Next-generation Li1.3+xAl0.3AsxTi1.7-x(PO4)3 NASICON electrolytes with outstanding ionic conductivity performance

Abstract

NASICON-type solid electrolytes feature prominently in the improved safety and energy density of solid-state lithium batteries (ASSLBs). Achieving high ionic conductivity in these electrolytes is key to optimizing their performance. In this study, we introduced a new class of NASICON-type materials by doping arsenic into the Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 framework, creating a series of Li 1.3+x Al 0.3 As x Ti 1.7-x (PO 4 ) 3 phases with varying arsenic content (x = 0, 0.1, 0.2, 0.3), synthesized using the standard solid-state reaction method. X-ray diffraction confirmed the successful formation of the Li 1.3+x Al 0.3 As x Ti 1.7-x (PO 4 ) 3 phases, which was further validated by Rietveld refinement . Structural analyses through FT-IR, Raman spectroscopy , NMR , and ICP-AES studies validate the effective incorporation of arsenic into the lattice. Among the different compositions , Li 1.5 As 0.2 Al 0.3 Ti 1.5 (PO 4 ) 3 phase stood out due to its high relative density of 89 % and its pore-free microstructure, as observed through scanning electron microscopy results, revealing the largest grain and crystallite size. Notably, doping with arsenic resulted in a significant enhancement in ionic conductivity , increasing from 5.34 × 10 −5 Ω −1 cm −1 for Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 to 8.57 × 10 −4 Ω −1 cm −1 for the Li 1.5 As 0.2 Al 0.3 Ti 1.5 (PO 4 ) 3 at 25 °C. With a lithium transference number of 0.99, and a conduction mechanism largely unaffected by changes in temperature or composition, demonstrating its suitability as a promising candidate for solid electrolyte applications. • Arsenic-doped NASICON phases synthesized via solid-state reaction. • Li 1.5 As 0.2 Al 0.3 Ti 1.5 (PO 4 ) 3 showed 89 % relative density and pore-free microstructure. • Ionic conductivity reached 8.57 × 10 −4 Ω −1 cm −1 at 25 °C for x = 0.2. • Lithium transference number of 0.99 ensures excellent ionic mobility.