Enhanced lithium storage in Fe-doped Li3V2(PO4)3-Li3PO4/C composite cathodes

초록

A carbon-coated Li3V2(PO4)(3)-Li3PO4 (LVP/LP/C) composite lithium-ion battery (LIB) cathode material with low Fe doping (LVFP/LP/C) is prepared using a facile hydrothermally assisted sol-gel method at a relatively lower annealing temperature (750 degrees C). Characterization techniques, including Fourier transform infrared (FTIR), Raman, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA), confirm its structural and morphological properties. Electrochemical evaluation shows superior performance as an LIB cathode in a half-cell, exhibiting a high initial discharge capacity of 124.3 mAh g(-1) and excellent capacity retention of 97.3 % after 200 cycles at 100 mA g(-1) in the 3.0-4.3 V (vs. Li/Li+) voltage window. The full-cell (LVFP/LP/C||graphite) also demonstrates excellent performance, achieving a reversible capacity of 73.5 mAh g(-1) and similar to 81.9 % retention after 85 cycles at 0.5C, with outstanding rate capability. Carbon coating enhances conductivity, while Li3PO4 protects active materials by mitigating electrolyte decomposition and facilitating Li-ion diffusion. Fe doping introduces lattice defects, further improving conductivity and performance. These findings highlight the potential of surface modification and metal doping for advanced high-energy-density LIB cathode materials.

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