Studies on capacity fading mechanism of graphite anode for Li-ion battery

It is of great importance to improve the electrochemical performance of graphitic anode materials since they are dominantly used in practical lithium ion battery and still will be the main component as anode material in the future. By SEM, XPS, Micro-Raman and EDX analyses of graphite electrodes before and after discharge/charge cycle, it is found that capacity fading is strongly related to the dispersion of conductive. Homogeneous dispersion of conductive resulted in good cycle performance. However, for the poorly fabricated electrode, with heterogeneous dispersion of conductive, it gives rise to the formation of imperfect SEI film in the first cycle and subsequent continual decomposition of the electrolyte, leading to large amounts of nonconductive surface deposits consisting of Li₂CO₃ and LiF. As a result, its irreversible capacity is high and capacity retention is poor. Thus, homogeneous dispersion of conductive is necessary to obtain good performance for graphitic anode electrode. The formation of Li₂CO₃ and LiF during repeated cycling is attributed to the inhomogeneous distribution of the overpotential throughout the fabricated electrode.