Synthesis, crystal structure and magnetic properties of a new lithium cobalt metaphosphate, LiCo(PO3)3

A new lithium cobalt metaphosphate, LiCo(PO3)3, is reported for the first time, which was discovered during the exploratory synthesis in Li–Co–P–O system by solid state reaction. The structure has been refined by powder X-ray Rietveld refinement method (P212121, a = 8.5398(2) Å, b = 8.6326(2) Å and c = 8.3520(2) Å, Z = 4, Rp = 13.6%, Rwp = 19.4%, Rexp = 17.7%, S = 1.11, χ2 = 1.23). It is isostructural with LiM(PO3)3 (M = Fe, Cu). It contains (PO3)1− chains with the Co atoms localized in the octahedral sites, bridging four neighboring chains. The magnetic susceptibility measurement showed a typical paramagnetic behavior of high spin of Co2+, following the Curie–Weiss law in the temperature range of 5–300 K. Unlike the olivine type lithium cobalt phosphate, LiCoPO4, cyclic voltammetry of LiCo(PO3)3 assembled in the coin-type cell showed no electrochemical activity in the voltage region of 1–5 V versus Li/Li+.