Direct trapping and rapid conversing of polysulfides via a multifunctional Nb2O5-CNT catalytic layer for high performance lithium-sulfur batteries

Practical application of high-energy-density lithium-sulfur (Li–S) battery is greatly impeded by the detrimental shuttling effect and sluggish redox kinetics of polysulfides. Herein, a multifunctional Nb2O5-carbon nanotube (CNT) catalytic interface is designed and fabricated onto the separator, which can directly trap the polysulfides and then rapidly catalyze their redox conversion for advanced Li–S batteries. The construction of conductive and catalytic Nb2O5-CNT interface could afford long-distance electron transfer network, strong chemisorptive properties, and rich catalytic sites for accelerating polysulfide conversion kinetics and regulating Li2S nucleation/dissolution. The sulfur cathode with the assistant of Nb2O5-CNT interface could deliver an initial discharge capacity of 1286 mAh g−1 and remain 992 mAh g−1 with a capacity retention of 77.0%, corresponding to a low capacity attenuation rate of 0.23% per cycle during 100 cycles at 0.2C. Meanwhile, the Nb2O5-CNT interface can greatly suppress the self-discharge and effectively reduce the formation of lithium dendrite due to the inhibition of the shuttling effect. This work provides instructive insights to suppress the shuttle effect and accelerate redox conversion via designing a multifunctional catalytic interface for Li–S chemistry.