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

Abstract

Vanadium pentoxide (V2O5) is an attractive cathode material for lithium-ion batteries (LIBs) because of its low cost, high abundance, and relatively high theoretical capacity (294mAhg−1 with two lithium insertions/extractions per unit formula at 2.0–4.0V). However, practical applications of V2O5 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, V2O5 nanoparticles are synthesized by a fast sol-gel method with citric acid (C6H8O7) at 400, 500, 600, and 700°C. The thickness of the amorphous layers on the surface of the V2O5 nanoparticles is controlled from approximately 4–5 to 1–2nm by adjusting the calcination temperature. The V2O5 nanoparticles synthesized at 600°C show better electrochemical performances than the other samples. They exhibit a high initial discharge capacity of 276mAhg−1 between 2.1 and 4.0V at a rate of 1C, and good capacity retention of 83% after 50 cycles. Even at 10C rate, a discharge capacity of about 168mAhg−1 is obtained after 100 cycles. The excellent rate capability and cycling stability are also achieved at current densities of 0.5–20C.