hydroxide as follows. 
     EXAMPLE 1 
     A surfactant C 16 H 33 EO 10 H, methanol, and nickel chloride are mixed in water to form a mixture. The content of C 16 H 33 EO 10 H in the mixture is 60 wt. %. The mixture is deposited onto substrate to form a film with thickness of 4 mm. The converting step is conducted by spraying a NaOH solution under 25° C. to obtain a Ni(OH) 2  composite sol. After washing by water and ethanol, a drying step is performed at 60° C. to obtain a porous nickel hydroxide. As shown in  FIG. 6   a , the isotherm plot of the nickel hydroxide exhibits a capillary condensation step at relative pressure from 0.4 to 0.8 and exhibits the pores structure in the nickel hydroxide As shown in  FIG. 6   b , the pore size distribution of the porous nickel hydroxide is narrow and the specific surface area and pore diameter of the porous nickel hydroxide are 525.0 m 2 /g and approximately 6.1 nm, respectively. 
     EXAMPLE 2 
     A surfactant C 16 H 33 EO 10 H, urea, and nickel chloride are mixed in water to form a mixture. The content of C 16 H 33 EO 10 H in the mixture is 60 wt. %. The converting step is conducted by heating at 65° C. to obtain a Ni(OH) 2  composite sol. After washing by water and ethanol, a drying step is performed at 60° C. to obtain a porous nickel hydroxide.  FIG. 7   a  shows the isotherm of the porous nickel hydroxide of Example 2. As shown in  FIG. 7   a , the isotherm plot of the nickel hydroxide exhibits a capillary condensation step at relative pressure from 0.4 to 0.8 and exhibits the pores structure in the nickel hydroxide. As shown in  FIG. 7   b , the pore size distribution of the porous nickel hydroxide is narrow and the specific surface area and pore diameter of the porous nickel hydroxide are 285.5 m 2 /g and approximately 3.8 nm, respectively. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.