Electrical Property of Nasicon (Na3Zr2Si2PO12) as Solid-Electrolyte for Na/S Battery

Na/S battery attracts a lot of attention due to low cost and high energy density for burgeoning large-scale energy storage system. The battery operates at elevated temperature (~300^oC), so solid electrolyte which separates molten electrodes is used.¹ Beta alumina is widely used as solid electrolyte but it has anisotropic electrical properties and complicated synthesis. In this point of view, Nasicon (Na super ionic Conductor) can be a promising alternative because it has 3-dimensional Na conducting channels and can be obtained by a facile synthesis.

Nasicon (Na_1+xZr₂Si_xP_3-xO₁₂) has wide composition range (0<x<3) and ionic conductivity of the materials is highest when x equals to 2. However, Nasicon structure goes through transformation from monoclinic phase (Low T) to rhombohedral phase (high T). This phase transformation really affects durability of the solid electrolyte because volumetric change during thermal cycles happens. Thus, the depression of phase transformation is important for high durability.

In this presentation, we will discuss about experimental parameters that influence on the phase transformation and will discuss electrical properties of Nasicon phase using EIS (Electrochemical impedance spectroscopy) measurement

Reference

1. V. Palomares et al., Energy & Environmetal Science, 5, 5884-5901, 2012