Electrochemical characterization of micro-rod β-Na_0.33V₂O₅ for high performance lithium ion batteries

High-purity micro-rod β-Na_0.33V₂O₅ particles 2-5 μm in width and 3-10 μm in length are prepared by the chemical switch method. Electrochemical characterization demonstrates that micro-rod β-Na_0.33V₂O₅ as a cathode material for lithium ion batteries provides high discharge capacity, good rate-capability, and cyclic stability. It delivers high discharge capacities of 297, 245, 220, and 178 mAh g^-1 at current densities of 0.1, 0.2, 0.5, and 1 C-rate, respectively. The capacity fading rate is less than 1% per cycle, with high volumetric discharge capacities (504 mAh cm^-3 at 0.1C and 301 mAh cm^-3 at 1 C). Scanning electron microscopy images of the micro-rods during cycling indicate that they have excellent crystal structural reversibility in the voltage range of 1.5-4.0 V. These superior electrochemical properties are attributed to the tunneled crystal structure and internal pores formed by crystal defects in the micro-rods.