Spodumene nanosheets@ZrO2-SiO2 heterostructure nanofibers modified separator for long-cycle lithium-sulfur batteries

Abstract

Lithium-sulfur batteries have become highly promising next-generation energy storage devices owing to their high theoretical capacity density, environmental friendliness, high cost-effectiveness, etc. Nevertheless, the commercial applications of Li-S batteries are severely hampered by the fatal shuttle effect of soluble lithium polysulfides (LiPSs) and sluggish reaction kinetics. To address these issues, a unique modifying interlayer of ZrO2-SiO2 heterostructure nanofibers inlaid with spodumene nanosheets (Spodumene@ZrO2-SiO2) has been innovatively designed and facilely prepared. In the interlayer, ZrO2-SiO2 heterostructure nanofibers provide abundant catalytic active sites to promote the conversion of LiPSs to improve kinetics, and effectively anchor LiPSs to reduce the shuttle effect. Simultaneously, the natural spodumene nanosheets as Li+ sieves offer selective Li+ transfer channels to allow Li+ fast transportation, but physically hinder the transportation of LiPSs owing to their small-size channels, further suppressing the shuttle effect of LiPSs. As a result, only host-free sulfur cathode by using this interlayer modified separator exhibits an extremely low capacity loss rate of 0.077 % per cycle during 500 cycles under 1 C. Even at the 2 C current density, the cathode still maintains a discharge-specific capacity of 630 mAh g−1, demonstrating the effectiveness of this strategy. With the help of combination of DFT and BVS theoretical calculations with the sound experiments, it is proved that the synergistic effects among physically and chemically anchoring LiPSs and catalytic capacity for LiPSs conversion of ZrO2-SiO2 heterostructure nanofibers, the Li+ selective transport and blocking effect for LiPSs shuttling of the spodumene nanosheets jointly achieve excellent long-life stability of Li-S battery. This study provides valuable insight into the design and fabrication of innovative separators for highly stable Li-S batteries via a cost-effective and environmentally friendly approach.