New Phosphate-based Electrode Material for High Performance Sodium-Ion Batteries

A new Nasicon-type phosphate Na 3 ZrCo(PO 4 ) 3 is successfully synthesized using a sol-gel method. In this study, we investigate the synthesis, structural and electrochemical properties of this 3D phosphate. The Rietveld refinement of the XRD pattern showed that at room temperature, the material exhibits a hexagonal symmetry with the space group (R-3) and the cell parameters a = 8.931(3) A; c = 22.310(1) A. The structure of Na 3 ZrCo(PO 4 ) 3 consists of edge sharing [MO6] octahedra (M = Zr, Co) resulting in chains parallel to [-101]. These chains are linked together via the [PO4] tetrahedra to form two distinct tunnels in which sodium cations are located. The synthesized Na 3 ZrCo(PO 4 ) 3 were tested in sodium half-cell. An initial discharge capacity of 120 mAhg−1at C/20 for the first cycle and good capacity retention at high rates were obtained.