Synthesis of LiFePO4 cathode materials from amorphous FePO4 precursor: Effects of Li/P molar ratio on crystal defect formation and electrochemical performance

As an excellent cathode material, lithium iron phosphate (LiFePO 4 ) has been widely used in commercial lithium-ion batteries (LIBs). However, the impact of synthetic conditions on LiFePO 4 cathode derived from amorphous iron phosphate (FePO 4 ) remains underexplored. In the present study, the effects of Li/P molar ratio on the crystallinity and electrochemical properties of LiFePO 4 were investigated in detail using FePO 4 as a precursor. When the Li/P molar ratio in LiFePO 4 was approximately 1, the material exhibited an excellent long-term cycling stability with a high capacity retention of 97 % after 500 cycles. In addition, multiple characterizations demonstrate that the higher molar ratio of the Li/P resulted in the higher concentration of defects in LiFePO 4 crystals, which not only reduced the reversible capacity but also compromised the structural stability, leading to a poor cyclic stability and quick capacity degradation. Therefore, such a work could provide a scientific insight for rational design and synthesis of high-performance LiFePO 4 cathodes from amorphous FePO 4 precursor.