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.
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