Flexible electrolyte-cathode bilayer framework with stabilized interface for room-temperature all-solid-state lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are promising next-generation energy storage system beyond state-of-the-art lithium-ion batteries because of their low cost and high energy density. However, liquid electrolyte-based LSBs suffer from polysulfide shuttle, and safety concerns originated from the use of flammable organic electrolytes and the formation of lithium dendrites. Herein, we report a novel bilayer framework through integrating a three-dimensional (3D) carbon nanofiber/sulfur (CNF/S) cathode with one-dimensional (1D) ceramic Li0.33La0.557TiO3 (LLTO) nanofiber-poly(ethylene oxide) (PEO) solid composite electrolyte to serve as both cathode and electrolyte for room-temperature ASSLSBs. The stabilized cycling performance of this novel bilayer structure design lies in the reduced interfacial resistance and enhanced electrode/electrolyte interfacial stability due to the addition of Li+ conducting 1D LLTO nanofibers, as well as the formed fast-continuous electron/ion transportation pathways within the 3D cathode architecture. Meanwhile, the mechanically robust bilayer framework with micro-/meso-pores could also accommodate the large volume change of sulfur during continuous charge-discharge process and help suppress the Li dendrite formation. As a result of the aforementioned benefits of the novel bilayer structure design, the introduced ASSLSBs could deliver a stable cycling performance at room temperature with high Coulombic efficiency of over 99%.