Synthesis and electrochemical performance of Li2FeSiO4/C cathode material using ascorbic acid as an additive

Carbon-coated Li2FeSiO4 composite (LFS/C-AA) was synthesized via a refluxing-assisted solid-state reaction by using ascorbic acid as additive and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, galvanostatic charge/discharge measurements, and electrochemical impedance spectra (EIS) tests. The results show that ascorbic acid can to some extent prohibit the oxidation of Fe2+ during the synthesis process, and the pyrolytic carbon from ascorbic acid shows higher electronic conductivity and improves the degree of graphitization of residual carbon in the LFS/C-AA composite. Compared with LFS/C prepared without ascorbic acid, LFS/C-AA displays better electrochemical performance. The desirable property is attributed to the reduced particle size, the enhanced electronic conductivity, and the improved diffusion coefficient of lithium ions.