Structural and Li-ion diffusion properties of lithium tantalum phosphate LiTa2PO8

We synthesized a polycrystalline LiTa2PO8 sample at 1323 K by a solid-state reaction. The crystal structure of LiTa2PO8 was examined by selected-area electron diffraction (SAED) and convergent-beam electron diffraction (CBED) techniques. Electrochemical impedance measurements showed that the total conductivity at room temperature was 4.85 x 10(-4) S cm(-1) and the activation energy was 0.52 eV. The high Li-ion conductive properties were confirmed by Li-7 pulse-field gradient (PFG) or pulse-gradient spin-echo (PGSE) NMR spectroscopy. The activation energy of the Li diffusion (0.51 eV) measured by PFG NMR was well consistent with the result of impedance measurement. We believe that the LiTa2PO8 would be as one of the important candidates for the solid electrolyte used in all solid-state lithium batteries.