NASICON As-doped and glass additive dual strategy for novel NASICON-glass composite with superior ionic conductivity

Due to their desirable properties, NASICON-type LATP materials are considered strong candidates for use as solid-state electrolytes in lithium batteries. However, their ionic conductivity, essential for optimal battery performance, remains lower than liquid electrolytes. This study highlights the effectiveness of a dual-strategy approach to improve LATP NASICON materials' ionic conductivity. By substituting titanium with arsenic, we developed a high-ion-conducting phase, Li1.5Al0.3As0.2Ti1.5(PO4)3, which showed significant advancements, achieving a high relative density of 89% and an average grain size of 51 nm, which contributes to its improved performance. These modifications led to a significant boost in the ionic conductivity of the arsenic-doped LATP phase, which rose from 5.34 × 10-5 S.cm-1 for LATP to 8.57 × 10-4 S.cm-1 for the Li1.5Al0.3As0.2Ti1.5(PO4)3 phase at room temperature with an activation energy of 0.30 eV and a transference number close to 1. To address remaining porosity and grain boundary resistance, we developed a novel glass-ceramic composition by incorporating a high-ion-conducting glass additive (45Li2O-10Li2WO4-45P2O5) into the new elaborated Li1.5Al0.3As0.2Ti1.5(PO4)3 matrix. The addition of 3 wt.% glass content notably enhanced the density and compactness of the material, increasing its ionic conductivity to 4.6 × 10-3 S. cm-1 at 25 °C with an activation energy of 0.25 eV, representing the highest ionic conductivity reported for NASICON and NASICON-composite materials. This work provides a cost-effective and efficient method for producing novel NASICON ceramics and glass-ceramic composites with superior ionic conductivity, setting a new benchmark for NASICON-composite materials and advancing the development of high-performance solid-state electrolytes for lithium batteries.