Carbon coated Na3V2(PO4)(3) as novel electrode material for sodium ion batteries

A Na3V2(PO4)(3) sample coated uniformly with a layer of 6 nm carbon has been successfully synthesized by a one-step solid state reaction. This material shows two flat voltage plateaus at 3.4 V vs. Na+/Na and 1.63 V vs. Na+/Na in a nonaqueous sodium cell. When the Na3V2(PO4)(3)/C sample is tested as a cathode in a voltage range of 2.7-3.8 V vs. Na+/Na, its initial charge and discharge capacities are 98.6 and 93 inAh/g. The capacity retention of 99% can be achieved after 10 cycles. The electrode shows good cycle performance and moderate rate performance. When it is tested as an anode in a voltage range of 1.0-3.0 V vs. Na+/Na, the initial reversible capacity is 66.3 mAh/g and the capacity of 59 mAh/g can be maintained after 50 cycles. These preliminary results indicate that Na3V2(PO4)(3)/C is a new promising material for sodium ion batteries. (C) 2011 Elsevier B.V. All rights reserved.