An approach to synthesis lithium iron orthosilicate with stable structure for high-performance lithium-ion battery cathodes

Due to the high theoretical capacity of ۳۳۲ mAhg−۱, lithium iron orthosilicate (Li۲FeSiO۴) was proposed as an alternative cathode material. Nevertheless, the electrochemical performance is compromised by the low electrical/ion conductivity and the stability of the crystal structure. In this study, high-purity Li۲FeSiO۴ particles (referred to as LFS) with a purity of more than ۹۸% were synthesized via a solid-state method, specifically to synthesize a stable crystal structure of orthorhombic Pmn۲۱. Physical properties and electrochemical performances of LFS were investigated. The materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive spectrometer (EDS). The electrochemical performances of the LFS cathode material were evaluated by galvanostatic charge-discharge and electrochemical impedance spectra (EIS) measurements. The results show an initial charge and discharge capacity of ۱۸۷.۴ and ۱۴۳.۵ mAhg-۱ at ۰.۱C. AC impendence study shows that synthesized LFS has low electrode/electrolyte interface resistance and high lithium-ion diffusion coefficient. This suggests that the material has remarkable properties when used as a cathode agent and improves charging performance in lithium-ion batteries