Powering Electric Vehicles with Ultrafast Dischargeable Vanadium Doped Lifepo4/C Cathode: The Experimental and Theoretical Investigations

Abstract

The electrochemical performance of vanadium doped LiFePO 4 is significantly enhanced as the electron conductivity and lithium ion diffusion capability are improved. These findings can promote the utilization of LiFePO 4 to power electric vehicles with faster acceleration and reliable long-term cycling stability. Herein, the theoretical calculation demonstrates the band structure of LiFePO 4 is optimized with effective reduction of the forbidden bandwidth after vanadium doping. Meanwhile, the energy barrier of lithium ion diffusion is decreased to achieve better high rate performance. The vanadium doped LiFePO 4 /C composites are synthesized via solid state method with iron powder as direct precursor and realize 100% atom efficiency as well as high tap density. The specific capacity and high rate performance are apparently ameliorated, 2% V-doped LiFe 0.98 V 0.02 PO 4 /C exhibits 141.4 mAh g -1 at 1 C and 93.9 mAh g -1 at 20 C, while the pristine counterpart only performs 130.1 mAh g -1 and 80.5 mAh g -1 , respectively. Furthermore, the capacity retention rate after 100 cycles at 1 C is 98.8% for LiFe 0.98 V 0.02 PO 4 /C. Based on these DFT calculation and experimental results, the dramatic improvement of vanadium doped LiFePO 4 /C materials may provide novel opportunities for the evolution of olivine cathode materials and stratify the application in electric vehicles.

Keywords: LiFePO4, vanadium doping, cathode material, DFT calculation