Electrochemical performance of a novel surface modified spherical graphite as anode material for lithium ion batteries

摘要

We prepared a new anode material, SSG (special spherical graphite), for lithium ion batteries by reforming natural graphite into spherical shape, and two coatings with polymers on its surface followed by heat-treatment in inert atmosphere after each coating step. The dispersion of conductive additive markedly influenced the cycling behavior. With good dispersion the cycling performance was excellent. The initial reversible capacity was 348 mAh g~(-1) at a rate of about 2C, greater than that of commercial synthetic graphite, and remained at 86.5 percent after 500 cycles in a cell with lithium metal as counter and reference electrodes. With poor dispersion numerous white deposits were produced; lower reversible capacity and rapid capacity fade were observed. At low rate (0.08C) the charge curve showed evidence of a staging phenomenon.