Toward understanding the lithiation/delithiation process in Fe0.5TiOPO4/C electrode material for lithium-ion batteries

We used Fe0.5TiOPO4/C composite as anode material for LIB and exhibits excellent cycling performance when the electrode is cycled in two different voltage ranges [3.0-1.3V] and [3.0- 0.02V] where different insertion mechanisms were involved. Based on in situ X-ray diffraction, in situ XANES spectroscopy results, and various electrochemical analyses at high and low voltage cut-off, we found that Fe0.5TiOPO4/C electrode materials still maintains its structure crystallinity after cycling between [3.0-1.3V] showing formation of new phase at the end of first discharge, with a reversible capacity of 100 mAhg-1 after 50 cycles at C/5 rate. Moreover, at highly lithiated states, [3.0-0.02V] voltage range, a reduction decomposition reaction highlights the Li-insertion/extraction behaviors, and low phase crystallinity is observed during cycling, in addition an excellent rate behavior and a reversible capacity of 250 mAhg- 1 can still be maintained after 50 cycles at high cycling rate 5C.