Elucidation of the structure of a new sodium superionic conductor, Na11Sn2PS12via single crystal XRD and AIMD simulations reveal isotropic 3D Na+-ion conduction pathways.

Experimental details, refinement data, Arrhenius plot, the Nyquist impedance plot and bond lengths (PDF) Data for Na 11.08 S 12 SbSn 2 (CIF) Data for Na 11.10 PS 12 Sn 2 (CIF)

The processing of garnet-type solid-state electrolytes remains challenging as densification conventionally requires high sintering temperatures and long processing times, which can result in severe Li loss, the formation of secondary phases, and thus high porosity and low ionic conductivity. Here, we report an ultrafast sintering method based on CO2 laser scanning with the assistance of a heating stage. We demonstrate the rapid densification of low-packing-density Li6.4La3Zr1.4Ta0.6O12 (LLZTO) films, which are difficult to densify by conventional furnace sintering methods. This unique approach has three fingerprint characteristics: (1) mitigation of Li loss through ultrafast sintering (dwelling time ≪1 s); (2) a unique anisotropic shrinkage behavior that greatly reduces film thickness; (3) wave-like surface topology from point scanning strategy that enables 3D interfacial contacts with electrode materials. Herein, highly dense (95.68%) and highly conductive (0.26 mS·cm–1 at 25 °C) LLZTO films are obtained through CO2 laser sintering. This work provides a unique, scalable, and widely applicable ultrarapid laser sintering technique to overcome the difficulties associated with classic methods for the integration of SSEs for practical all-solid-state Li-metal battery applications.

The search for new solid electrolyte materials and an understanding of fast-ion conductivity are crucial for the development of safe and high-power all-solid-state battery technology. Herein, we present the synthesis, structure, and properties of a crystalline lithium-ion conductor, Li 3.3 Al 0.15 P 0.85 S 4 (i.e., Li 9.9 Al 0.45 P 2.55 S 12 ), found in the compositional range Li 3+2x P 1−x Al x S 4 (x = 0.15, 0.20, and 0.33). 31 P magic-angle spinning nuclear magnetic resonance (MAS-NMR) aided in identifying the successful introduction of Al into the lattice. At high values of x (>0.15), crystalline Li 5 AlS 4 and a glassy amorphous component exsolve to yield a multiphase mixture. The crystal structure of Li 3.3 Al 0.15 P 0.85 S 4 was elucidated by single-crystal X-ray diffraction and powder neutron diffraction, demonstrating that it belongs to the thio-LISICON family with the Pnma space group, a = 12.9572(13) Å, b = 8.0861(8) Å, c = 6.1466(6) Å, and V = 644.00(11) Å 3 . The Li + -ion conductivity and diffusivity in this bulk material (which contains about 10 wt % of an amorphous phase, as prepared) were studied by electrochemical impedance spectroscopy and 7 Li pulsed-field gradient nuclear magnetic resonance spectroscopy (PFG-NMR). The total ionic conductivity of Li 3.3 Al 0.15 P 0.85 S 4 is 0.22(2) mS•cm −1 at room temperature with an activation energy of 0.30(1) eV. A two-component analysis method based on the Karger equations was developed to analyze the diffusive exchange between the bulk and amorphous phases of Li 3.3 Al 0.15 P 0.85 S 4 detected via the PFG-NMR signal attenuation curves. This approach was employed to quantitatively compare different sample morphologies (glass powder, crystalline powder, and crystalline pellets of Li 3.3 Al 0.15 P 0.85 S 4 ) and assess the influence of the macroscopic state on microscopic ion transport, as supported by NMR relaxation measurements.

We report a new ion conductor—Na11Sn2SbSe12—as a possible candidate for a solid catholyte in composite cathodes for all-solid state Na-batteries, which exhibits a room temperature ionic conductivity of 0.15 ± 0.03 mS cm−1 and an activation energy of 0.39 ± 0.02 eV. The sulfide solid solutions of Na11Sn2SbSe12, namely, Na11Sn2SbS12−xSex (x = 1 and 6), were also investigated through a combination of Rietveld refinement against powder x-ray diffraction data and electrochemical impedance spectroscopy to reveal the complex structure–property relationships governing ion transport in this class of materials. Meanwhile, broadening of the Na-ion diffusion pathways in Na11Sn2SbSe12 is expected to facilitate Na-ion transport compared to the sulfide-rich member of the solid solution, the opposite holds: increasing the Se fraction in Na11Sn2SbS12−xSex leads to a little change in the activation energy but a reduction in the ionic conductivity. We ascribe this to the lowering of the prefactor, σ 0, in the Arrhenius relationship with increasing lattice “softening” as a function of higher Se content.

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Garnet-type solid-state electrolytes have significant advantages over liquid organic electrolytes but require energy-intensive sintering to achieve high density and ionic conductivity. The aim of this study is to understand the...