For the first time, belt-like V6O13 precursor was synthesized via a simple solvothermal method. Rod-like Ag-doped V6O13 was successfully synthesized by this method followed by heating at 350 °C. Both crystal domain size, electronic conductivity, and the lithium diffusion coefficient of the Ag-doped V6O13 samples are influenced by the added amount of AgNO3. When the amount of AgNO3 is 0.008 g, the product is rod-like particles, which are 0.1–0.3 μm wide and 1–2 μm long, and exhibits the best electrochemical performance. The enhanced electrochemical performance originates from its higher total conductivity, higher lithium diffusion coefficient, and better structural reversibility.