Synthesis of Na ion-electron mixed conductor Na3Zr2Si2PO12 by doping with transition metal elements (Co,Fe, Ni)

NASICON solid electrolyte Na₃Zr₂Si₂PO₁₂ (NZSP) exhibits high chemical stability and can be utilized as cladding materials of cathodes to improve battery cycle stability. However, the electronic conductivity of NZSP is extremely low (∼10⁻⁹ S cm⁻¹), which will hinder the electron conduction of cathode materials. To address this issue, the electronic conductivity of NZSP is improved by doping with transition metal elements (Co, Fe, Ni). Co-doped NZSP has an electronic conductivity of 5.03 × 10⁻⁶ S cm⁻¹. On the other hand, the ionic conductivity of doped samples remains stable, even slightly increased. The mechanical properties of pristine and doped samples are characterized with a micro indenter, which is also a key parameter for coating materials.