Dual-doping for enhancing chemical stability of functional anionic units in sulfide for high-performance all-solid-state lithium batteries

The sulfide-based solid-state electrolytes (SEs) reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufacturing and applications in all-solid-state lithium batteries (ASSLBs). Herein, we proposed an Al and O dual-doped strategy for Li₃PS₄ SE to regulate the chemical/electrochemical stability of anionic PS₄³⁻ tetrahedra to mitigate structural hydrolysis and parasitic reactions at the SE/Li interface. The optimized Li_3.08Al_0.04P_0.96S_3.92O_0.08 SE presents the highest σ_Li+ of 3.27 mS cm⁻¹, which is ∼6.8 times higher than the pristine Li₃PS₄ and excellently inhibits the structural hydrolysis for ∼25 min @ 25% humidity at RT. DFT calculations confirmed that the enhanced chemical stability was revealed to the intrinsically stable entities, e.g., POS₃³⁻ units. Moreover, Li_3.08Al_0.04P_0.96S_3.92O_0.08 SE cycled stably in Li//Li symmetric cell over 1000 h @ 0.1 mA cm⁻²/0.1 mA h cm⁻², could be revealed to Li-Al alloy and Li₂O at SE/Li interface impeding the growth of Li-dendrites during cycling. Resultantly, LNO@LCO/Li_3.08Al_0.04P_0.96S_3.92O_0.08/Li-In cell delivered initial discharge capacities of 129.8 mA h g⁻¹ and 83.74% capacity retention over 300 cycles @ 0.2 C at RT. Moreover, the Li_3.08Al_0.04P_0.96S_3.92O_0.08 SE presented >90% capacity retention over 200 and 300 cycles when the cell was tested with LiNi_0.8Co_0.15Al_0.05O₂ (NCA) cathode material vs. 5 and 10 mg cm⁻² @ RT.