Exceptional effect of glassy lithium fluorophosphate on Mn-rich olivine cathode material for high-performance Li ion batteries

摘要

Mn-rich olivine LiFe0.3Mn0.7PO4 is homogenously encapsulated by an similar to 3-nm-thick conductive nanolayer composed of the glassy lithium fluorophosphate through simple non-stoichiometric synthesis using additives of small amounts of LiF and a phosphorus source. The coating of the glassy lithium fluorophosphate nanolayer is clearly verified using transmission electron microscopy and X-ray photoelectron spectroscopy. It enables significant decrease in charge transfer resistance of LiFe0.3Mn0.7PO4 and improvement of its sluggish Li diffusion. At a rate of 10C, the LiFe0.3Mn0.7PO4 encapsulated by conductive glassy lithium fluorophosphate (LiFe0.3Mn0.7PO4-GLFP) electrode delivers a capacity of similar to 130 mAh g(-1), which is similar to 77% of its theoretical capacity (similar to 170 mAh g-1) and similar to 1.5 times higher than that of the pristine counterpart at 10C. Furthermore, LiFe0.3Mn0.7O4-GLFP achieves outstanding cycle stability (similar to 75% retention of its initial capacity over 500 cycles at 1C). The proposed olivine LiFe0.3Mn0.7PO4-GLFP battery is thus expected to be a promising candidate for large-scale energy storage applications.