The impact of the particle size of a metal-organic framework for sulfur storage in Li-S batteries

The particle size of an electrode material is known to play an essential role in its electrochemical performance in Li-ion batteries. In Li-S batteries, porous host materials are applied to store sulfur and suppress the escape of polysulfides; yet the particle size of the host as an important parameter remains largely unexplored. Herein we chose ZIF-8, a metal-organic framework (MOF) proved promising for sulfur storage, as the proof-of-concept prototype, and systematically synthesized five sets of ZIF-8 samples of different particle sizes (from <20 nm to >1 μm), using them as S@MOF cathodes. The results show that sulfur utilization increases monotonically with the decrease of ZIF-8 particle size (<20 nm: >950 mA h g^-1 at 0.5 C), while the best cycling stability (75% over 250 cycles at 0.5 C) is achieved with a moderate size (∼200 nm).