Electrolyte design for Li-conductive solid-electrolyte interphase enabling benchmark performance for all-solid-state lithium-metal batteries

Sulfide-based solid-state electrolytes (SSEs) with high Li⁺ conductivity (σ_Li+) and trifling grain boundaries have great potential for all-solid-state lithium-metal batteries (ASSLMBs). Nonetheless, the in-situ development of mixed ionic-electronic conducting solid-electrolyte interphase (SEI) at sulfide electrolyte/Li-metal anode interface induces uneven Li electrodeposition, which causes Li-dendrites and void formation, significantly severely deteriorating ASSLMBs. Herein, we propose a dual anionic, e.g., F and N, doping strategy to Li₇P₃S₁₁, tuning its composition in conjunction with the chemistry of SEI. Therefore, novel Li_6.58P_2.76N_0.03S_10.12F_0.05 glass-ceramic electrolyte (Li₇P₃S₁₁-5LiF-3Li₃N-gce) achieved superior ionic (4.33 mS·cm⁻¹) and lowest electronic conductivity of 4.33 × 10⁻¹⁰ S·cm⁻¹ and thus, offered superior critical current density of 0.90 mA·cm⁻² (2.5 times > Li₇P₃S₁₁) at room temperature (RT). Notably, Li//Li cell with Li_6.58P_2.76N_0.03S_10.12F_0.05-gce cycled stably over 1000 and 600 h at 0.2 and 0.3 mA·cm⁻² credited to robust and highly conductive SEI (in-situ) enriched with LiF and Li₃N species. Li₃N’s wettability renders SEI to be highly Li⁺ conductive, ensures an intimate interfacial contact, blocks reductive reactions, prevents Li-dendrites and facilitates fast Li⁺ kinetics. Consequently, LiNi_0.8Co_0.15Al_0.05O₂ (NCA)/Li_6.58P_2.76N_0.03S_10.12F_0.05-gce/Li cell exhibited an outstanding first reversible capacity of 200.8/240.1 mAh·g⁻¹ with 83.67% Coulombic efficiency, retained 85.11% of its original reversible capacity at 0.3 mA·cm⁻² over 165 cycles at RT.