(NH4)0.5V2O5 nanobelt is synthesized by sodium dodecyl benzene sulfonate (SDBS) assisted hydrothermal reaction as a cathode material for Li-ion battery. The as-prepared (NH4)0.5V2O5 nanobelts are 50–200nm 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)0.5V2O5 delivers an initial specific discharge capacity of 225.2mAhg−1 between 1.8 and 4.0V at 15mAg−1, and still maintains a high discharge capacity of 197.5mAhg−1 after 11 cycles. It shows good rate capability with a discharge capacity of about 180mAhg−1 remaining after 40 cycles at various rates and excellent cycling stability with the capacity retention of 81.9% after 100 cycles at 150mAg−1. Interestingly, the excess 120mAhg−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.