Improved Cycle Performance of Sulfur-Doped LiFePO4 Material at High Temperatures

摘要

Pristine and sulfur-doped (LiFePO3.98S0.03) lithium iron phosphates were synthesized by a sol-gel method. The XRD pattern of the prepared materials suggested an orthorhombic structure with a Pnma space group and an absence of impurities. The Li/LiFePO4 or LiFePO3.98S0.03 cells were employed for cycling studies at various temperatures (25, 50 and 60 oC). In all cases, the Li/LiFePO3.98S0.03 cell showed an improved performance with a stable discharge behavior of ~155 mAhg-1. Nevertheless, pristine LiFePO4 cells presented poor discharge behavior at elevated temperatures, especially 60 oC.