Wenze Han

Highly ordered staging structural interface between LiFePO4 and FePO4

A highly ordered interface between LiFePO(4) phase and FePO(4) phase with staging structure along the a axis and perpendicular to the b axis direction has been observed for the first time, in a partially chemically delithiated Li(0.90)Nb(0.02)FePO(4) by advanced aberration-corrected annular-bright-field (ABF) scanning transmission electron microscopy (STEM).

Carbon-coated rhombohedral Li3V2(PO4)3 as both cathode and anode materials for lithium-ion batteries: electrochemical performance and lithium storage mechanism

We report the electrochemical performance and storage mechanism of a symmetrical lithium-ion battery made of carbon-coated rhombohedral Li3V2(PO4)3 (r-LVP/C) as both the cathode and anode materials. The electrochemical evaluation of r-LVP/C in lithium half-cells demonstrates reversible lithium extraction/insertion reactions at 3.75 V and average 1.75 V vs. Li+/Li. Different storage mechanisms for the two reactions have been identified through ex situ and in situ X-ray diffraction measurements. A two-phase reaction takes place when two Li are extracted from r-LVP/C, while a solid-solution reaction occurs when two Li are inserted into r-LVP/C. In comparison, only one Na ion can be inserted into its sodium counterpart, Na3V2(PO4)3. Symmetrical batteries presented a high capacity of 120 mA h g−1 with an operating voltage of ∼2.0 V.