Optimization of synthesis conditions of high-tap density FeVO4 hollow microspheres via spray pyrolysis for lithium-ion batteries

Iron orthovanadate (FeVO4) hollow microspheres were synthesized by a continuous, one-step, scalable process without the addition of a template material using the ultrasonic spray pyrolysis method. The synthesis conditions were optimized by changing the synthesis temperature in order to synthesize hollow microspheres of FeVO4 under the constant N-2 gas atmosphere by means of a tubular furnace. The pure crystalline phase of hollow microspheres was achieved at 800 degrees C, and investigated using XRD, RAMAN, SEM, TEM. The electrochemical performance of hollow microspheres was considered with initial specific discharge/charge capacities of 1373.82 mA h g(-1), 1107.28 mA h g(-1), and an initial columbic efficiency of 80.59% at 0.1 C up to 100 cycles. Superior rate capability and cycle retention performance were due to the FeVO4 hollow microsphere morphology and high tap density, which improved the electrical contact between the electrolyte, active material, and current collector and shortened the diffusion length of Li+ ions during the intercalation/de-intercalation process. Moreover, electrical impedance spectroscopic measurements explained that the enhanced ionic conductivity was due to the morphology and porosity which improved the electrochemical performance of FeVO4 hollow microspheres and proved it as an auspicious anode material for LIBs.