Lithium secondary battery and conductive assistant used in same

Abstract

A lithium secondary battery, including: a hydrofluoric acid-containing electrolytic solution; an electrode; and a conductive assistant, in which the conductive assistant (1) contains a substance that is poorly soluble in the hydrofluoric acid-containing electrolytic solution, the substance including one or more kinds selected from transition metal compounds, and (2) contains a substance that is soluble in the hydrofluoric acid-containing electrolytic solution, the substance having a total metal mass of 0 mass % or more and 0.003 mass % or less with respect to a total mass of the electrode; and a conductive assistant, including: a substance that is poorly soluble in a hydrofluoric acid-containing electrolytic solution; and a substance that consumes hydrofluoric acid, the conductive assistant being substantially free, or including 1 mass % or less with respect to a total mass thereof, of a substance that is soluble in the hydrofluoric acid-containing electrolytic solution.

What is claimed is: 
     
         1 . A fibrous carbon material, comprising:
 substance A that is poorly soluble in a hydrofluoric acid-containing electrolytic solution, the substance A comprising one or more compounds selected from the group consisting of transition metal compounds,   the fibrous carbon material being substantially free, or including 1 mass % or less with respect to a total mass thereof, of substance B that is soluble in the hydrofluoric acid-containing electrolytic solution.   
     
     
         2 . The fibrous carbon material according to  claim 1 , in which the substance A is at least one compound selected from the group consisting of iron (II) oxide, iron(III) oxide, and triiron carbide. 
     
     
         3 . The fibrous carbon material according to  claim 1 , which further contains substance C that consumes hydrofluoric acid. 
     
     
         4 . The fibrous carbon material according to  claim 3 , in which a content of the substance C is 2 mass % or more and 20 mass % or less with respect to a total mass of the fibrous carbon material. 
     
     
         5 . The fibrous carbon material according to  claim 3 , in which the substance C is a metal oxide. 
     
     
         6 . The fibrous carbon material according to  claim 3 , in which the substance C is intermediate alumina. 
     
     
         7 . The fibrous carbon material according to  claim 1 , which comprises metal-encapsulating carbon nanotubes, and in which the substance A is present outside the carbon nanotubes.