High performance nano/micro composite fiber capable of storing electrical energy and method for fabricating thereof

Abstract

Provided a nano/micro composite fiber of the present invention, capable of storing electrical energy, comprising (a) one or more pairs of microfiber bundles consisting of graphene or graphene/carbon nanotube as an electrode active material; (b) nanofiber web surrounding the microfiber bundles, wherein the nanofiber web is coated by one or more materials selected from the group consisting of metal, carbon nanotube, activated carbon and metal oxide nanoparticle; (c) an electrolyte layer surrounding the nanofiber web and filling inner void of the microfibers and nanofiber web; (d) an insulating film sheathing the electrolyte layer.

1 . A nano/micro composite fiber capable of storing electrical energy, comprising:
 (a) one or more pairs of microfiber bundles consisting of graphene or graphene/carbon nanotube as an electrode active material;   (b) nanofiber web surrounding the microfiber bundles, wherein the nanofiber web is coated by one or more materials selected from the group consisting of metal, carbon nanotube, activated carbon and metal oxide nanoparticle;   (c) an electrolyte layer surrounding the nanofiber web and filling inner voids of the microfibers and nanofiber web;   (d) an insulating film sheathing the electrolyte layer.   
     
     
         2 . The composite fiber of  claim 1 , wherein the graphene is a reduced graphene oxide. 
     
     
         3 . The composite fiber of  claim 1 , wherein the graphene has an acid group at the edge or on the surface thereof. 
     
     
         4 . The composite fiber of  claim 3 , wherein the acid group is a carboxyl group (—COOH). 
     
     
         5 . The composite fiber of  claim 1 , wherein the carbon nanotube has a sulfonic acid group (SO 3   − ) on the surface thereof. 
     
     
         6 . The composite fiber of  claim 1 , wherein the graphene or graphene/carbon nanotube microfibers are modified by heating at a temperature between 60° C. and 100° C. under a strong acid. 
     
     
         7 . The composite fiber of  claim 6 , wherein the strong acid is selected from sulfuric acid, nitric acid, hydrochloric acid, or a mixed acid thereof. 
     
     
         8 . The composite fiber of  claim 6 , wherein the heating is performed at a temperature between 80° C. and 85° C. 
     
     
         9 . The composite fiber of  claim 1 , wherein the material of the nanofiber is one or more selected from the group consisting of polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polymethyl methacrylate (PMMA), polymethacrylic acid (PMAA), polyacrylic acid (PAA), polyvinyl chloride, Polylactic acid (PLA), polycaprolactone (PCL), polyurethane (PU), polystyrene (PS), polyethylene oxide (PEO), polyvinyl acetate (PVAC), polyacrylonitrile (PAN), nylon, polyetherimide (PC), polyetherimide (PEI), polyester (PET), polyester sulfone (PES) and polybenzimidazole (PBI). 
     
     
         10 . The composite fiber of  claim 1 , wherein the metal of the nanofiber web is one or more selected from the group consisting of aluminum, copper, silver, gold, chromium, nickel, platinum, titanium and an alloy thereof. 
     
     
         11 . The composite fiber of  claim 1 , wherein the metal oxide nanoparticle of the nanofiber web is one or more selected from the group consisting of manganese dioxide (MnO 2 ), rubidium dioxide (RuO 2 ), and gadolinium oxide (Gd 2 O 3 ). 
     
     
         12 . The composite fiber of  claim 1 , wherein the first and/or second electrolyte is selected from a gel electrolyte, a solid electrolyte, a polymer electrolyte, a liquid electrolyte. 
     
     
         13 . A method for fabricating a nano/micro composite fiber capable of storing electrical energy, comprising the steps of
 (a) wet spinning an aqueous dispersion of graphene or graphene/carbon nanotube to prepare a microfiber;   (b) bundling the microfibers to prepare microfiber bundle;   (c) wrapping the microfiber bundle with a nanofiber web to prepare a nano/micro composite fiber, wherein the nanofiber web is coated with one or more materials selected from the group consisting of metal, carbon nanotube, activated carbon, and metal oxide nanoparticle;   (d) impregnating the nano/micro composite fiber with an electrolyte to form an electrolyte layer;   (e) twisting one or more pairs of electrolyte-coated nano/micro composite fibers;   (f) sheathing the electrolyte-coated nano/micro composite fiber with insulating material.   
     
     
         14 . The method of  claim 13 , wherein, after the step (a), (b) or (c), further comprising the step of heating the microfiber at a temperature between 60° C. and 100° C. under a strong acid to modify the surface of microfibers. 
     
     
         15 . The method of  claim 14 , wherein the strong acid is selected from sulfuric acid, nitric acid or hydrochloric acid. 
     
     
         16 . The method of  claim 14 , wherein the heating is performed at a temperature between 80° C. and 85° C. 
     
     
         17 . The method of  claim 13 , wherein further comprising the step of impregnating one or more pairs of the electrolyte-coated nano/micro composite fibers with an electrolyte to form a second electrolyte later. 
     
     
         18 . The method of  claim 13 , at the step (c) and/or (d) further performing electrophoreses to penetrate the electrolyte into the voids of the nano/micro composite fiber by using electrophoresis method.