Synthesis and electrochemical performance of Li₂Co_1−xM_xPO₄F (M = Fe, Mn) cathode materials

In the search for high-energy materials, novel 3D-fluorophosphates, Li₂Co_1−xFe_xPO₄F and Li₂Co_1−xMn_xPO₄F, have been synthesized. X-ray diffraction and scanning electron microscopy have been applied to analyze the structural and morphological features of the prepared materials. Both systems, Li₂Co_1−xFe_xPO₄F and Li₂Co_1−xMn_xPO₄F, exhibited narrow ranges of solid solutions: x ≤ 0.3 and x ≤ 0.1, respectively. The Li₂Co_0.9Mn_0.1PO₄F material demonstrated a reversible electrochemical performance with an initial discharge capacity of 75 mA·h·g⁻¹ (current rate of C/5) upon cycling between 2.5 and 5.5 V in 1 M LiBF₄/TMS electrolyte. Galvanostatic measurements along with cyclic voltammetry supported a single-phase de/intercalation mechanism in the Li₂Co_0.9Mn_0.1PO₄F material.