High-performance all-solid-state lithium batteries enabled by high-conductivity free-standing sulfide electrolyte membrane and Li-Zn/LiCl bifunctional interphase

All-solid-state lithium batteries (ASSLBs) empolying sulfide solid electrolyte and lithium metal anode can afford improved energy density and safety. However, their large-scale application is hampered by the rigidity of ceramic–based electrolyte and the inevitable growth of lithium dendrites. Herein, a novel, flexible, high-conductivity and free-standing sulfide electrolyte membrane (Li6PS5Cl-polypropylene carbonate6, (LPSCl-PPC6)) with a thickness of 60 μm is prepared via methodology of blade coating and hot pressing, which exhibits a high Li+ conductivity (3.1 × 10−3 S cm−1 at 25 °C) and a wide electrochemical window (4.7 V vs Li+/Li) at 25 °C. Additionally, a bifunctional interphase with Li-Zn/LiCl is implanted on lithium metal surface to enhance the stability of electrolyte/lithium anode, which effectively prevents the growth of lithium dendrites and the internal short circuit of lithium symmetric battery. Benefiting from the synergistic effect, the assembled ASSLBs of S-CNTs/LPSCl-PPC6/Li-Zn/LiCl|Li and LLZO@NCM93/LPSCl-PPC6/Li-Zn/LiCl|Li exhibit high initial capacity of 1183.5 mAh g−1 (193.6 mAh g−1) and exceptionally cyclic stability with capacity retention of 89.2% over 150 cycles at 0.05C (93.2% over 100 cycles at 0.1C). This highly conductive sulfide-based composite electrolyte and interface engineering provides a promising strategy for achieving high performance ASSLBs.