Résumé
The development of stable and high-performance solid electrolytes is critical for the commercialization of solid-state batteries (SSBs). This study explores materials with the composition Li9.6P3S12-kOk (0 ≤ k ≤ 1.0) by partially substituting sulfur with oxygen in Li9.6P3S12 to enhance electrochemical and ambient stability while maintaining high ionic conductivity. The synthesized compounds Li9.6P3S11.1O0.9 Li9.6P3S10.5O1.5, and Li9.6P3S9.9O2.1 having 7.5%, 12.5% and 17.5% oxygen content, named as LPSO-7.5, LPSO-12.5, and LPSO-17.5, exhibit an LGPStype structure with reduced secondary phases compared to previous studies. The highest ionic conductivity of 0.75 mS cm -1 was observed for LPSO-7.5 at 510 MPa, while increased oxygen content led to lower conductivity due to structural distortions and reduced lithium-ion mobility.
Electrochemical impedance spectroscopy (EIS) and symmetric Li/SE/Li cells confirmed improved electrochemical performance with lithium metal for LPSO-7.5. Full-cell tests with LiNi0.8Co0.15Al0.05O2 (NCA) cathode and graphite or lithium anodes showed that LPSO-7.5 demonstrated the highest capacity retention and the lowest polarization. Additionally, H2S gas evolution tests confirmed improved air stability with increasing oxygen content. The results indicate that moderate oxygen substitution optimally balances conductivity, air stability and interfacial compatibility. LPSO-7.5 emerges as a promising solid electrolyte candidate for nextgeneration SSBs with enhanced cycle life and reduced degradation.