AMORPHOUS CARBON MATERIAL FOR LITHIUM ION SECONDARY BATTERY NEGATIVE ELECTRODE AND NONAQUEOUS SECONDARY BATTERY USING SAME

摘要

Provided is an amorphous carbon material for a lithium ion secondary battery negative electrode that can suppress capacity deterioration due to repetition of charge/discharge cycle, storage in a charged state, floating charge, and the like. A nonaqueous electrolyte secondary battery includes: a positive electrode including lithium that is capable of reversible intercalation of lithium; a negative electrode made of an amorphous carbon material; and nonaqueous electrolyte. In the negative electrode, the size of crystallite Lc (002) in c axis direction calculated from (002) diffraction line of an amorphous carbon material measured by a powder X-ray diffraction method is 2.0 to 8.0 nm. The negative electrode has a carbon-derived spectrum that appears in the range between 3200 and 3400 gauss (G) in an electron spin resonance technique measured with the use of X band. Further, the followings are satisfied: a relative signal strength ratio (I4.8K/I40k) of a signal strength at the temperature 4.8K (I4.8K) to a signal strength of the spectrum measured at the temperature 40K (I40K) is 2.4 to 3.5; and a line width of the spectrum (?Hpp) calculated from a first derivation spectrum at the temperature 4.8K is 70 to 180 gauss (G).