Oxygen-induced lithium inter-cage conduction for enhanced performance in all-solid-state batteries

Sulfide-based all-solid-state batteries suffer from interfacial degradation between the cathode and solid electrolyte, making it essential to maintain high ionic conductivity under such conditions. This study presents oxygen incorporation into solid electrolytes using Li₂SO₄ to enhance interfacial stability while minimizing conductivity loss. Oxygen was selectively substituted at Wyckoff 16 e sites in the PS₄ unit, inducing lithium redistribution and activating cage-to-cage conduction pathways, which mitigated conductivity degradation. Structural rearrangement and crystallinity were confirmed by neutron diffraction, MAS-NMR, XAS, and cryo-TEM. Despite the low polarizability of oxygen, lithium mobility was maintained due to reduced inter-cage Li–Li distances. The oxygen-doped electrolyte delivered 230 mAh g⁻¹ capacity, stable performance at a 50 C rate (9000 mA g⁻¹), 75% retention over 1000 cycles, and robust cycling over 500 cycles in a 400 Wh L⁻¹ pouch cell. This approach offers a scalable pathway for developing solid electrolytes that support high-performance all-solid-state batteries.