Hardly graphitizable carbonaceous material for nonaqueous electrolyte secondary batteries fully charged to be used, method for producing same, negative electrode material for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery fully charged to be used

Abstract

To provide a hardly graphitizable carbonaceous material used in a negative electrode material for nonaqueous electrolyte secondary batteries (for example, a lithium ion battery) having not only high charge capacity but also high charge-discharge efficiency and being fully charged to be used and a method for producing the same. To provide a negative electrode material for nonaqueous electrolyte secondary batteries comprising such a hardly graphitizable carbonaceous material, and a nonaqueous electrolyte secondary battery comprising such a negative electrode material for nonaqueous electrolyte secondary batteries and being fully charged to be used. A hardly graphitizable carbonaceous material, being a hardly graphitizable carbonaceous material for nonaqueous electrolyte secondary batteries fully charged to be used and having an oxygen element content of 0.25% by mass or less.

1 : A hardly graphitizable carbonaceous material, having an oxygen element content of 0.25% by mass or less. 
     
     
         2 : The hardly graphitizable carbonaceous material according to  claim 1 , wherein, when taken out of a nonaqueous electrolyte secondary battery in a fully charged state, a main resonance peak position of a chemical shift value observed by  7 Li nuclear-solid state NMR analysis is downfield by more than 115 ppm from a peak position of lithium chloride. 
     
     
         3 : The hardly graphitizable carbonaceous material according to  claim 1 , which is derived from a carbon precursor originating from a plant. 
     
     
         4 : The hardly graphitizable carbonaceous material according to  claim 1 , further having an average face-to-face dimension d 002  of the (002) face calculated from the Bragg equation by a wide angle X-ray diffraction method of 0.36 to 0.42 nm. 
     
     
         5 : The hardly graphitizable carbonaceous material according to  claim 1 , further having a specific surface area determined by a nitrogen adsorption BET three-point method of 1 to 20 m 2 /g. 
     
     
         6 : The hardly graphitizable carbonaceous material according to  claim 1 , further having a true density determined by a butanol method of 1.40 to 1.70 g/cm 3 . 
     
     
         7 : The hardly graphitizable carbonaceous material according to  claim 1 , further having a potassium element content of 0.1% by mass or less and an iron element content of 0.02% by mass or less. 
     
     
         8 : A method for producing the hardly graphitizable carbonaceous material according to  claim 1 , comprising:
 subjecting a carbon precursor to an acid treatment; and   calcining an acid-treated carbon precursor under an inert gas atmosphere at a temperature of 1100° C. to 1400° C.   
     
     
         9 : A negative electrode material suitable for nonaqueous electrolyte secondary batteries, comprising the hardly graphitizable carbonaceous material according to  claim 1 . 
     
     
         10 : A nonaqueous electrolyte secondary battery, which comprises a negative electrode material comprising a hardly graphitizable carbonaceous material and which is fully charged to be used,
 wherein the hardly graphitizable carbonaceous material has an oxygen element content of 0.25% by mass or less.   
     
     
         11 : The nonaqueous electrolyte secondary battery according to  claim 10 , wherein a main resonance peak position of a chemical shift value of the hardly graphitizable carbonaceous material observed by  7 Li nuclear-solid state NMR analysis is downfield by more than 115 ppm from a peak position of lithium chloride. 
     
     
         12 : The nonaqueous electrolyte secondary battery according to  claim 10 , wherein the hardly graphitizable carbonaceous material is derived from a carbon precursor originating from a plant. 
     
     
         13 : The nonaqueous electrolyte secondary battery according to  claim 10 , wherein the hardly graphitizable carbonaceous material has an average face-to-face dimension d 002  of the (002) face calculated from the Bragg equation by a wide angle X-ray diffraction method of 0.36 to 0.42 nm. 
     
     
         14 : The nonaqueous electrolyte secondary battery according to  claim 10 , wherein the hardly graphitizable carbonaceous material has a specific surface area determined by a nitrogen adsorption BET three-point method of 1 to 20 m 2 /g. 
     
     
         15 : The nonaqueous electrolyte secondary battery according to  claim 10 , wherein the hardly graphitizable carbonaceous material has a true density determined by a butanol method of 1.40 to 1.70 g/cm 3 . 
     
     
         16 : The nonaqueous electrolyte secondary battery according to  claim 10 , wherein the hardly graphitizable carbonaceous material has a potassium element content of 0.1% by mass or less and an iron element content of 0.02% by mass or less.