Non-aqueous secondary battery having negative electrode including graphite powder

Abstract

Objects of the present invention is to provide a carbon material having a superior reversibility in lithium intercalation-deintercalation reaction, and a non-aqueous secondary battery using the carbon material as an active material for a negative electrode, which has a high energy density and an excellent rapid charging and discharging characteristics. Graphite powder having a maximum particle diameter of less than 100 μm and an existing fraction of rhombohedral structure in the crystalline structure of less than 20% is used as an active material for the negative electrode of the non-aqueous secondary battery. The graphite powder can be obtained by pulverizing raw graphite with a jet mill, and subsequently treating the powder at a temperature equal to or higher than 900° C.

1 . Electrodes for a non-aqueous secondary battery, comprising: 
 a positive electrode, and    a negative electrode,    said positive electrode or said negative electrode intercalating and deintercalating ions, wherein    said negative electrode comprises graphite powder having a crystal structure, the crystal structure including a hexagonal crystal structure fraction and a rhombohedral crystal structure fraction, and a particle size of the graphite powder is equal to or smaller than 100 μm, as an active material, and    the hexagonal crystal structure fraction in the crystal structure of said graphite powder is at least 80% by weight.    
     
     
         2 . Electrodes for a non-aqueous secondary battery, comprising: 
 a positive electrode, and    a negative electrode,    said positive electrode or said negative electrode intercalating and deintercalating ions, wherein    an active material of said negative electrode is carbon material,    said carbon material is composed of graphite powder having crystal structure,    said graphite powder has a particle size equal to or smaller than 100 μm, and    a fraction of a hexagonal crystal structure in the crystal structure of said graphite powder is at least 80% by weight.    
     
     
         3 . Electrodes according to  claim 2 , wherein the graphite powder has substantially completely the graphite structure.  
     
     
         4 . Electrodes for a non-aqueous secondary battery, comprising: 
 a positive electrode, and    a negative electrode,    said positive electrode or said negative electrode intercalating and deintercalating ions, wherein    an active material of said negative electrode is carbon material,    said carbon material is composed of natural graphite powder having a crystal structure and having a particle size equal to or smaller than 100 μm, and    an existing fraction of a hexagonal crystal structure in the crystal structure of said natural graphite powder is at least 80% by weight.    
     
     
         5 . Electrodes for a non-aqueous secondary battery, comprising: 
 a positive electrode, and    a negative electrode,    said positive electrode or said negative electrode intercalating and deintercalating ions, wherein    said negative electrode comprises carbon material as an active material,    said carbon material is composed of graphite powder having a crystal structure,    said graphite powder has a particle size equal to or smaller than 100 μm,    an existing fraction of hexagonal crystal structure in the crystal structure of said graphite powder is at least 80% by weight, and    said graphite powder has a deintercalating capacity for lithium of at least 320 mAh/g.