Li_3-2xNb_xCr_2-x(PO₄)₃ Complex Phosphates with the Nasicon Structure: Synthesis and lon Conductivity

Abstract

One of the main trends in the development of metal-ion batteries is the transition to lithium anodes, the safe use of which is impossible without replacing liquid membranes with solid membranes, primarily inorganic ones. Lithium-niobium-chromium phosphates with calculated compositions Li3–2xNbxCr2–x(PO4)3 (x = 0.95, 1.00, 1.05) were obtained by solid-state synthesis and characterized by XRD analysis and impedance spectroscopy. The obtained complex lithium-niobium-chromium phosphates with the NASICON structure crystallize in hexagonal modification. The lattice parameters of the synthesized materials decrease with increasing chromium content. The material of composition Li1.1Nb0.95Cr1.05(PO4)3 (3.10–5 S/cm at 25 °C) possesses the highest ionic conductivity and the lowest activation energy, which indicates a greater mobility of lithium ions by the interstitial mechanism even in the region of its own disorderliness.