A cell employing a graphite cathode and a molybdenum (VI) oxide (MoO3) anode is investigated as a possible energy storage device. Graphite cathode allows raising the voltage well above the cathode materials of LIBs without causing safety issues. The bottom potential of this anode is 2.0 V vs. Li/Li+, which is well above the lithium plating potential. Pulse polarization experiment reveals that no lithium deposition occurs, which further enhances the safety of the graphite/MoO3 full cell. Charge/discharge mechanism of this system results from intercalation and de-intercalation of the PF6- in the cathode (KS-6) and Li+ in the anode (MoO3). This mechanism is supported by in situ X-ray diffraction data of the graphite/MoO3 cell recorded at various states of charge. (C) 2011 Elsevier B.V. All rights reserved.