Gallium-substituted Nasicon Na3Zr2Si2PO12 solid electrolytes.

As a possible solid electrolyte material for solid-state sodium-based batteries, gallium-substituted Na 3 Zr 2 Si 2 PO 12 in the structure of Nasicon (sodium super ion conductor) has received hardly any attention so far, though Ga3+ has similar ionic radius close to that of Zr4+. Herein, a series of gallium-substituted Na 3 Zr 2 Si 2 PO 12 with formula of Na 3+x Zr 2-x Ga x Si 2 PO 12 (0 ≤ x ≤ 0.4) have been prepared through solid-state synthesis. The electrical, microstructural, and crystallographic performances of the developed solid electrolytes are systematically studied. In particular, the gallium-substituted Na 3.1 Zr 1.9 Ga 0.1 Si 2 PO 12 shows superior ionic conductivity of 1.06 × 10−3 S cm−1 at 25 °C, which is almost one order of magnitude higher than that of the pristine Na 3 Zr 2 Si 2 PO 12 , as well as low electronic conductivity of 6.17 × 10−8 S cm−1 and wide electrochemical stability window of 5 V vs. Na/Na+. This work demonstrates a new substituted strategy for exploring Na+-ion solid electrolytes. Image 1 • Substitution of Ga3+ for octahedral Zr4+ in Na 3 Zr 2 Si 2 PO 12 is proposed. • Tenfold increase in conductivity for Na 3.1 Zr 1.9 Ga 0.1 Si 2 PO 12 is achieved. • Conductivity dependence of bottleneck is demonstrated. [ABSTRACT FROM AUTHOR]