Metal-nitrogen-doped hybrid ionic/electronic conduction triple-phase interfaces for high-performance all-solid-state lithium-sulfur batteries

The point-to-point contact mechanism in all-solid-state Li-S batteries (ASSLSBs) is not as efficient as a liquid electrolyte which has superior mobility in the electrode, resulting in a slower reaction kinetics and inadequate ionic/electronic conduction network between the S (or Li₂S), conductive carbon, and solid-state electrolytes (SSEs) for achieving a swift (dis)charge reaction. Herein, a series of hybrid ionic/electronic conduction triple-phase interfaces with transition metal and nitrogen co-doping were designed. The graphitic ordered mesoporous carbon frameworks (TM-N-OMCs; TM = Fe, Co, Ni, and Cu) serve as hosts for Li₂S and Li₆PS₅Cl (LPSC) and provide abundant reaction sites on the triple interface. Results from both experimental and computational research display that the combination of Cu-N co-dopants can promote the Li-ion diffusion for rapid transformation of Li₂S with adequate ionic (6.73 × 10⁻⁴ S·cm⁻¹)/electronic conductivities (1.77 × 10⁻² S·cm⁻¹) at 25 °C. The as-acquired Li₂S/Cu-N-OMC/LPSC electrode exhibits a high reversible capacity (1147.7 mAh·g⁻¹) at 0.1 C, excellent capacity retention (99.5%) after 500 cycles at 0.5 C, and high areal capacity (7.08 mAh·cm⁻²).