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 (similar to 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 x 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.