Thermally Controlled V2O5 Nanoparticles as Cathode Materials for Lithium-Ion Batteries with Enhanced Rate Capability

Abstract Vanadium pentoxide (V 2 O 5 ) is an attractive cathode material for lithium-ion batteries (LIBs) because of its low cost, high abundance, and relatively high theoretical capacity (294 mA h g −1 with two lithium insertions/extractions per unit formula at 2.0–4.0 V). However, practical applications of V 2 O 5 are hampered by its poor structural stability, low electrical conductivity, and slow ion diffusion kinetics, resulting in poor long-term cycling stability and rate performance. In this study, V 2 O 5 nanoparticles are synthesized by a fast sol-gel method with citric acid (C 6 H 8 O 7 ) at 400, 500, 600, and 700 °C. The thickness of the amorphous layers on the surface of the V 2 O 5 nanoparticles is controlled from approximately 4–5 to 1–2 nm by adjusting the calcination temperature. The V 2 O 5 nanoparticles synthesized at 600 °C show better electrochemical performances than the other samples. They exhibit a high initial discharge capacity of 276 mA h g −1 between 2.1 and 4.0 V at a rate of 1 C, and good capacity retention of 83% after 50 cycles. Even at 10 C rate, a discharge capacity of about 168 mA h g −1 is obtained after 100 cycles. The excellent rate capability and cycling stability are also achieved at current densities of 0.5–20 C.