(NH4)(0.5)V2O5 nanobelt is synthesized by sodium dodecyl benzene sulfonate (SOBS) assisted hydrothermal reaction as a cathode material for Li-ion battery. The as-prepared (NH4)(0.5)V2O5 nanobelts are 50-200 nm in diameter and several micrometers in length. The reversible lithium intercalation behavior of the nanobelts has been evaluated by cyclic voltammetry, galvanostatic discharge-charge cycling, and electrochemical impedance spectroscopy. The (NH4)(0.5)V2O5 delivers an initial specific discharge capacity of 225.2 mAh g(-1) between 1.8 and 4.0 V at 15 mA g(-1), and still maintains a high discharge capacity of 197.5 mAh g(-1) after 11 cycles. It shows good rate capability with a discharge capacity of about 180 mAh g(-1) remaining after 40 cycles at various rates and excellent cycling stability with the capacity retention of 81.9% after 100 cycles at 150 mA g(-1). Interestingly, the excess 120 mAh g(-1) capacity in the first charge process is observed, most of which could be attributed to the extraction of NH4+ group, verified by Fourier transform Infrared (FT-IR) and X-ray diffraction (XRD) results. (C) 2011 Published by Elsevier B.V.