Abstract:
An amorphous carbon material for lithium-ion secondary battery negative electrode is capable of reducing capacity degradation due to repeated charge and discharge cycles, storage while being charged, or floating charge.A method for producing an amorphous carbon material for a negative electrode of a lithium-ion secondary battery includes the steps of: pulverizing and classifying a raw coke composition obtained from a heavy-oil composition undergone coking by delayed coking process to obtain powder of the raw coke composition, the raw coke composition having a H/C atomic ratio that is a ratio of hydrogen atoms H and carbon atoms C of 0.30 to 0.50 and having a micro-strength of 7 to 17 mass %; giving compressive stress and shear stress to the powder of the raw coke composition to obtain a carbonized composition precursor; and heating the carbonized composition precursor under an inert atmosphere at a temperature from 900° C. to 1,500° C. so that a size of a crystallite Lc(002) is in a range of 2 nm to 8 nm, the size being calculated from a (002) diffraction line obtained by X-ray wide-angle diffractometry.
Abstract:
An amorphous carbon material for lithium-ion secondary battery negative electrode is capable of reducing capacity degradation due to repeated charge and discharge cycles, storage while being charged, or floating charge.A method for producing an amorphous carbon material for a negative electrode of a lithium-ion secondary battery includes the steps of: pulverizing and classifying a raw coke composition obtained from a heavy-oil composition undergone coking by delayed coking process to obtain powder of the raw coke composition, the raw coke composition having a H/C atomic ratio that is a ratio of hydrogen atoms H and carbon atoms C of 0.30 to 0.50 and having a micro-strength of 7 to 17 mass %; giving compressive stress and shear stress to the powder of the raw coke composition to obtain a carbonized composition precursor; and heating the carbonized composition precursor under an inert atmosphere at a temperature from 900° C. to 1,500° C. so that a size of a crystallite Lc(002) is in a range of 2 nm to 8 nm, the size being calculated from a (002) diffraction line obtained by X-ray wide-angle diffractometry.
Abstract:
The present invention relates to carbon nanotubes that are excellent in dispersibility and a process for producing the carbon nanotubes. The carbon nanotubes according to the present invention each comprise a wall that comprises a parallel portion and a narrowed portion having a tube outer diameter that is not more than 90% of a tube outer diameter of the parallel portion. Thus, the carbon nanotubes are readily dispersible owing to a high abundance ratio of easily-breaking portions.