Hybrid co-based MOF nanoboxes/CNFs interlayer as microreactors for polysulfides-trapping in lithium-sulfur batteries

Lithium-sulfur battery is desirable for the future potential electrochemical energy storage device with advantages of high theoretical energy density, low cost and environmental friendliness. However, some natural hindrances, particularly fast capacity degradation resulting from the migration of dissolved polysulfide intermediates, remain to be significant challenges prior to the practical applications. In this work, a composite interlayer of carbon nanofibers (CNFs) which are enriched by Co-based metal organic frameworks (ZIF-67) growth in-situ is exploited. Notably, physical blocking and chemical trapping abilities are obtained synergistically from the ZIF/CNFs interlayer, which enables to restrain the dissolution of polysulfides and alleviate shuttle effect. Moreover, the three-dimensional fiber networks provide an interconnected conductive framework between each ZIF microreactor to promote fast electron transfer during cycling, thus contributing to excellent rate and cycling performance. As a result, Li-S cells with ZIF/CNFs interlayer show a high specific capacity of 1334 mAh g−1 at 1 C with an excellent cycling stability over 300 cycles. Besides, this scalable and affordable electrospinning fabrication method provides a promising approach for the design of MOFs-derived carbon materials for high performance Li-S batteries.