Triclinic Na2-xFe1+x/2P2O7/C composite was prepared by glass-ceramics method. We found that Na2-xFe1+x/2P2O7/C composite can be used as cathode active materials for Sodium ion battery with high current density rate performance over 10C (2 mA cm(-2)) condition and stable electrochemical cycle performance. A 2 mu m glass precursor powder in composition of Na2-xFe1+x/2P2O7 (x = 0-0.44) was crystallized in tubular furnace around 600 degrees C with carbon source to reduce iron valence state and to coat grain surface with carbon. By means of charge discharge testing Na2FeP2O7/C composite exhibits 86 mAh g(-1) (253 Wh kg(-1)) as reversible discharge energy density that is half amount of that for LiFePO4, however in 10C condition they kept 45 mAh g(-1) (110 Wh kg(-1)) even in 2 mu m grain size. (C) 2012 Elsevier B.V. All rights reserved.