Fabrication of Y-Doped and Ce-Doped NaSICON through Integrated Mechanical and Thermal Activation Method

NaSICON (Na Super Ionic CONductor) materials have emerged as promising candidates for a wide range of applications such as all-solid-state Na-ion batteries, sodium-air batteries, electrochemical sensors, as electrolytes for thermoelectric generators, and membranes due to their high availability, profound ionic conductivity, high thermal and chemical stability, and good electrochemical compatibility. To be used in energy storage devices, the high ionic conductivity with relatively low interfacial resistance has to be possessed. However, the Na-ion conductance at room temperature remains several orders of magnitude lower than organic electrolytes even NaSICONs have relatively high ionic conductivity at elevated temperature. Therefore, there is still a need in developing a consistent manufacturing process to further increase the ionic conductivity of NaSICON and reducing the production cost for synthesizing NaSICON membranes.<br/><br/>This study aims to improve the density and ionic conductivity of yttrium and cerium-doped NASICON materials through mechanical activation and one-step sintering process while suppressing the manufacturing cost of NaSICONs. Here, we report the feasibility of integrated mechanical and thermal activation method in doping the zirconium site in NaSICON. Fully densified Y-doped NaSICON has 100% higher total conductivity at the room temperature then the same material prepared from general solid-state sintering method, while Ce-doped NaSICON demonstrates the good bulk conductivity of 4.7 x 10^-4 S/cm. This study will provide an alternate solution for synthesizing high ionic conductivity NaSICON at low cost for many energy storage systems.