Room temperature manufacture of dense NaSICON solid electrolyte films for all-solid-state-sodium batteries

Sodium (Na) Super-Ionic CONductor (NaSICON) solid electrolyte (SE) powders (Na3Zr2Si2PO4) were prepared by the mixed oxide technique using a planetary ball mill and synthesized via solid-state method at temperatures ranging from 950 to 1200 °C. The powders with 95% pure NaSICON phase were deposited on different substrates via Powder Aerosol Deposition (PAD) at room temperature directly from the powders and fully dense ceramic films were obtained. X-ray diffractometry including Rietveld refinement were carried out on both the calcined powders and the resulting films to determine the crystallographic properties. Subsequently, the electrical properties of the resulting films were characterized and the effect of annealing at temperatures between 100 and 600 °C on the ionic conductivity of NaSICON PAD films was evaluated. Annealed films were measured in the temperature range 50 and 250 °C to calculate the activation energy Ea of the PAD films. Our work demonstrates a successful room temperature deposition of dense NaSICON electrolyte films on different substrates, which is promising for stationary energy storage applications of solid-state-sodium batteries.