Natural Cocoons Enabling Flexible and Stable Fabric Lithium–Sulfur Full Batteries

Highlights: A creative cooperative strategy involving silk fibroin/sericin is proposed for stabilizing high-performance flexible Li–S full batteries with a limited Li excess of 90% by simultaneously inhibiting lithium dendrites, adsorbing liquid polysulfides, and anchoring solid lithium sulfides.Such fabric Li–S full batteries offer high volumetric energy density (457.2 Wh L), high-capacity retention (99.8% per cycle), and remarkable bending capability (6000 flexing cycles at a small radius of 5 mm). Abstract: Lithium–sulfur batteries are highly appealing as high-energy power systems and hold great application prospects for flexible and wearable electronics. However, the easy formation of lithium dendrites, shuttle effect of dissolved polysulfides, random deposition of insulating lithium sulfides, and poor mechanical flexibility of both electrodes seriously restrict the utilization of lithium and stabilities of lithium and sulfur for practical applications. Herein, we present a cooperative strategy employing silk fibroin/sericin to stabilize flexible lithium–sulfur full batteries by simultaneously inhibiting lithium dendrites, adsorbing liquid polysulfides, and anchoring solid lithium sulfides. Benefiting from the abundant nitrogen- and oxygen-containing functional groups, the carbonized fibroin fabric serves as a lithiophilic fabric host for stabilizing the lithium anode, while the carbonized fibroin fabric and the extracted sericin are used as sulfiphilic hosts and adhesive binders, respectively, for stabilizing the sulfur cathode. Consequently, the assembled Li–S full battery provided a high areal capacity (5.6 mAh cm), limited lithium excess (90%), a high volumetric energy density (457.2 Wh L), high-capacity retention (99.8% per cycle), and remarkable bending capability (6000 flexing cycles at a small radius of 5 mm).[Figure not available: see fulltext.].