System And Method For Forming Activated Carbon Aerogels And Performing 3D Printing

Abstract

Making a carbon aerogel involves 3-D printing an ink to make a printed part, removing the solvent from the printed part, and carbonizing the printed part (with the solvent removed) to make the aerogel. The ink is based on a solution of a resorcinol-formaldehyde resin (RF resin), water, and an organic thickener. Advantageously, the RF resin contains an acid catalyst, which tends to produce carbon aerogels with higher surface areas upon activation than those produced from methods involving an ink composition containing a base catalyzed resin.

What is claimed is: 
     
         1 . A method of forming a carbon aerogel, comprising
 3-D printing an ink to make a printed part, wherein the ink comprises solvent, a resorcinol-formaldehyde resin, and an organic thickener;   removing the solvent from the printed part; and   carbonizing the printed part to make the aerogel,   wherein the resorcinol-formaldehyde resin comprises an acid catalyst and has a formaldehyde:resorcinol molar ratio greater than 1:1,   wherein the thickener is soluble in water, is made of only C, H, and O atoms, and contains only ether or alcohol functional groups.   
     
     
         2 . The method of  claim 1 , wherein the ink further comprises a thixotropic agent. 
     
     
         3 . The method of  claim 2 , wherein the thixotropic agent comprises fumed silica and the method further comprises HF etching to remove silica from the printed part. 
     
     
         4 . The method of  claim 1 , wherein the organic thickener comprises a soluble cellulose derivative or a soluble polyoxyalkylene compound. 
     
     
         5 . The method of  claim 1 , wherein the acid catalyst comprises acetic acid. 
     
     
         6 . The method of  claim 1 , wherein the ink further comprises graphene oxide. 
     
     
         7 . The method of  claim 1 , wherein the ink is free of graphene oxide. 
     
     
         8 . A carbon aerogel made by the method of  claim 1 . 
     
     
         9 . A 3-D printing ink, comprising:
 a solvent comprising water;   an organic thickener;   resorcinol and formaldehyde; and   an acid catalyst that catalyzes a reaction between the resorcinol and formaldehyde,   wherein the thickener is soluble in water, is made of only C, H, and O atoms, and contains only ether or alcohol functional groups.   
     
     
         10 . The ink of  claim 9 , further comprising a thixotropic additive. 
     
     
         11 . The ink of  claim 10 , wherein the thixotropic additive comprises fumed silica. 
     
     
         12 . The ink of  claim 9 , wherein the acid catalyst comprises acetic acid. 
     
     
         13 . The ink of  claim 9 , wherein the molar ratio of resorcinol to formaldehyde is less than 1:1. 
     
     
         14 . The ink of  claim 9 , further comprising graphene oxide. 
     
     
         15 . The ink of  claim 9 , wherein the thickener comprises hydroxypropylmethylcellulose. 
     
     
         16 . The ink of  claim 9 , wherein the thickener comprises a polyoxyalkylene compound. 
     
     
         17 . The ink of  claim 9 , comprising 10% to 60% by weight of the resin. 
     
     
         18 . A supercapacitor comprising a positive electrode, a negative electrode, and a separator disposed between the electrodes, wherein at least one of the positive electrode, negative electrode, and separator comprises a carbon aerogel according to  claim 7 . 
     
     
         19 . The supercapacitor of  claim 18 , characterized by a specific capacitance greater than 240 F/g.