Facile synthesis of MOFs derived Fe7S8/C composites for high capacity and long-life rechargeable lithium/sodium batteries

Abstract

Abstract Searching for low-cost, high capacity, stable and well-designed cathode materials with good rate capability and long-life cycling performances is our long-term goal for rechargeable lithium/sodium batteries. In this work, a simple and scalable strategy is developed to synthesize metal-organic frameworks (MOFs) derived Fe7S8/C composites by sulfurizing Fe-MIL-88A MOFs. The synthesized Fe7S8/C composites are of rod-like morphology with the well-dispersed Fe7S8 nanoparticles in porous carbon matrix. Such a structure could offer distinct advantages for Fe7S8-based electrode materials for both lithium and sodium batteries. When evaluated as a cathode material for rechargeable Fe7S8/Li batteries, the Fe7S8/C composites exhibit a long and flat discharge plateau around 1.5 V and delivers a high specific discharge capacity of 473 mA h g−1 at 0.1 A g−1 after 100 cycles with excellent rate capability and long-life cycling performance at high current density (~301 mA h g−1after 1000 cycles at 1.0 A g−1). Moreover, the Fe7S8/C composites could also exhibit high specific capacities, good rate performance and high cycling stability as an anode material for sodium ion batteries. Our findings demonstrate that Fe7S8/C composites with rod-like morphology are promising electrode materials for lithium/sodium batteries.