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 ( $$\sigma_{\text{Li}^{+}}$$ ) 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 Li6.58P2.76N0.03S10.12F0.05 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 Li6.58P2.76N0.03S10.12F0.05-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, LiNi0.8Co0.15Al0.05O2 (NCA)/Li6.58P2.76N0.03S10.12F0.05-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.