Hierarchically porous carbon materials derived from MIL-88(Fe) for superior high-rate and long cycling-life sodium ions batteries

Nowadays, exploring a high performance, low cost, long cycling stability and superior excellent rate performance electrode materials for sodium-ion batteries (SIBs) remains big challenge. In this work, hierarchically porous carbon nanosheets (PCNs) are prepared by annealing Fe-based metal-organic frameworks (MOFs) material institute lavoisier-88 (MIL-88(Fe)) as precursors and then etching Fe-based composites via 2 M HCl. From the characterization analysis, PCNs exhibits a unique hollow and hierarchically porous structures with ultrafine carbon nanosheets, which could offer the high specific surface area, more electrochemical reaction active sites and fast charge transfer ability for sodium storage. When used as anode materials for SIBs, it shows high specific capacity of 215 mAh g−1 at 0.05 A g−1, and superior high rate performance with a capacity of 138 mAh g−1 at a very high current density of 2.5 A g−1 and superior long-cycling life due to its hierarchically porous property, high electrical conductivity, structural stability and enhanced pseudo-capacitive contribution from surface effects. The current strategy is promising to synthesize the porous carbon materials from MOFs for next generation energy storage application.