Hybrid Lithium-Sulfur Batteries with an Advanced Gel Cathode and Stabilized Lithium-Metal Anode

The insulating nature of sulfur, polysulfide shuttle effect, and lithium-metal deterioration cause a decrease in practical energy density and fast capacity fade in lithium-sulfur (Li-S) batteries. This study presents an integrated strategy for the development of hybrid Li-S batteries based on a gel sulfur cathode, a solid electrolyte, and a protective anolyte composed of a highly concentrated salt electrolyte containing mixed additives. The dense solid electrolyte completely blocks polysulfide diffusion, and also makes it possible to investigate the cathode and anode independently. This gel cathode effectively traps the polysulfide active material while maintaining a low electrolyte to sulfur ratio of 5.2 mL g(-1). The anolyte effectively protects the Li metal and suppresses the consumption of liquid electrolyte, enabling stable long-term cycling for over 700 h in Li symmetric cells. This advanced design can simultaneously suppress the polysulfide shuttle, protect Li metal, and reduce the liquid electrolyte usage. The assembled hybrid batteries exhibit remarkably stable cycling performance over 300 cycles with high capacity. Finally, surface-sensitive techniques are carried out to directly visualize and probe the interphase formed on the surface of the Li1.5Al0.5Ge1.5(PO4)(3) (LAGP) pellet, which may help stabilize the solid-liquid interface.