Relay catalyst for accelerating lithium polysulfide conversion kinetics and long-life lithium sulfur batteries

Lithium-sulfur (Li-S) batteries are regarded as promising candidates for next-generation secondary batteries due to their high energy density and cost-effectiveness. However, the sluggish conversion kinetics of lithium polysulfide (LiPSs) intermediates during charge/discharge cycles severely hinder their practical application. Herein, we propose a relay catalysts design strategy to accelerate the sulfur reduction conversion process in Li-S batteries. To validate this approach, we synthesized a faujasite-type molecular sieve (FAU)-Bi₂O₃ relay catalyst, in which each component is tailored to optimize distinct stages of the catalytic process. FAU, with its abundant microporous structure, effectively captures and channels LiPSs toward the Bi₂O₃ interface, where catalytic sites promote rapid conversion and enhance reaction kinetics. Furthermore, integrating the FAU-Bi₂O₃ catalyst onto a commercial separator not only boosts electrochemical performance but also imparts excellent flame retardancy. Li-S batteries with FAU-Bi₂O₃ achieve a high specific capacity of 846.8 mAh g⁻¹ after 100 cycles, while the pouch cell maintains a capacity retention of 81.4 % after 70 cycles. This work presents a rational catalyst design strategy, offering a new pathway for advancing Li-S battery technology toward practical implementation.