Pitch-based ultrafine carbon fibers, method for producing same, non-aqueous electrolyte secondary battery negative electrode using said pitch-based ultrafine carbon fibers, and non-aqueous electrolyte secondary battery having said non-aqueous electrolyte secondary battery negative electrode

摘要

The present invention provides pitch-based ultrafine carbon fibers that have an average fiber diameter of at least 100 nm and less than 700 nm, and an average fiber length of 10 μm or more, wherein C—O bonds >C═O bonds in terms of the abundance ratio (molar ratio) of C—O bonds and C═O bonds derived from the O1s orbital as measured by X-ray photoelectron spectroscopy.