NOVELTY - The carbon-based negative electrode material which is formed as a porous graphite (102) is provided with a graphene layer structure. The carbon-based negative electrode material is also provided with crystallinity and pores. The diameters of the pores range from 2 nm to 4 nm.    USE - Carbon-based negative electrode material for use with electrolyte containing propylene carbonate in negative electrode of secondary battery (all claimed) such as coin secondary battery used as power storage device or power supply of variety of electric appliances such as display devices, lighting devices, electronic-book (e-book) readers, desktop personal computers, laptop personal computers, image reproduction devices, mobile phones, portable game machines, video cameras as well as used in electric vehicles, hybrid vehicles and motorized bicycles. Can also be used in high-frequency heating appliances such as microwave ovens, electric rice cookers, electric washing machines, air-conditioning systems such as air conditioners, electric refrigerators, electric freezers, electric refrigerator-freezers, freezers for preserving DNA, and dialyzers.    ADVANTAGE - The impurities can be removed to give a residue of the graphite oxide. Pure water is added to the resulting residue of the graphite oxide to yield a suspension and the obtained suspension is centrifuged to give a precipitate. The supernatant fluid is removed because it contains a large amount of hydrochloric acid, so that unnecessary ions and the like other than graphite oxide can be removed in an efficient manner. The distance between the graphenes is so large that the graphenes can be prevented from being separated from each other even when solvated lithium ions penetrate the porous graphite. Since the distance between graphenes in the porous graphite is larger than the size of the solvated lithium ion, the graphenes can be prevented from being separated from each other. Thus, the porous graphite can be used in an electrolyte containing PC as a main ingredient.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for secondary battery.    DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional view of the negative electrode of secondary battery.    Current collector (100)    Porous graphite (102)    Electrolyte (103)