“…The large fraction of vacant Na sites and the favourable connection of their polyhedra ensure rapid exchange of the Na + ions as discussed in literature 22,40 . The preparation and characterisation of the samples studied here (NZSP and Sc-NZSP) has already been described elsewhere 18,22 . The characterization also includes analyses by X-ray powder diffraction and differential scanning measurements.Figure 1Crystal structure and conductivity.…”
Section: Resultsmentioning
confidence: 99%
“…Although moderate to very fast ion conducting Na compounds have so far been frequently presented; 15,16,18–21 ; ion dynamics in non-sulfidic, i . e ., air-insensitive, Na + electrolytes with extremely high ion conductivities exceeding 1 mS/cm at room temperature have, apart from the well-known Na- β ′′-alumina 12 , only very rarely been characterized in detail 16,18,22 .…”
Section: Introductionmentioning
confidence: 99%
“…e ., air-insensitive, Na + electrolytes with extremely high ion conductivities exceeding 1 mS/cm at room temperature have, apart from the well-known Na- β ′′-alumina 12 , only very rarely been characterized in detail 16,18,22 . Here we present an in-depth study to explore the roots of extremely rapid 3D ion dynamics in Na 3.4 Sc 0.4 Zr 1.6 (SiO 4 ) 2 PO 4 (Sc-NZSP), which was prepared via a wet-chemical route 18 . The parent compound Na 3 Zr 2 (SiO 4 ) 2 PO 4 (NZSP), following the pioneering work of Hong and Goodenough 23,24 , served as benchmark.…”
The realization of green and economically friendly energy storage systems needs materials with outstanding properties. Future batteries based on Na as an abundant element take advantage of non-flammable ceramic electrolytes with very high conductivities. Na3Zr2(SiO4)2PO4-type superionic conductors are expected to pave the way for inherently safe and sustainable all-solid-state batteries. So far, only little information has been extracted from spectroscopic measurements to clarify the origins of fast ionic hopping on the atomic length scale. Here we combined broadband conductivity spectroscopy and nuclear magnetic resonance (NMR) relaxation to study Na ion dynamics from the µm to the angstrom length scale. Spin-lattice relaxation NMR revealed a very fast Na ion exchange process in Na3.4Sc0.4Zr1.6(SiO4)2PO4 that is characterized by an unprecedentedly high self-diffusion coefficient of 9 × 10−12 m2s−1 at −10 °C. Thus, well below ambient temperature the Na ions have access to elementary diffusion processes with a mean residence time τNMR of only 2 ns. The underlying asymmetric diffusion-induced NMR rate peak and the corresponding conductivity isotherms measured in the MHz range reveal correlated ionic motion. Obviously, local but extremely rapid Na+ jumps, involving especially the transition sites in Sc-NZSP, trigger long-range ion transport and push ionic conductivity up to 2 mS/cm at room temperature.
“…The large fraction of vacant Na sites and the favourable connection of their polyhedra ensure rapid exchange of the Na + ions as discussed in literature 22,40 . The preparation and characterisation of the samples studied here (NZSP and Sc-NZSP) has already been described elsewhere 18,22 . The characterization also includes analyses by X-ray powder diffraction and differential scanning measurements.Figure 1Crystal structure and conductivity.…”
Section: Resultsmentioning
confidence: 99%
“…Although moderate to very fast ion conducting Na compounds have so far been frequently presented; 15,16,18–21 ; ion dynamics in non-sulfidic, i . e ., air-insensitive, Na + electrolytes with extremely high ion conductivities exceeding 1 mS/cm at room temperature have, apart from the well-known Na- β ′′-alumina 12 , only very rarely been characterized in detail 16,18,22 .…”
Section: Introductionmentioning
confidence: 99%
“…e ., air-insensitive, Na + electrolytes with extremely high ion conductivities exceeding 1 mS/cm at room temperature have, apart from the well-known Na- β ′′-alumina 12 , only very rarely been characterized in detail 16,18,22 . Here we present an in-depth study to explore the roots of extremely rapid 3D ion dynamics in Na 3.4 Sc 0.4 Zr 1.6 (SiO 4 ) 2 PO 4 (Sc-NZSP), which was prepared via a wet-chemical route 18 . The parent compound Na 3 Zr 2 (SiO 4 ) 2 PO 4 (NZSP), following the pioneering work of Hong and Goodenough 23,24 , served as benchmark.…”
The realization of green and economically friendly energy storage systems needs materials with outstanding properties. Future batteries based on Na as an abundant element take advantage of non-flammable ceramic electrolytes with very high conductivities. Na3Zr2(SiO4)2PO4-type superionic conductors are expected to pave the way for inherently safe and sustainable all-solid-state batteries. So far, only little information has been extracted from spectroscopic measurements to clarify the origins of fast ionic hopping on the atomic length scale. Here we combined broadband conductivity spectroscopy and nuclear magnetic resonance (NMR) relaxation to study Na ion dynamics from the µm to the angstrom length scale. Spin-lattice relaxation NMR revealed a very fast Na ion exchange process in Na3.4Sc0.4Zr1.6(SiO4)2PO4 that is characterized by an unprecedentedly high self-diffusion coefficient of 9 × 10−12 m2s−1 at −10 °C. Thus, well below ambient temperature the Na ions have access to elementary diffusion processes with a mean residence time τNMR of only 2 ns. The underlying asymmetric diffusion-induced NMR rate peak and the corresponding conductivity isotherms measured in the MHz range reveal correlated ionic motion. Obviously, local but extremely rapid Na+ jumps, involving especially the transition sites in Sc-NZSP, trigger long-range ion transport and push ionic conductivity up to 2 mS/cm at room temperature.
“…As polycrystalline ceramics, some compositions demonstrate similar ionic conductivity to Na + ‐ß′′‐Al 2 O 3, reaching several mS/cm at room temperature, and are worth being reconsidered as electrolyte materials in sodium batteries . Na 3 Zr 2 (SiO 4 ) 2 (PO 4 ), hereafter abbreviated as NZSP, is the most commonly studied NASICON material that also has excellent electrical properties . The reported conductivity of NZSP varies from 9.2 × 10 −5 to 1.2 × 10 −3 S/cm for conventionally sintered ceramic specimens.…”
Section: Introductionmentioning
confidence: 99%
“…Powders with different characteristics are produced through different synthesis methods thus their sintering temperature is also different as listed in Table . This is due to different particle size, morphology and composition produced from different methods, evidencing a profound influence of synthesis methods on the processing temperature of ceramics …”
The ionic conductivity of solid electrolytes is dependent on synthesis and processing conditions, ie, powder properties, shaping parameters, sintering time (ts), and sintering temperature (Ts). In this study, Na3Zr2(SiO4)2(PO4) was sintered at 1200 and 1250°C for 0‐10 hours and its microstructure and electrical performance were investigated by means of scanning electron microscopy and impedance spectroscopy. After sintering under all conditions, the sodium super‐ionic conductor‐type structure was formed along with ZrO2 as a secondary phase. The microstructure investigation revealed a bimodal particle size distribution and grain growth at both Ts. The density of samples increased from 60% at 1200°C for 0 hours to 93% at 1250°C for 10 hours. The ionic conductivity of the samples increased with ts due to densification and grain growth, ranging from 0.13 to 0.71 mS/cm, respectively. The corresponding equivalent circuit fitting for the impedance spectra revealed that grain boundary resistance is the prime factor contributing to the changing conductivity after sintering. The activation energy of the bulk conductivity (Ea,bulk) remained almost constant (0.26 eV) whereas the activation energy of the total conductivity (Ea) exhibited a decreasing trend from 0.37 to 0.30 eV for the samples with ts = 0 and 10 hours, respectively—both sintered at 1250°C. In this study, the control of the grain boundaries improved the electrical conductivity by a factor of 6.
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