Abstract: The SEI (solid electrolyte interphase) film on the surface of three kinds of carbonous materials:
Mesocarbon Microbead (MCMB); Porous Carbon (PC) and Synthetic Graphite (SG), which can electrochemically insert and extract lithium reversibly,
was investigated in the appointed electrolyte. The formation of SEI is related to the structure and BET surface of the carbonous materials. This
causes the main irreversible capacity of carbonous electrode at the first charge and discharge cycle. It will play an active role for the cycle
stability after the first charge and discharge cycle when the stable film is forming on the surface of the electrode.

Key words: SEI film, electfochemical characteristic, carbonous anode, lithium ion batteries