Thin laminar composite solid electrolyte with high ionic conductivity and mechanical strength towards advanced all-solid-state lithium-sulfur battery

The development of thin solid-state electrolyte with high ionic conductivity and mechanical strength is of great importance for the high-performance all-solid-state lithium-sulfur battery. However, the state-of-the-art solid polymer electrolyte suffers from poor ionic conductivity and a high thickness but inferior mechanical strength. Herein, a thin laminar composite solid electrolyte (LCSE), namely Vr/PEO-LCSE, is fabricated by filtrating vermiculite nanosheets, followed by intercalation of PEO-LiTFSI into the interlayer through a swelling and filtration method. The continuous interlayer channels with improved PEO chain motility and LiTFSI dissociation afford Vr/PEO-LCSE a highly enhanced ionic conductivity of 1.22 x 10(-5) S cm(-1) at 25 degrees C. Together with the low thickness (10 mu m), Vr/PEO-LCSE achieves an ultralow area-specific resistance of 66 Omega cm(2) at 30 degrees C, about 50 times lower than pure PEO. Meanwhile, the typical brick-and-mortar architecture combined with the strong rigidity of vermiculite nanosheet imparts Vr/PEO-LCSE an excellent compressive strength of 131 MPa, 550% higher than that of pure PEO. As a result, the rate performance of the assembled Li-S battery is significantly improved. The Li vertical bar Vr/PEO-LCSE vertical bar S cell achieves low capacity fading as current density increases from 0.05C to 0.20C, and the discharge capacity recovers to 1100 mA h g(-1) when the current density switches back to 0.05C.