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Synthesis and enhanced electrochemical performance of Li2CoPO4F cathodes under high current cycling

2012; Royal Society of Chemistry; Volume: 14; Issue: 34 Linguagem: Inglês

10.1039/c2cp41624g

1463-9084

Amaresh Samuthira Pandian, G. J. Kim, K. Karthikeyan, Vanchiappan Aravindan, Kyung Yoon Chung, Byung Won Cho, Y. S. Lee,

Supercapacitor Materials and Fabrication

Lithium cobalt fluorophosphate, Li(2)CoPO(4)F, is successfully synthesized by a solid state reaction under Ar flow at 700 °C. X-ray diffraction and scanning electron microscopic studies are utilized to analyze the structural and morphological features of the synthesized materials, respectively. The presence of fluorine is also supported by energy-dispersive X-ray spectroscopy. The electrochemical properties are evaluated by means of Li/Li(2)CoPO(4)F half-cell configurations in both potentiostatic and galvanostatic modes. The Li/Li(2)CoPO(4)F cell delivers an initial discharge capacity of 132 mA h g(-1) at a current density of 0.1 mA cm(-2) between 2.0 and 5.1 V at room temperature. Due to the higher operating potential of the Co(2+/3+) couple in the fluorophosphate matrix, this cell shows a capacity retention of only 53% after 20 cycles, still the material delivered 108 mA h g(-1) at a high current rate of 1 C. Cyclic voltammetric studies corroborate the insertion and extraction of Li(+) ions by a single phase reaction mechanism during cycling.