Preparation of lithium ferromanganese phosphate by non-stoichiometric strategy

Abstract

LixFexMn1-xPO4 exhibits low production costs, environmental friendliness, high energy density, thermal stability, and cycling stability in lithium-ion batteries (LIBs), presenting broad application prospects. Furthermore, studies have shown that adopting a non-stoichiometric ratio strategy can reduce particle size, decrease anti-site defects, and generate a conductive impurity phase on the material surface. This leads to an enhancement in the electrochemical performance of the material, making it an effective approach to achieving high-performance olivine-type cathode materials. In this study, three materials were successfully prepared using the solid-phase method: Li1.05Fe0.5Mn0.475PO4/C, Li1.05Fe0.5Mn0.5PO4/C, and Li1.05Fe0.475Mn0.5PO4/C. The physical properties of the materials were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The electrochemical performance including specific capacity, rate performance, and cycling performance were studied through charge-discharge tests, with Li1.05Fe0.5Mn0.475PO4/C exhibiting the best specific capacity at all rates. At rates of 0.1 C, 0.5 C, 1 C, 2 C, and 5 C, its average reversible specific capacities were 143.5, 129.5, 122.1, 112.8, and 97.3 mAh·g−1, respectively. Furthermore, differences in electrochemical performance of three materials were discussed in detail through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).