Fine carbon fiber and method for producing the same

Abstract

A vapor grown fine carbon fiber including a hollow space along the fiber in its interior, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 10 to 15,000 is disclosed. The fiber has a center portion and a peripheral portion, and the center portion having a carbon structure different from that of the peripheral portion. A method for producing the fine carbon fiber, and a battery and gas occlusion material containing the fine carbon fiber are also disclosed.

What is claimed is:  
     
         1 . A method for producing a fine carbon fiber comprising thermally decomposing a carbon material in the presence of a catalyst fluid containing a solvent and fine particles of a catalyst dispersed therein, wherein the fine particles have a size of 20 nm or less, and the catalyst comprises a transition metallic compound comprising at least one element selected from the group consisting of Fe, Ni, and Co.  
     
     
         2 . The method according to  claim 1 , wherein the fine particles are dispersed in an organic dispersant by a dispersant or a surfactant, and the transition metal compound is dispersed in an amount of 0.003 to 5 mass %.  
     
     
         3 . The method according to  claim 2 , wherein the surfactant is a cationic or anionic surfactant.  
     
     
         4 . The method according to  claim 1 , wherein a sulfur compound is employed as a promoter in an amount of 0.01 to 10 mass %.  
     
     
         5 . The method according to  claim 1 , wherein the transition metal compound is dispersed in a carbon material serving as a carbon source, and the resultant mixture is sprayed in the form of a liquid into a reaction furnace by use of a carrier gas.  
     
     
         6 . The method according to  claim 1 , wherein the catalyst particles have a particle size of 200 nm or less.  
     
     
         7 . The method according to  claim 1 , wherein the catalyst fine particles are Fe 3 O 4  fine particles prepared in a reversed micelle containing water/bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT)/benzene.