NASICON-type Li1+2xZr2−xCax(PO4)3 with high ionic conductivity at room temperature

Abstract

Compounds with nominal formula Li_1+2xZr_2−xCa_x(PO₄)₃ (x = 0.1–0.4) were synthesized and the substitution effects on surface morphology, density and ionic conductivity were investigated. With the introduction of Ca²⁺, the rhombohedral NASICON structure is retained at room temperature. The maximum Li⁺-ion conductivity at room temperature is 0.49 × 10⁻⁴ S cm⁻¹ with an activation energy of 0.48 eV with x = 0.1. A Ca²⁺-rich grain boundary is formed with x > 0.1, which results in a significant decrease in density and ionic conductivity.