Impact of adding Fe ions on the local structure and electrochemical performance of P2O5–V2O5 glass and glass ceramics used as a cathode in LIBs

Abstract

Due to their low cost and non-toxic characteristics, iron-vanadium-phosphate glass and glass ceramics as a cathode in lithium-ion batteries (LIBs) promise an excellent storage system. The impact of adding Fe2O3 has been studied on the local structure, electric conductivity, and battery performance of xFe2O3.(60-x)V2O5.40P2O5(10≤x ≤ 50mol%) glass and glass ceramics, abbreviated as xFVP, were prepared by the melt quenching method. The xFVP glass and glass-ceramics series were scientifically studied before (BHT) and after heat treatment (HT) at 500 °C for 100 min. The X-ray diffraction patterns (XRD), 57Fe-Mössbauer spectra (FeMS), X-ray absorption fine structure (XAFS), Fourier transform infrared spectroscopy (FTIR), DC conductivity, and charge-discharge capacity were achieved in this study. The XRD data of xFVP-BHT glasses confirmed the amorphous nature as 'x' increased from 10 to 30 mol%. Also, we found several sharp diffraction lines in the XRD patterns of xFVP-BHT and xFVP-HT, which are attributed to the FePO4, Fe3.5(PO4)3, (VO)(PO4), FePVO6, and V2O5 crystalline phases. Furthermore, with Fe2O3 increasing from 10 to 50 mol%, the DC conductivity of xFVP glass ceramics at room temperature decreased from 1.14 × 10−6 (Ω cm)−1 to 5.99 × 10−8 (Ω cm)−1. The highest initial capacity is 342 mAh g−1 recorded in 10FVP-BHT, measured at a current density of 50 mA g−1. In conclusion, Fe ions were added to the phosphate-vanadate glass to enhance the local structure and improve the cyclability of xFVP glasses as a cathode, making these glasses a promising active material for high-performance cathode LIBs.