Comparative investigations of LiVPOF/C and LiV(PO)/C synthesized in similar soft chemical route.

Triclinic LiVPOF and monoclinic LiV(PO) are synthesized through a soft chemical process with mechanical activation assist, followed by annealing. In this process, ascorbic acid is used as reducing agent as well as carbon source. The as-prepared samples are coated with amorphous carbon. XPS analysis results show the expected valency states of ions in LiVPOF and LiV(PO). The electrochemical properties of the prepared LiVPOF/C and LiV(PO)/C cathodes are evaluated. The as-prepared LiVPOF/C cathode shows an initial discharge specific capacity of 140 ± 3 mAh g at 30 mA g in the voltage range of 3.0~4.4 V, compared with that of 138 ± 3 mAh g possessed by LiV(PO)/C. Both samples exhibit good cycle performance at different current densities. The capacity delivered by LiVPOF remains 95.5 and 91.7 % of its initial discharge capacity after 50 cycles at 150 and 750 mA g, respectively, while 97.4 and 90.6 % for LiV(PO)/C. But the rate capability of LiVPOF/C is not so good compared with as-prepared LiV(PO)/C. [ABSTRACT FROM AUTHOR]