A nanocomposite of molybdenum trioxide (MoO3) nanobelts coated with polypyrrole was prepared as an anode material for aqueous rechargeable sodium batteries (ARSBs). When nanowire Na0.35MnO2 is used as the cathode, the ARSB can deliver an energy density of 20 Wh kg−1 at 80Wkg−1 and even maintain 18 Wh kg−1 at 2.6kWkg−1 in 0.5molL−1 Na2SO4 aqueous electrolyte, suggesting a good rate capability that can be comparable with supercapacitors. In addition, its cycling behavior is greatly improved compared with the virginal MoO3. This will provide a new direction to explore non-carbon anode materials for ARSBs with excellent electrochemical performance. This good performance exhibits that this battery will be a promising candidate for the storage of solar and wind energies.