Ionic and Thermal Transport in Na-Ion-Conducting Ceramic Electrolytes

Abstract

We have studied the ionic and thermal transport properties along with the thermodynamic key properties of a Na-ion-conducting phosphate ceramic. The system Na1+xAlxTi2−x(PO4)3 (NATP) with x = 0.3 was taken as a NASICON-structured model system which is a candidate material for solid electrolytes in post-Li energy storage. The commercially available powder (NEI Coorp., USA) was consolidated using cold isostatic pressing before sintering. In order to compare NATP with the “classical” NASICON system, Na1+xZr2(SiO4)x(PO4)3−x (NaZSiP) was synthesized with compositions of x = 1.7 and x = 2, respectively, and characterized with regard to their ionic and thermal transport behavior. While ionic conductivity of the NaZSiP compositions was about more than two orders of magnitude higher than in NATP, the thermal conductivity of the NASICON compound showed an opposite behavior. The room temperature value was about a factor two higher in NATP compared to NaZSiP. While the thermal conductivity decreases with increasing temperature in NATP, it increases with increasing temperature in NaZSiP. However, the overall change of this thermal transport parameter over the measured temperature range from room temperature up to 800 °C appeared to be relatively small.

Thermal Conductivities of Lithium-Ion-Conducting Solid Electrolytes

“…In agreement with the thermal diffusivities, all investigated electrolytes show astonishingly low thermal conductivities, consistently below 1 W m -1 K -1 with almost no temperature dependence. This result corroborates other reports on sodium , and lithium , ionic conductors and strengthens the hypothesis of glass-, respectively, diffuson-like thermal transport in solid electrolytes. With that, the magnitudes of thermal conduction are not only comparable to but even below those of thermoelectric materials and thermal barrier coating specifically engineered for low thermal conductivity.…”

“…Recent studies suggest that thermal conductivities of most solid electrolytes, both sulfide , and oxide-based , , have low thermal conductivities (0.5 to 1.5 W m –1 K –1 ) comparable to liquid carbonate-based electrolytes − (0.6 W m –1 K –1 ) used in conventional systems. Consequently, thermal management challenges in Li-ion batteries that originate from poor heat dissipation (depending on the thermal conductivity) can be expected in solid-state systems as well .…”

3D Printing of Na1.3Al0.3Ti1.7(PO4)3 Solid Electrolyte via Fused Filament Fabrication for All‐Solid‐State Sodium‐Ion Batteries

“…The activation energies are 0.58 (45) eV and 0.57 (52) eV for the printed and pressed samples, respectively, and are within the range of reported literature values (0.54-0.61) eV. [46,47] The activation energies are accessible since the ionic conductivity follows the Arrhenius law, with equation ( 2).…”

Unconventional Behavior of Na2O in MgO-V2O5 Glasses in Comparison to Silicate Glasses

“…The conduction process can be determined through the activation energy. The activation energy lies in the 0.9–1.5 eV range for ionic conductivity. , Below this range, mixed conduction is observed, i.e., electronic + ionic conductivity followed by electronic conductivity at lower temperature regions. The calculated activation by the Arrhenius plot lies in the range of 0.30–0.55 eV.…”

“…The activation energy lies in the 0.9−1.5 eV range for ionic conductivity. 46,47 Below this range, mixed conduction is observed, i.e., electronic + ionic conductivity The highest conductivity is observed for the MVN-12 sample, i.e., 5.13 × 10 −2 S/cm at 250 °C, which is four orders higher than the room temperature conductivity of the MVN-0 sample.…”