Enhanced Ion Conduction via a Diverse Cl-PS₄ Anion Lattice in Li₃PS₄–xLiCl

Thiophosphates show promise as solid electrolytes for all-solid-state batteries (ASSBs), particularly Li 3 PS 4 -based materials, due to their cost-effectiveness and stability. To enhance conductivity for high-power applications, we developed affordable Li 3 PS 4 -LiCl (LPSCls) solid electrolytes with an ionic conductivity of ∼1.1 mS/cm (Li 3 PS 4:LiCl = 2:1, 200 °C). Our study examines the long- and short-range structural order and ion dynamics of LPSCls, using neutron diffraction, magic-angle-spinning nuclear magnetic resonance (MAS NMR), and electrochemical impedance spectroscopy (EIS). 31 P NMR reveals a unique disordered anion structure comprising a blend of Cl-modified β, γ, and amorphous PS 4 3– units. Additionally, NMR relaxometry highlights enhanced Li + mobility enabled by this diverse anion sublattice, allowing Li + ions to migrate efficiently among different anions with similar affinity. Our findings unveil novel anion species within LPSCls, offering insights for optimizing ionic conductivity in solid electrolytes for ASSBs.