A (110) Facet-Dominated Vanadium Dioxide Enabling Bidirectional Electrocatalysis for Lithium-Sulfur Batteries

Catalysis is an effective way to improve the performance of lithium-sulfur (Li-S) batteries by enhancing the reaction kinetics of polysulfides. However, the bidirectional catalysis for discharging and charging processes in Li-S battery is still challenging. Herein, a (110) facet-dominated VO2 is prepared through the thermal-induced partial decomposition of (NH4)2V4O9 (NVO), forming a (110)VO2@NVO hybrid with the bidirectional catalysis ability. This (110) facet-dominated VO2 shows the ability to break the S-S bond to guide the Li2S deposition in the reduction process and reduce the delithiation barrier of Li2S to promote the oxidation process. The above hybrid is loaded on carbon nanofiber (CNF) to build an interlayer, where the 3D CNF and the conductive NVO ensure the fast electron transfer. The assembled battery with the above interlayer exhibits a high capacity of 1038 mAh g-1 after 300 cycles at 0.1 C (capacity retention: 70%). At a high rate of 5 C, a high capacity of 521 mAh g-1 after 1000 cycles is reached. Even under an ultrahigh sulfur loading of 10.3 mg cm-2 and a low electrolyte/sulfur ratio of 4 μL mgS-1, stable cycling performance with a high capacity of >3 mAh cm-2 is also achieved.