Developing new earth-abundant materials has been attracted more and more attention for energy storage applications. In this talk, I would like to talk about our recent work related to development of Aluminum ion battery (AIB). AIB was demonstrated recently based on Al foil anode, graphite cathode and ionic liquid electrolyte. Much remains to be done to increase the cathode capacity and to understand details of the anion-graphite intercalation mechanism. Here, we developed a freestanding film of natural graphite flakes bound by a binder as AIB cathode. The specific capacity and Coulombic efficiency of the battery was achieved ~110 mAh/g and ~98% respectively, at a current density of 99 mA-g-1 with clear discharge voltage plateaus ~2V. The cycle stability of the battery exceeded 6000 cycles with a capacity of 60 mAh/g at a current density of 660 mA/g. Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy data elucidated chloroaluminate intercalation in natural graphite. Finally, theoretical calculations were employed to investigate the intercalation behavior of choloraluminate anions in the graphite electrode.