High Ionic Conducting and Flexible Nasicon Membranes Enabled By Integrated Mechanical and Thermal Activation and Co-Sintering

NaSICON-type materials have been investigated since 70s and become an attractive candidate for energy storage and many other emerging applications due to their good ionic conductivity. However, further enhancement in ionic conductivity and mechanical flexibility at room temperature and facile processing methods to synthesize NaSICON in an energy efficient and low cost facet are required to enable various emerging applications. In this study, we report a novel processing method, termed integrated mechanical and thermal activation associated with co-sintering of stainless steel to address these challenges. It is found that Na 3 Zr 2 Si 2 PO 12 membranes with little or no impurity, and total ionic conductivity of 1.53 × 10 -3 S/cm at room temperature can be synthesized through one high-energy ball milling step followed by one high-temperature reaction, which significantly simplifies the synthesizing procedure for NaSICON membranes and achieves the high ionic conductivity. It is shown that further co-sintering of pure NaSICON and stainless steel has successfully increased the mechanical robustness of membrane while retaining good ionic conductivity reported in the literature. This study has provided a sturdy processing to synthesize high performance yet low cost NaSICON and NaSICON/stainless steel composite membranes that suitable for real world application.