Ionic Conductivity of Na3V2P3O12 as a Function of Electrochemical Potential and its Impact on Battery Performance

Abstract

Na3V2(PO4)3 (NVP) is a promising electrode material for sodium-ion batteries. However, many of its electrochemical properties like ionic conductivities have never been systematically studied. In the present paper, a battery cell with controlled morphology of NVP was prepared and the electrochemical impedance spectra were measured at various voltages. The ionic conductivity of NVP was calculated in dependence on applied potentials. NVP has a total conductivity of 1×10−6 S cm−1 at 2.9 V, which decreases to 8×10−8 S cm−1 at 3.5 V. This low conductivity, especially at higher voltages, influences the performance of batteries with an NVP electrode, especially by limiting the high-rate cycling of solid-state batteries.